Co-reporter:Yi Zeng;Rui Wang;Wuyou Fu;Lijie Wang;Haibin Yang
The Journal of Physical Chemistry C March 5, 2009 Volume 113(Issue 9) pp:3442-3448
Publication Date(Web):2017-2-22
DOI:10.1021/jp8082166
The flowerlike ZnO nanorod bundles, consisting of closely packed nanorods with diameter of ∼90 nm, have been successfully synthesized by a poly(ethylene glycol) (PEG)-assisted hydrothermal route at low temperature (80 °C). The results characterized from FESEM, TEM, and SAED demonstrate that the nanorod structures are single crystals and formed from self-assembled nanoparticles. Further investigation of the formation mechanism reveals that the PEG-assisted hydrothermal process is vital to the formation of the complex nanostructures. The sensors based on the ZnO nanostructures exhibit excellent ethanol-sensing properties at reduced working temperature (250 °C), which could still respond to 1 ppm ethanol. The sensitivity of the sensor to 100 ppm ethanol is about 154.3 with the response time of 12 s. The enhancement in sensing properties of the present ZnO sensor may be attributed to the peculiar ZnO nanostructures.
Co-reporter:Ziying Wang, Chen Zhao, Tianyi Han, Yong Zhang, Sen Liu, Teng Fei, Geyu Lu, Tong Zhang
Sensors and Actuators B: Chemical 2017 Volume 242() pp:269-279
Publication Date(Web):April 2017
DOI:10.1016/j.snb.2016.10.101
•We have demonstrated a combined surface modification and heteroatom doping approach to enhance the sensing performances of RGO-based room-temperature NO2 sensors, where SnO2 nanoparticles modified nitrogen-doped RGO (SnO2/N-RGO) hybrids had been used as sensing materials.•The sensor based on SnO2/N-RGO hybrids exhibits better sensing performances toward NO2 operated at room temperature than those of pure RGO and SnO2/RGO hybrids.•The SnO2/N-RGO hybrids show response of 1.38–5 ppm NO2 with the response time and recovery time of 45 s and 168 s. The excellent sensing performances are attributed to incorporation of N atoms into RGO and the modification of RGO with SnO2 NPs.Reduced graphene oxide (RGO)-based NO2 sensors have attracted considerable attention due to their excellent advantages of low power consumption and manufacturability to facilitate massive deployment. However, it is still a great challenge to fabricate RGO-based room-temperatureNO2 sensors with excellent sensing performances. Herein, we have demonstrated a combined surface modification and heteroatom doping approach to enhance the sensing performances of RGO-based room-temperature NO2 sensors, where SnO2 nanoparticles modified nitrogen-doped RGO (SnO2/N-RGO) hybrids had been used as sensing materials. The SnO2/N-RGO hybrids were prepared by hydrothermal synthesis method using SnCl4, GO and urea as precursors. The combined characterizations of X-ray diffraction (XRD), energy-dispersive X-ray spectrometer (EDS), elemental mapping, X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), Raman spectra as well as N2 sorption isotherm were used to characterize the materials thus obtained, indicating the successful preparation of SnO2/N-RGO hybrids. During the hydrothermal progress, SnCl4 conversed into SnO2 nanoparticles (NPs), and GO was reduced into RGO, while urea was decomposed into nitrogen-containing molecule and doped into RGO. It is found that SnO2 NPs with the size of 3–5 nm are uniformly dispersed on N-RGO nanosheets. Most importantly, SnO2/N-RGO hybrids-based sensor exhibits superior sensing performances toward NO2 operated at room temperature, which are better than those of pure RGO and SnO2/RGO hybrids. For example, SnO2/N-RGO hybrids show response of 1.38 to 5 ppm NO2 with the response time and recovery time of 45 s and 168 s. The excellent sensing performances are attributed to incorporation of N atoms into RGO and the modification of RGO with SnO2 NPs. This novel sensor based on SnO2/N-RGO hybrids promises to provide an essential sensing platform for the detection of NO2 with excellent sensing performances at room temperature.
Co-reporter:Feng Li, Xing Gao, Rui Wang, Tong Zhang, Geyu Lu
Sensors and Actuators B: Chemical 2017 Volume 248(Volume 248) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.snb.2016.12.009
•The TiO2-SnO2 core-shell nanofibers were successfully synthesized by a coaxial electrospinning method.•The sensors exhibited excellent sensing properties including quick response to acetone, high response to acetone and good selectivity.•The mechanism relies on the changes of amount of adsorbed oxygen species and electron depletion layer on the surface.A core-shell heterostructure nanofibers (NFs) have been synthesized via a coaxial electrospinning approach. Two semiconducting metal oxides (SMOX) with different work function were selected to form the core-shell heterostructure NFs. In this work, SnO2 and TiO2 were chosen as the selected SMOXs for the synthesis of the core-shell heterostructure NFs. The electrons in TiO2 will flow to SnO2, because the work function of TiO2 is smaller than SnO2. This phenomenon could result in an increase of the electrons concentration in the SnO2 shell layers and the amount of adsorbed oxygen species increased. Therefore, the gas sensing properties of the TiO2-SnO2 core-shell heterostructure NFs were enhanced including a high response to the target gas, good selectivity to the target gas and the rapid response/recovery processes. The approach and results proposed in this study may contribute to the realization of more sensitive core-shell heterostructure NFs sensors.
Co-reporter:Lili Wang, Rui Zhang, Tingting Zhou, Zheng Lou, Jianan Deng, Tong Zhang
Sensors and Actuators B: Chemical 2017 Volume 239() pp:211-217
Publication Date(Web):February 2017
DOI:10.1016/j.snb.2016.08.013
P-type Cu2O nanostructures with an interesting morphological evolution (from cube, truncated octahedral to octahedral) were realized simply by adjusting the amounts of PVP used. Octahedral Cu2O particles exposing only the {111} facets exhibit a surprisingly competitive sensing activity to CO gases in relatively low working temperature due to high-energy surfaces, large percentage of surface copper atoms density and dangling bonds compared with cube Cu2O with (100) facets and truncated octahedral Cu2O with (100) and (111) facets. Our findings may provide an opportunity to explore a simple, efficient, cost-effective and promising sensing/catalysis activity materials in gas sensors, gas catalysis and photo-catalysis.Shape-dependent sensing properties of the Cu2O polyhedrons-based sensors are designed and the Cu2O with exposed {111} facets shows high CO sensing response and great potential for gas sensor.
Co-reporter:Lili Wang, Zheng Lou, Rui Zhang, Tingting Zhou, Jianan Deng, and Tong Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 10) pp:6539
Publication Date(Web):March 4, 2016
DOI:10.1021/acsami.6b00305
Novel hybrid Co3O4/SnO2 core–shell nanospheres have been effectively realized by a one-step hydrothermal, template-free preparation method. Our strategy involves a simple fabrication scheme that entails the coating of natural cross-link agents followed by electrostatic interaction between the positive charges of Sn and Co ions and the negative charge of glutamic acid. The core–shell architecture enables novel flexibility of gas sensor surfaces compared to commonly used bulk materials. The highly efficient charge transfer and unique structure are key to ensuring the availability of high response and rapid-response speed. It demonstrates how hybrid core–shell nanospheres can be used as an advance function material to fabricate electrical sensing devices that may be useful as gas sensors.Keywords: Co3O4/SnO2; core−shell nanospheres; fast response time; gas sensors; hybrid structure; porous structure
Co-reporter:Kai Jiang, Hongran Zhao, Jianxun Dai, Da Kuang, Teng Fei, and Tong Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 38) pp:25529
Publication Date(Web):September 6, 2016
DOI:10.1021/acsami.6b08071
A catalyst-free Friedel–Crafts alkylation reaction has been developed to synthesize hierarchically porous polymeric microspheres (HPPMs) with phloroglucin and dimethoxymethane. HPPMs with uniform size were obtained and the size can be tuned by the concentration of raw materials. The chemical structure and hierarchical porous characteristic of HPPMs were characterized in detail. HPPMs were then loaded with humidity sensitive material LiCl to construct composites for humidity sensor. The optimum sensor based on 3 wt % LiCl-loaded HPPMs shows high sensitivity at the relative humidity (RH) atmosphere of 11–95%, small hysteresis, enhanced durability and rapid response. The sensitive mechanism was discussed through the investigation of complex impedance plots.Keywords: cross-linked; Friedel−Crafts alkylation; hierarchically porous polymeric microspheres; humidity sensor; LiCl loaded
Co-reporter:Feng Li, Xing Gao, Rui Wang, Tong Zhang, Geyu Lu, and Nicolae Barsan
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 30) pp:19799-19806
Publication Date(Web):July 12, 2016
DOI:10.1021/acsami.6b04063
The metal oxide semiconductor (MOS) core–shell heterostructure nanofibers (NFs) have been successfully synthesized via an environmentally friendly coaxial electrospinning approach. To demonstrate the potential applications of the as-prepared samples, sensors based on MOS core–shell heterostructure NFs have been fabricated and their gas sensing properties were investigated. Results show that the sensors exhibit an advanced gas sensing property to trimethylamine (TMA) including the outstanding selectivity and rapid response/recovery processes in comparison with the sensors based on single MOS NFs. These phenomena are closely associated with the electron flow caused by the work function difference between MOS of the core and the shell. The approach proposed in this study may contribute to the realization of more sensitive MOS core–shell heterostructure sensors.
Co-reporter:Rui Zhang, Tingting Zhou, Lili Wang, Zheng Lou, Jianan Deng and Tong Zhang
New Journal of Chemistry 2016 vol. 40(Issue 8) pp:6796-6802
Publication Date(Web):01 Jun 2016
DOI:10.1039/C6NJ00365F
Core–shell SnO2@ZnO composite nanospheres were successfully prepared by using carbon spheres as sacrificial templates via a facile three-step procedure including a hydrothermal method. In contrast, pristine SnO2 nanospheres and ZnO nanoparticles were obtained through a similar method with different steps, respectively. The composition and structures of the as-synthesized samples were confirmed by a series of characterization procedures. The obtained composite materials exhibited the special core-in-hollow-shell structure at the nanometer level. And as potential sensing materials, the obtained core–shell SnO2@ZnO composite nanomaterials demonstrated better gas sensing properties to ethanol including higher response, better selectivity, faster response and favorable repeatability, which may be related to the special core-in-hollow-shell structure with a porous surface and the hetero-contact between two different metal oxide semiconductors.
Co-reporter:Yong Zhang, Ziying Wang, Sen Liu, Tong Zhang
Materials Research Bulletin 2016 Volume 84() pp:355-362
Publication Date(Web):December 2016
DOI:10.1016/j.materresbull.2016.08.031
•In situ growth of Ag-rGO-CNT has been performed by electrodeposition method.•The Ag-rGO-CNT/ITO electrode can be used for non-enzymatic detection of H2O2.•The sensor based on Ag-rGO-CNT/ITO shows linear detection range of 0.05–1.40 mM.•The detection limit of the sensor is estimated to be 1.32 μM.Herein, a two-step electrodepostion method was carried out for in situ growth of Ag metal-reduced graphene oxide-carbon nanotube on indium tin oxide (Ag-rGO-CNT/ITO). Firstly, rGO-CNT hybrids have been synthesized on ITO electrode by electrodeposition of GO-CNT dispersion, and then, Ag metal has been deposited on the surface of rGO-CNT/ITO by the electrodeposition method. Combining unique properties of rGO-CNT hybrids and excellent catalytic activity of Ag metal, Ag-rGO-CNT/ITO exhibits good catalytic activity for electrocatalytic reduction of hydrogen peroxide (H2O2). The non-enzymatic H2O2 sensor based on Ag-rGO-CNT/ITO electrode shows the linear detection range about 0.05–1.40 mM (R = 0.999), and the detection limit is estimated to be 1.32 μM at a signal-to-noise ratio of 3. Furthermore, the Ag-rGO-CNT/ITO electrode exhibits good anti-interference capability, compared to other interferences such as ascorbic acid, dopamine, uric acid, NaNO3, NaNO2 and glucose.
Co-reporter:Sen Liu, Ziying Wang, Yong Zhang, Jiacheng Li, Tong Zhang
Sensors and Actuators B: Chemical 2016 Volume 228() pp:134-143
Publication Date(Web):2 June 2016
DOI:10.1016/j.snb.2016.01.023
The development of graphene-based room temperature gas sensors has drawn massive attention due to their unique advantage of gas sensing at room temperature. In this paper, in pursuit of developing high-performance graphene-based gas sensors, a NO2 gas sensor has been successfully fabricated using sulfonated reduced graphene oxide (S-rGO) anchoring with SnO2 nanoparticles as sensing materials. The SnO2 nanoparticles modified S-rGO (SnO2/S-rGO) hybrids were prepared by deposition of SnO2 nanoparticles on the surface of S-rGO through hydrothermal synthesis method. The combined characterizations of X-ray diffraction, UV–vis spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, energy-dispersive spectroscopy, as well as N2 sorption isotherm indicate the successful preparation of SnO2/S-rGO hybrids with porous structure. Most importantly, SnO2/S-rGO hybrids exhibit good sensing performances for detection of NO2 at room temperature, such as high response, fast response and recovery rate, and good selectivity. The sensor based on SnO2/S-rGO hybrids exhibits better sensing performances than the previously reported rGO-based gas sensors. Furthermore, the excellent sensing performances of sensor based on SnO2/S-rGO also render it suitable for development of high performance gas sensors operated at room temperature.
Co-reporter:Lili Wang, Rui Zhang, Tingting Zhou, Zheng Lou, Jianan Deng, Tong Zhang
Sensors and Actuators B: Chemical 2016 Volume 223() pp:311-317
Publication Date(Web):February 2016
DOI:10.1016/j.snb.2015.09.114
We report a facile and efficient method for the synthesis of novel concave Cu2O octahedral nanostructure. The concave Cu2O octahedral nanostructure has an average diameter of 400 nm. Moreover, the Cu2O nanorods were also prepared by controlling the hydroxylamine hydrochloride (NH2OH·HCl) concentrations. The concave Cu2O octahedral nanostructures were evaluated as a sensing materials for benzene (C6H6) detection at operating temperature of 230 °C and the results reveal that it has excellent sensing dependence to C6H6 concentration changes. Interestingly, The concave Cu2O octahedral nanostructure also has good sensing response to NO2 at relatively low operating temperatures of 50 °C with high response of 4.3 and the response and recovery time shorter than 20 and 131 s to 20 ppm, respectively. The multifunctional concave Cu2O octahedral nanostructures would be promising functional nanomaterials in sensor fields.Concave Cu2O octahedral have been synthesized by a solution route and exhibited good selectivity at different working temperature.
Co-reporter:Kai Jiang, Hongran Zhao, Teng Fei, Huimin Dou, Tong Zhang
Sensors and Actuators B: Chemical 2016 Volume 222() pp:440-446
Publication Date(Web):January 2016
DOI:10.1016/j.snb.2015.08.004
A nanoporous organic polymer based on triphenylamine was synthesized, and the structure and morphology of the resultant polytriphenylamine (PTPA) were described by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption/desorption analysis. PTPA was acted as the host to load the guest Fe(NO3)3 for preparing humidity sensitive composites. Compared with pure PTPA sensor, Fe(NO3)3/PTPA sensors showed improved humidity sensitive properties, especially the 20 wt% Fe(NO3)3/PTPA sensor. The impedance of the 20 wt% Fe(NO3)3/PTPA sensor changed four orders of magnitude over the whole humidity range, with a good linearity, litter hysteresis, rapid response and good long-time stability. The complex impedance plots and direct current (DC) reverse polarity method were used to research the mechanism of the optimized sensor.
Co-reporter:Pengjia Qi;Ziying Wang;Rui Wang;Yinan Xu
Chemical Research in Chinese Universities 2016 Volume 32( Issue 6) pp:924-928
Publication Date(Web):2016 December
DOI:10.1007/s40242-016-6129-z
Synthetic graphene composite was modified on a transducer of quartz crystal microbalance(QCM) to fabricate a gas sensor for low concentration nitrogen dioxide(NO2) detection. The gas sensing properties of the QCM coated with SnO2-rGO and AgNPs-SnO2-rGO composites were investigated when exposing QCM to low NO2 con-centration(2.05—20.5 mg/m3) atmosphere at room temperature. The sensing performances of the QCM with AgNPs-SnO2-rGO composites were enhanced by the introduction of Ag nanoparticles, and the QCM modified with AgNPs-SnO2-rGO composites could detect NO2 at room temperature.
Co-reporter:Lili Wang, Tingting Zhou, Rui Zhang, Zheng Lou, Jianan Deng, Tong Zhang
Sensors and Actuators B: Chemical 2016 Volume 227() pp:448-455
Publication Date(Web):May 2016
DOI:10.1016/j.snb.2015.12.097
Nanosheet-assembled Zn2SnO4 hierarchical structure had been prepared by a hydrothermal method at 180 °C. Different structures such as hierarchical sphere and solid cube are obtained by using different surfactants. The sensor based on nanosheet-assembled Zn2SnO4 hierarchical structure materials outperforms many other hierarchical sphere and solid cube-like Zn2SnO4 materials in response to toluene detection. Close investigation revealed that the Zn2SnO4 nanosheet-based sensors exhibited fast response speed at 280 °C after 4 cycles as the sensing materials of gas sensor, indicating that the hierarchical compounds might have a promising future in the gas sensor application field.Hierarchical rod-like Zn2SnO4 structure (sheet) prepared by a hydrothermal method, exhibit a fast toluene response time as a novel sensing material for gas sensor.
Co-reporter:Teng Fei, Jianxun Dai, Kai Jiang, Hongran Zhao, Tong Zhang
Sensors and Actuators B: Chemical 2016 Volume 227() pp:649-654
Publication Date(Web):May 2016
DOI:10.1016/j.snb.2016.01.038
The stability of sensitive materials is of great importance to humidity sensors. A novel method is used to synthesize cross-linked polymers by a free radical polymerization while introducing the pyridine salt unit with a click reaction by a one-pot reaction. The obtained polymers were used for humidity sensors and the humidity sensitive properties were researched systematically. By introducing polar units to the side chain of the polymer, the humidity sensitive properties were improved greatly. The optimum sensor shows good sensing properties during the whole relative humidity range. In addition, the polymer sensor shows very quick response to humidity, with a response time of 6 s and a recovery time of 17 s. This method is also applicable for developing other functional materials.
Co-reporter:Jing Cao, Ziying Wang, Rui Wang, Sen Liu, Teng Fei, Lijie Wang and Tong Zhang
Journal of Materials Chemistry A 2015 vol. 3(Issue 10) pp:5635-5641
Publication Date(Web):27 Jan 2015
DOI:10.1039/C4TA06892K
Different components and well-defined structures may cooperatively improve the performances of composite materials and enhance their applicability. In this paper, core–shell α-Fe2O3@NiO nanofibers (α-Fe2O3@NiO CSNFs) with hollow nanostructures are synthesized by a facile coaxial electrospinning method and calcination procedure. Considering the temperature-dependent solute degradation process and different influencing factors including the solvent evaporation rate and phase separation, a multistage formation mechanism has been proposed to understand the formation of the CSNF structure. The gas sensing tests indicate that the α-Fe2O3@NiO CSNFs exhibit significantly improved gas sensitivity and selectivity performances in comparison with NiO hollow nanofibers (NiO HNFs) and α-Fe2O3 nanofibers (α-Fe2O3 NFs). The response of α-Fe2O3@NiO CSNFs to 50 ppm HCHO at 240 °C is ∼12.8, which is 10- and 7.1-times higher than those of pure NiO and α-Fe2O3, respectively. The synergy between the heterojunction, core–shell hollow nanofiber structure and Fe loading into the NiO shell contribute to the enhanced response of α-Fe2O3@NiO CSNFs. Moreover, extremely fast response–recovery behavior (∼2 s and ∼9 s) has been observed at the optimal working temperature of 240 °C. The detection limit for HCHO could be lower than 1 ppm. These favorable gas sensing performances make the α-Fe2O3@NiO CSNFs promising materials for gas sensors.
Co-reporter:LiLi Wang, Zheng Lou, Jianan Deng, Rui Zhang, and Tong Zhang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 23) pp:13098
Publication Date(Web):May 26, 2015
DOI:10.1021/acsami.5b03978
Three-dimensional (3D) nanostructures of α-Fe2O3 materials, including both hollow sphere-shaped and yolk-shell (core-shell)-shaped, have been successfully synthesized via an environmentally friendly hydrothermal approach. By expertly adjusting the reaction time, the solid, hollow, and yolk-shell shaped α-Fe2O3 can be selectively synthesized. Yolk-shell α-Fe2O3 nanospheres display outer diameters of 350 nm, and the interstitial hollow spaces layer is intimately sandwiched between the inner and outer shell of α-Fe2O3 nanostructures. The possible growth mechanism of the yolk-shell nanostructure is proposed. The results showed that the well-defined bilayer interface effectively enhanced the sensing performance of the α-Fe2O3 nanostructures (i.e., yolk-shell α-Fe2O3@α-Fe2O3), owing predominantly to the unique nanostructure, thus facilitated the transport rate and augmented the adsorption quantity of the target gas molecule under gas detection.Keywords: ethanol sensing; fast response time; gas sensor; porous structure; yolk-shell nanospheres; α-Fe2O3;
Co-reporter:Sen Liu, Ziying Wang, Yong Zhang, Zhuo Dong and Tong Zhang
RSC Advances 2015 vol. 5(Issue 111) pp:91760-91765
Publication Date(Web):19 Oct 2015
DOI:10.1039/C5RA18680C
In this paper, in pursuit of developing high-performance graphene-based gas sensors, a novel NO2 gas sensor has been successfully fabricated using ZnO nanoparticles and Au nanoparticles modified reduced graphene oxide (ZnO–rGO–Au) ternary hybrids as sensing materials. The ZnO–rGO–Au hybrids were prepared by deposition of Au nanoparticles on the surface of ZnO–rGO hybrids by the wet chemical method. The combined characterizations of X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, energy-dispersive spectroscopy, as well as N2 sorption isotherm indicate the successful preparation of ZnO–rGO–Au hybrids. Most importantly, ZnO–rGO–Au hybrids exhibit good sensing performances for detection of NO2 at relatively low operating temperature (80 °C), such as high response, fast response and recovery rate, and good selectivity. Furthermore, the excellent sensing performances of sensor based on ZnO–rGO–Au hybrids also render it suitable for development of high performance gas sensors.
Co-reporter:Yong Zhang, Ye Ji, Ziying Wang, Sen Liu and Tong Zhang
RSC Advances 2015 vol. 5(Issue 129) pp:106307-106314
Publication Date(Web):10 Dec 2015
DOI:10.1039/C5RA24727F
Reduced graphene oxide–carbon nanotube (rGO–CNT) hybrids have been synthesized by electrodeposition of GO stabilized CNT using indium tin oxide (ITO) as working electrode, followed by electrochemical reduction of GO–CNT into rGO–CNT on the surface of ITO. The combined characterizations of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses have been used to examine the structure of rGO–CNT hybrids, indicating the successful preparation of hybrids. More importantly, compared with the bare ITO and rGO/ITO electrodes, the rGO–CNT/ITO electrode exhibits excellent sensing performance for electrochemical detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA), leading to a high-performance electrochemical sensor for simultaneous detection of AA, DA and UA. The linear detection ranges of the AA, DA and UA sensors based on rGO–CNT hybrids were estimated to be 10–200 μM, 0.2–8.0 μM and 0.2–16.0 μM, and the detection limits were 5.31 μM, 0.04 μM and 0.17 μM, respectively.
Co-reporter:Yong Zhang, Ziying Wang, Ye Ji, Sen Liu and Tong Zhang
RSC Advances 2015 vol. 5(Issue 49) pp:39037-39041
Publication Date(Web):23 Apr 2015
DOI:10.1039/C5RA04246A
Ag nanoparticle–carbon nanotube–reduced graphene oxide (AgNPs–CNT–rGO) hybrids have been synthesized by reduction of GO in CNT–GO hybrids and AgNO3. The linear detection range and detection limit of the H2O2 sensor based on AgNPs–CNT–rGO hybrids were estimated to be from 0.01 mM to 10 mM (R = 0.997), and 1 μM, respectively.
Co-reporter:Sen Liu, Yong Zhang, Ziying Wang, Bo Yu, Shenguan Song and Tong Zhang
RSC Advances 2015 vol. 5(Issue 47) pp:37568-37573
Publication Date(Web):20 Apr 2015
DOI:10.1039/C5RA04961J
N-doped few-layer graphene-supported yolk–shell carbon hollow spheres (CHSs/N-G) have been prepared by confined nanospace pyrolysis of GO–polypyrrole (GO–PPy) hybrids obtained by self-assembly of GO and PPy particles. More importantly, such CHSs/N-G exhibits electrochemical catalytic activity for oxidation of L-cysteine, leading to a high performance L-cysteine sensor with detection limit and linear range of 0.2 μM and 2 μM to 80 μM, respectively.
Co-reporter:Jing Cao, Ziying Wang, Rui Wang, Sen Liu, Teng Fei, Lijie Wang and Tong Zhang
RSC Advances 2015 vol. 5(Issue 46) pp:36340-36346
Publication Date(Web):07 Apr 2015
DOI:10.1039/C5RA03675E
1D Co3O4/α-Fe2O3 core–shell nanofibers were successfully fabricated by a facile and template-free coaxial electrospinning method, and developed for acetone gas detection. Morphology and component characterizations confirm that the as-prepared 1D heterostructures possess a well-defined core–shell structure with Co3O4 in the core and α-Fe2O3 in the shell. The unique 1D core–shell nanostructures, heterojunction effect at the Co3O4/α-Fe2O3 interfaces and the catalysis of Co3O4 endow the Co3O4/α-Fe2O3 core–shell nanofiber-based sensor with an enhanced gas sensing performance in terms of good sensing selectivity, high sensitivity (11.7), rapid response/recovery times (2 s/20 s) and better reproducibility for acetone gas. The gas sensing mechanism is proposed in detail. Overall, the 1D Co3O4/α-Fe2O3 core–shell heterostructure nanofibers synthesized through coaxial electrospinning make a promising and effective acetone sensor.
Co-reporter:Sen Liu, Ziying Wang, Yong Zhang, Chunbo Zhang, Tong Zhang
Sensors and Actuators B: Chemical 2015 211() pp: 318-324
Publication Date(Web):
DOI:10.1016/j.snb.2015.01.127
Co-reporter:Haixia Mei, Ce Zhang, Rui Wang, Jianchao Feng, Tong Zhang
Sensors and Actuators A: Physical 2015 Volume 233() pp:118-124
Publication Date(Web):1 September 2015
DOI:10.1016/j.sna.2015.06.009
•Flexible pressure-sensitive composites with high sensitivity and quick response.•The linearity of work curve is very good when the impedance’s logarithm changes with the applied load at optimal operating frequency (1 KHz).•AC electric field is more applicable operation condition for the soft pressure sensor of silicon rubber composites.•Dielectric polarization theory is used to explain the sensitive behavior of the pressure sensor.•Internal structure diagrams of CB/SR composites were used to explain the positive pressure coefficient of resistive (PPCR) effect and negative pressure coefficient of capacitive (NPCC) effect.The surface pressure-sensitive characteristics of carbon black/silicon rubber (CB/SR) composites with positive pressure coefficient of impedance (PPCI) effect were researched. The linearity is very good when the impedance’s logarithm changes with the applied load at optimal operating frequency (1 KHz). The pressure sensor based on the flexible composites exhibit fast response when pressures are applied and canceled with a response time of 3 s. The sensor appears a higher sensitivity in AC electrical field than that in DC electrical field. Dielectric polarization theory was used to explain the sensitive behavior of the pressure sensor. Internal structure diagrams of CB/SR composites were used to explain the positive pressure coefficient of resistive (PPCR) effect and negative pressure coefficient of capacitive (NPCC) effect. AC electric field is applicable for the flexible pressure sensor based on conductive silicon rubber composites.
Co-reporter:Haixia Mei, Rui Wang, Ziying wang, Jianchao Feng, Yan Xia, Tong Zhang
Sensors and Actuators A: Physical 2015 Volume 222() pp:80-86
Publication Date(Web):1 February 2015
DOI:10.1016/j.sna.2014.11.014
•A flexible pressure-sensitive array based on soft substrate PET/ITO is designed.•The size of the 4 × 4 pressure-sensitive array is 2.5 cm × 2.5 cm × 0.8 mm.•The array shows giant NPCR effect and high sensitivity and fast response-recovery speed.•The designed structure could effectively reduce the complexity of device structure and thus makes it easy to fabricate large-area array.•The discrete distribution of the sensing elements and the test circuit make sure that there is no crosstalk among the sensing elements.A 4 × 4 flexible pressure-sensitive array based on PET/ITO (polyethylene terephthalate/indium tin oxides) was designed and fabricated, with a size of 2.5 cm × 2.5 cm × 0.75 mm. The design effectively reduces the complexity of device structure. The array shows giant negative pressure coefficient of resistivity (NPCR) effect under 0–4 N (0–0.32 M Pa). The pressure-sensitive array exhibits high sensitivity and fast response-recovery to loads. And the response and recovery times are less than 2 s. The sensitive size and azimuth of the applied loading on the pressure-sensitivity array can be accurately recognized easily. The pressure-sensitivity array is stable, low-cost and easy for fabricating large-area sensors. The designed micro array may be used for in robot skin.
Co-reporter:Lili Wang, Jianan Deng, Zheng Lou and Tong Zhang
Journal of Materials Chemistry A 2014 vol. 2(Issue 26) pp:10022-10028
Publication Date(Web):11 Mar 2014
DOI:10.1039/C4TA00651H
Quasi-1D nanofibers with heterostructure were prepared via a simple two-step process called the electrospinning technique and hydrothermal process. The nanostructures exhibit the unique feature of TiO2 nanofibers (250 nm) kept inside and well-structured Co3O4 octahedral nanoparticles loading outside. The cross-linked Co3O4/TiO2 nanostructures exhibit intriguing morphologies, architectures and chemical compositions. As a potential sensing material in chemosensor applications, the quasi-1D heterostructure nanofibers exhibit a relatively high catalysis response to CO, and good CO-sensing performance even exposure to a humid environment.
Co-reporter:Jianan Deng, Lili Wang, Zheng Lou and Tong Zhang
Journal of Materials Chemistry A 2014 vol. 2(Issue 24) pp:9030-9034
Publication Date(Web):11 Mar 2014
DOI:10.1039/C4TA00160E
A new type of quasi-1D nanofiber architecture with a heterostructure was prepared via a combination of electrospinning and hydrothermal strategies in the case of CuO–TiO2, which required a low operating temperature, and showed a high response and excellent selectivity to formaldehyde and ethanol gases.
Co-reporter:Sen Liu, Bo Yu, Feng Li, Ye Ji, Tong Zhang
Electrochimica Acta 2014 Volume 141() pp:161-166
Publication Date(Web):20 September 2014
DOI:10.1016/j.electacta.2014.07.033
Au-loading SnO2 hollow microtubes (Au-SnO2-MTs) have been successfully prepared by the coaxial electrospinning method, where the sol solution containing poly-vinylpyrrolidone and metal salts were used as outer solution and paraffin was used as inner solution, respectively. The combined characterizations of scanning electron microscopy and X-ray diffraction indicating the successful preparation of Au-SnO2-MTs with the diameter of MTs about 500-600 nm, and the thickness of the hollow MTs about 70-80 nm. It is also found that the Au-SnO2-MTs exhibit catalytic activity for electrochemical reduction of H2O2, leading to a non-enzymatic H2O2 sensor. The H2O2 sensor thus obtained shows the linear detection range from 10 μM to 1 mM (r = 0.997), and the detection limit about 0.60 μM at a signal-to-noise ratio of 3. Furthermore, the H2O2 sensor also exhibits excellent selectivity for H2O2 in comparison to other normally co-existing electroactive species (such as dopamine, ascorbic acid, uric acid and glucose) and inorganic anions.
Co-reporter:Jing Cao, Ziying Wang, Rui Wang and Tong Zhang
CrystEngComm 2014 vol. 16(Issue 33) pp:7731-7737
Publication Date(Web):24 Jun 2014
DOI:10.1039/C4CE00969J
We report a facile and efficient electrostatic spray route to fabricate novel Cr-loaded NiO core-in-hollow-shell structured micro/nanospheres without any templates or surfactants. On the basis of different influencing factors including solvent evaporation rate and temperature-dependent solute degradation process, a multistage reaction mechanism for the formation of core-in-hollow-shell micro/nanospheres is proposed. The gas sensing properties of Cr-loaded NiO sensors toward xylene gas are systematically investigated. The loading ratio of Cr has been varied and the Cr-loaded NiO sensor prepared with an optimum ratio of Cr (1.5 wt%) is found to exhibit enhanced gas sensitivity (Rg/Ra = 20.9) toward 5 ppm xylene gas at an operating temperature of 220 °C in comparison with the pure NiO sensor (Rg/Ra = 1.1). The sensor based on 1.5 wt% Cr-loaded NiO presents 20 times higher sensitivities than the sensor based on pure NiO, which is important for low concentration (1–10 ppm) xylene gas detection. Moreover, we find that the Cr-loaded NiO sensors have excellent selectivity toward xylene gas over other gases while pure NiO sensors show no selectivity toward any specific gas. The decrease in the hole concentration in NiO and the catalytic oxidation of methyl groups by Cr loading evidently play key roles in enhancing the sensitivity and greatly improving the selectivity for xylene gas. The possible gas sensing mechanism of NiO core-in-hollow-shell micro/nanospheres sensors is discussed. The facile preparation method may provide an easy path to the extendable synthesis of other functional materials with core-in-hollow-shell structured micro/nanospheres.
Co-reporter:Kai Jiang, Teng Fei and Tong Zhang
RSC Advances 2014 vol. 4(Issue 54) pp:28451-28455
Publication Date(Web):13 May 2014
DOI:10.1039/C4RA02763A
A microporous organic polymer based on 1,3,5-trihydroxybenzene was synthesized, and the structure and properties of the resultant polymeric organic framework (POF) were determined by a series of characterizations. The POF acted as a host to load different amounts of LiCl for the preparation of humidity sensitive materials. Compared with the pure POF sensor, the LiCl/POF sensors showed improved humidity sensitive properties, especially the 4 wt% LiCl/POF sensor. The impedance of the optimum sensor changed by three orders of magnitude, with good linearity over the whole humidity range. Moreover, the optimum sensor showed little hysteresis, good long-term stability and a rapid response time. In order to explore the conductive mechanism, the complex impedance plots of the optimum sensor were discussed.
Co-reporter:Hao Zhang, LiLi Wang and Tong Zhang
RSC Advances 2014 vol. 4(Issue 101) pp:57436-57441
Publication Date(Web):22 Oct 2014
DOI:10.1039/C4RA10474A
The reduced graphene oxide/SnO2/Au (rGO/SnO2/Au) hybrid nanomaterials have been prepared by a one-step hydrothermal process with a property of gas sensing at a relatively low operating temperature. The structure and morphology characteristics of the resultant product were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). The sizes of the Au nanoparticles of rGO/SnO2/Au-1 to rGO/SnO2/Au-4 range from about 12 to 90 nm, respectively. To demonstrate the usage of such hybrid nanomaterials, chemical gas sensors have been fabricated and investigated for NO2 detection. It is found that the rGO/SnO2/Au sensor exhibits much better response/recovery time which is 19/20 s at the optimal operating temperature of 50 °C to 5 ppm NO2, compared with the pure rGO (798/8319 s) and rGO/SnO2 (427/908 s). The enhanced sensing features can be attributed to the heterojunctions with the highly conductive graphene, SnO2 thin film and Au nanoparticles.
Co-reporter:Kai Jiang, Teng Fei and Tong Zhang
RSC Advances 2014 vol. 4(Issue 81) pp:43189-43194
Publication Date(Web):05 Sep 2014
DOI:10.1039/C4RA04890C
A crosslinked polyelectrolyte was synthesized by reaction of lithium benzene-1,3,5-tris(olate) and terephthalic aldehyde using a one-step hydrothermal process. The structure and morphology of the resultant polymer poly(lithium benzene-1,3,5-tris(olate)) (PLBTO) were investigated by Fourier transform infrared spectrum (FTIR), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A humidity sensor based on PLBTO was fabricated and humidity sensitive properties were explored. The impedance of PLBTO sensor changed four orders of magnitude with a good linearity over a relative humidity (RH) range from 33% to 95%. The conductive mechanism of the sensor was discussed based on complex impedance plots. The results indicate the quantity of adsorption water molecules would determine the category of conductive particles, and cause the impedance change under different RH. Moreover, the PLBTO sensor showed little hysteresis, rapid response/recovery and good long-term stability, which have benefited from the crosslinked structure of PLBTO.
Co-reporter:Sen Liu, Ziying Wang, Fengjiao Wang, Bo Yu and Tong Zhang
RSC Advances 2014 vol. 4(Issue 63) pp:33327-33331
Publication Date(Web):18 Jul 2014
DOI:10.1039/C4RA04700A
A highly sensitive and selective non-enzymatic glucose biosensor has been successfully constructed using high surface area mesoporous CuO (108 m2 g−1) templated by mesoporous carbon. The glucose biosensor exhibits a low detection limit of 0.23 μM at a signal-to-noise ratio of 3.
Co-reporter:Teng Fei, Kai Jiang, Sen Liu and Tong Zhang
RSC Advances 2014 vol. 4(Issue 41) pp:21429-21434
Publication Date(Web):07 May 2014
DOI:10.1039/C4RA01389A
A humidity sensitive polymer was synthesized based on the derivative of triphenylphosphine by Friedel–Crafts alkylation. The polymer was formed of a hydrophobic skeleton with hydrophilic ions modified on phosphorous atoms evenly. The resultant polymer shows nanoporous characteristics. A humidity sensor based on the amphiphilic porous polymer shows unexpectedly good sensing properties, including high sensitivity, small humidity hysteresis, rapid response and recovery, and good stability. The good stability of the sensor is attributed to the cross-linked skeleton structure of the polymer, even though the content of ions in the polymer is high. These results demonstrate that porous polymers modified with certain hydrophilic groups are promising materials for high performance humidity sensors.
Co-reporter:Jianan Deng, Lili Wang, Zheng Lou and Tong Zhang
RSC Advances 2014 vol. 4(Issue 40) pp:21115-21120
Publication Date(Web):28 Apr 2014
DOI:10.1039/C4RA02065K
A new type of comb-like architecture with a hierarchical structure was prepared via a simple and effective hydrothermal strategy in the case of Co3O4. FESEM and TEM confirm the comb-like architecture of the hierarchical structure, and that the Co3O4 nanorods with secondary nanostructures are the building units. The studies of the sensing performance demonstrate that the as-synthesized comb-like Co3O4 nanostructures show excellent catalytic activity upon exposure to CO gases in comparison with rod-like Co3O4. Importantly, the comb-like Co3O4 nanostructure-based sensor shows a fast response and recovery speed for CO gas. It is believed that the strategy of combining the hierarchical nanostructure and catalytic activity of Co3O4 nanomaterials can further provide potential for applications as real-time monitoring gas sensors.
Co-reporter:Yan Xia, Hongran Zhao, Sen Liu and Tong Zhang
RSC Advances 2014 vol. 4(Issue 6) pp:2807-2812
Publication Date(Web):27 Nov 2013
DOI:10.1039/C3RA45339A
One-dimensional MCM-48 mesoporous silica materials were successfully synthesized by a colloid electrospinning method combined with subsequent heat treatment. The structures were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and N2 adsorption–desorption. The results revealed that the fibers were made up of MCM-48 mesoporous silica nanoparticles with diameters of 100–150 nm. The fibers kept the 3D ordered mesoporous structure of MCM-48 nanoparticles. The humidity sensors based on the as-synthetized materials exhibited good linearity, small hysteresis and rapid response–recovery time. The possible mechanism of the difference in humidity sensing performance was discussed through the complex impedance plots.
Co-reporter:Sen Liu, Bo Yu and Tong Zhang
RSC Advances 2014 vol. 4(Issue 2) pp:544-548
Publication Date(Web):06 Nov 2013
DOI:10.1039/C3RA44492A
Nitrogen-doped carbon nanodots (CDs) were found to possess reductive activity and could catalytically reduce AgNO3 to produce Ag nanoparticles (AgNPs). The AgNPs reduced by CDs (AgNPs-CDs) exhibit better catalytic activity toward electrochemical reduction of H2O2 than that of AgNPs reduced by NaBH4 (AgNPs-SB) and sodium citrate (AgNPs-SC), leading to a high-performance non-enzymatic H2O2 sensor. The linear detection range is estimated to be from 0.1 mM to 60 mM (r = 0.999), and the detection limit is estimated to be 0.5 μM at a signal-to-noise ratio of 3.
Co-reporter:Xiaoju Luo, Zheng Lou, Lili Wang, Xuejun Zheng and Tong Zhang
New Journal of Chemistry 2014 vol. 38(Issue 1) pp:84-89
Publication Date(Web):02 Oct 2013
DOI:10.1039/C3NJ00776F
Nanosheet-assembled hierarchical flower-like ZnO nanostructures formed from closely packed nanosheets have been fabricated from an ethanol-assisted hydrothermal route at a temperature of 140 °C. It was found that the solvent played a key role in the formation process of the hierarchical ZnO nanostructures in this reaction system. Most importantly, the as-prepared nanosheet-assembled flower-like ZnO (S-1) nanostructures exhibited excellent sensing properties towards acetone, up to 35.1 within 0.5 s towards 500 ppm acetone, which were much better than those of nanorod-assembled flower ZnO nanostructures (S-2) and ZnO microspheres (S-3). A detailed investigation revealed that a large number of almost invisible pores existed in the ZnO superstructures, which play a key role in the transport pathways of small molecules, resulting in nanosheets with a high level of sensing activity.
Co-reporter:Teng Fei;Kai Jiang;Fan Jiang;Ren Mu
Journal of Applied Polymer Science 2014 Volume 131( Issue 1) pp:
Publication Date(Web):
DOI:10.1002/app.39726
ABSTRACT
Multiwalled carbon nanotubes (CNTs) were used as the conductive filler of composites for switching type humidity sensor. The CNTs were oxidized by mixed acids (H2SO4 : HNO3) at a mild temperature to modify carboxylic acid (COOH) groups on the surface of the nanotubes. The dispersibility of acid treated CNTs (CNTs-COOH) in water is much improved, which is beneficial for dispersing CNTs in the polyvinyl alcohol (PVA) matrix without external additives. The obtained CNTs-COOH/PVA sensors show nonlinear response to relative humidity (RH), that is, switching properties. The resistances of the sensors remain constant before 80% relative humidity (RH) and then increase sharply with RH, indicating excellent switching characteristic of the sensors. The 10 wt % CNTs-COOH/PVA sensor shows a sensitivity (ΔR/Ro) of 32.3 at 100% RH. The humidity switching properties of CNTs-COOH/PVA are much better than that of pristine CNTs/PVA. The improvements are attributed to the improved balance between the dispersibility of CNTs-COOH and electrical conductivity of the composite films. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39726.
Co-reporter:Hao Zhang, Jianchao Feng, Teng Fei, Sen Liu, Tong Zhang
Sensors and Actuators B: Chemical 2014 190() pp: 472-478
Publication Date(Web):
DOI:10.1016/j.snb.2013.08.067
Co-reporter:Sen Liu, Ziying Wang, Hongran Zhao, Teng Fei, Tong Zhang
Sensors and Actuators B: Chemical 2014 197() pp: 342-349
Publication Date(Web):
DOI:10.1016/j.snb.2014.03.007
Co-reporter:Kai Jiang, Teng Fei, Fan Jiang, Guan Wang, Tong Zhang
Sensors and Actuators B: Chemical 2014 192() pp: 658-663
Publication Date(Web):
DOI:10.1016/j.snb.2013.11.004
Co-reporter:Teng Fei, Kai Jiang, Sen Liu, Tong Zhang
Sensors and Actuators B: Chemical 2014 190() pp: 523-528
Publication Date(Web):
DOI:10.1016/j.snb.2013.09.013
Co-reporter:Teng Fei, Kai Jiang, Tong Zhang
Sensors and Actuators B: Chemical 2014 199() pp: 148-153
Publication Date(Web):
DOI:10.1016/j.snb.2014.03.088
Co-reporter:Kai Jiang, Teng Fei, Tong Zhang
Sensors and Actuators B: Chemical 2014 199() pp: 1-6
Publication Date(Web):
DOI:10.1016/j.snb.2014.03.047
Co-reporter:Jing Cao, Huimin Dou, Hao Zhang, Haixia Mei, Sen Liu, Teng Fei, Rui Wang, Lijie Wang, Tong Zhang
Sensors and Actuators B: Chemical 2014 198() pp: 180-187
Publication Date(Web):
DOI:10.1016/j.snb.2014.03.015
Co-reporter:Sen Liu, Bo Yu and Tong Zhang
Journal of Materials Chemistry A 2013 vol. 1(Issue 42) pp:13314-13320
Publication Date(Web):23 Aug 2013
DOI:10.1039/C3TA12594G
In this work, reduced graphene oxide–poly(p-phenylenediamine) (rGO–PpPD) hybrids have been successfully prepared through a facile and effective method by heat treatment of GO aqueous dispersion in the presence of pPD at 80 °C for 2 h. The combined characterization by scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) indicates the successful production of rGO–PpPD hybrids with a crumpled morphology. The formation of rGO–PpPD hybrids is attributed to the redox reactions between GO and pPD, where the reduction of GO to rGO and polymerization of pPD into PpPD occurred simultaneously. It was found that rGO–PpPD hybrids show good catalytic activity toward oxidation of dopamine (DA), and no response to ascorbic acid (AA) and uric acid (UA), leading to a high-performance DA sensor. The linear detection ranges are estimated to be from 5 μM to 25 μM (r = 0.998) and 50 μM to 200 μM (r = 0.995), respectively. The detection limit is estimated to be 0.36 μM at a signal-to-noise ratio of 3.
Co-reporter:Lili Wang, Huimin Dou, Zheng Lou and Tong Zhang
Nanoscale 2013 vol. 5(Issue 7) pp:2686-2691
Publication Date(Web):03 Dec 2012
DOI:10.1039/C2NR33088A
New Au@SnO2 yolk–shell nanospheres have been successfully synthesized by using Au@SiO2 nanospheres as sacrificial templates. This process is environmentally friendly and is based on hydrothermal shell-by-shell deposition of polycrystalline SnO2 on spheriform Au@SiO2 nanotemplates. Au nanoparticles can be impregnated into the SnO2 nanospheres and the nanospheres show outer diameters of 110 nm and thicknesses of 15 nm. The possible growth model of the nanospheres is proposed. The gas sensing properties of the Au@SnO2 yolk–shell nanospheres were researched and compared with that of the hollow SnO2 nanospheres. The former shows lower operating temperature (210 °C), lower detection limit (5 ppm), faster response (0.3 s) and better selectivity. These improved sensing properties were attributed to the catalytic effect of Au, and enhanced electron depletion at the surface of the Au@SnO2 yolk–shell nanospheres.
Co-reporter:Zheng Lou, Feng Li, Jianan Deng, LiLi Wang, and Tong Zhang
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 23) pp:12310
Publication Date(Web):October 8, 2013
DOI:10.1021/am402532v
A novel hierarchical heterostructure of α-Fe2O3 nanorods/TiO2 nanofibers with branch-like nanostructures was fabricated using a simple two-step process called the electrospinning technique and hydrothermal process. A high density of α-Fe2O3 nanorods (about 200 nm in diameter) was uniformly deposited on a TiO2 nanofibers backbone. The phase purity, morphology, and structure of hierarchical heterostructures are investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and energy-dispersive X-ray (EDX) analysis. The highly branched α-Fe2O3/TiO2 heterostructures provided an extremely porous matrix and high specific surface area required for high-performance gas sensors. Different nanostructured α-Fe2O3/TiO2 heterostructures are also investigated by controlling the volume ratio of the reactants. The α-Fe2O3/TiO2 heterostructures with a proper mixture ratio of the reactants sensor exhibit obviously enhanced sensing characteristics, including higher sensing response, lower operating temperature, faster response speed, and better selectivity in comparison with other ones. Moreover, the α-Fe2O3/TiO2 heterostructures sensor also exhibits excellent sensing performances compared with α-Fe2O3 nanorods and TiO2 nanofibers sensors. Thus, the combination of TiO2 nanofibers backbone and α-Fe2O3 nanorods uniformly decorated endows a fascinating sensing performance as a novel sensing material with high response and rapid responding and recovering speed.Keywords: hierarchical heterostructures; high response; TMA sensing; α-Fe2O3/TiO2;
Co-reporter:Sen Liu, Bo Yu, Tong Zhang
Electrochimica Acta 2013 Volume 102() pp:104-107
Publication Date(Web):15 July 2013
DOI:10.1016/j.electacta.2013.03.191
•NiO hollow spheres have been prepared by a one-pot hydrothermal synthesis route.•A non-enzymatic glucose sensor based on NiO hollow spheres has been constructed.•The glucose sensor exhibits high sensitivity and selectivity for glucose detection.A novel non-enzymatic glucose sensor has been constructed by using NiO hollow spheres (NiO-HSs) as sensing materials, which were prepared by a glycerin-assisted hydrothermal synthesis method. The analytical techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) indicate the successful formation of NiO-HSs, assembled by NiO nanoflakes with the length of about 500 nm and the width of about 50 nm. It was found that the resulting NiO-HSs exhibit good catalytic activity toward the oxidation of glucose in 0.1 M NaOH, leading to a non-enzymatic glucose sensor with a fast amperometric response time of less than 3 s, and the detection limit is estimated to be 0.3 μM at a signal-to-noise ratio of 3. Furthermore, this sensor shows good response to glucose in comparison to other normally co-existing electroactive species (such as dopamine, ascorbic acid and uric acid).
Co-reporter:Lili Wang, Xiaoju Luo, Xuejun Zheng, Rui Wang and Tong Zhang
RSC Advances 2013 vol. 3(Issue 25) pp:9723-9728
Publication Date(Web):09 Apr 2013
DOI:10.1039/C3RA41032C
Hollow stannic oxide (SnO2) nanofibers were fabricated by direct annealing of electrospun precursor nanofibers. In this approach, different SnO2 nanostructures were synthesized by electrospinning a PVP/salt solution, and then calcining at a high temperature with an appropriate heating rate. The nanofibers were identified as hollow in structure, with diameters ranging from 80 to 100 nm and a wall thickness up to about 20 nm. The gas sensor based on hollow SnO2 nanofibers exhibits a high response and a quick response-recovery to carbon tetrachloride, which is much better than that of solid SnO2 nanofibers. It is believed that its high gas sensing performance is derived from the large surface area, and high porosity, which lead to highly effective surface interactions between the target gas molecules and the surface active sites.
Co-reporter:Zheng Lou, Jianan Deng, Lili Wang, Rui Wang, Teng Fei and Tong Zhang
RSC Advances 2013 vol. 3(Issue 9) pp:3131-3136
Publication Date(Web):21 Dec 2012
DOI:10.1039/C2RA22655C
Combining the versatility of the electrospinning technique and the hydrothermal growth of nanostructures enabled the fabrication of TiO2/ZnO composite nanostructures. XRD, FESEM, TEM and EDX analysis confirmed the growth of ZnO nanosheets with a diameter of about 500 nm on the surface of TiO2 nanofibers. Gas sensing properties of the sensors fabricated from the as-prepared TiO2/ZnO, TiO2 and ZnO were systematically investigated. The TiO2/ZnO sensor exhibits a response of 15.7 to 100 ppm of ethanol at 280 °C, which is much better than pure TiO2 and ZnO. The enhanced sensing performance to ethanol is mainly attributed to the formation of heterojunctions between TiO2 and ZnO, which leads to the interfacial transport of excess carriers.
Co-reporter:Bo Yu, Jianchao Feng, Sen Liu and Tong Zhang
RSC Advances 2013 vol. 3(Issue 34) pp:14303-14307
Publication Date(Web):28 Jun 2013
DOI:10.1039/C3RA41755G
Reduced graphene oxide (rGO) decorated with high density Ag nanorods has been prepared by reduction of GO and AgNO3 using ethylene glycol as reducing agent and solvent. The resulting hybrids exhibit good performance for the non-enzymatic detection of hydrogen peroxide, with a linear detection range of 0.1 to 70 mM (r = 0.9996), and a detection limit of 2.04 μM at a signal-to-noise ratio of 3.
Co-reporter:Teng Fei;Hongran Zhao;Kai Jiang;Xing Zhou
Journal of Applied Polymer Science 2013 Volume 130( Issue 3) pp:2056-2061
Publication Date(Web):
DOI:10.1002/app.39400
ABSTRACT
A class of humidity sensors with switching property based on several hydrophilic polymers [poly(N-vinyl-2-pyrrolidone) (PVP), poly(vinyl alcohol) (PVA), and hydroxyethyl cellulose (HEC)] were researched. These polymers were selected as the sensing materials because the polar groups in the molecules (amide, hydroxyl, and ether bond) could interact with water molecules. The sensors all show nonlinear response to relative humidity (RH) under AC voltage. The impedances of the sensors remain almost unchanged at low RH and decrease sharply at certain humidity (about 75, 65, and 55% RH for PVP, PVA, and HEC sensors, respectively). The switching points and sensitivities of the sensors could be adjusted by changing the operating frequency, polymer blending, or doping with hydrophilic materials. The complex impedances of the sensors demonstrate that the electronic contribution is dominant at low RH, and the ions make a significant contribution for increasing RH levels. The different sensing properties of the polymers are attributed to their different hydrophilic properties and ionic contributions at high RH. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2056–2061, 2013
Co-reporter:Hang Liu, Hui-Tao Fan, Xiu-Juan Xu, Hangxin Lu, Tong Zhang
Solid-State Electronics 2013 Volume 79() pp:87-91
Publication Date(Web):January 2013
DOI:10.1016/j.sse.2012.07.004
LaxSr1−xFeO3 nanofibers were synthesized via electrospinning and characterized by field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The diameters of the LaxSr1−xFeO3 nanofibers produced were in the range of 30–80 nm. When the La/Sr ratio was 0.7:0.3, La0.7Sr0.3FeO3 nanofibers showed high and rapid response and good repeatability to 500 ppm ethanol. At 185 °C, the response and recovery time of La0.7Sr0.3FeO3 nanofiber were 11 s and 21 s, respectively. The La0.7Sr0.3FeO3 nanofibers are promising sensitive materials for ethanol detecting.Highlights► We prepared LaxSr1−xFeO3 (x = 0.6, 0.7, 0.8) nanofibers via electrospinning method. ► We fabricated indirect-heating sensors based on the obtained nanofibers. ► We measured gas sensing properties of the LaxSr1−xFeO3 based sensors. ► The La0.7Sr0.3FeO3nanofibers showed good ethanol sensing properties.
Co-reporter:Lili Wang, Huimin Dou, Feng Li, Jianan Deng, Zheng Lou, Tong Zhang
Sensors and Actuators B: Chemical 2013 Volume 183() pp:467-473
Publication Date(Web):5 July 2013
DOI:10.1016/j.snb.2013.03.129
Hollow ZnO microspheres with tunable interior architecture are successfully synthesized by a simple green chemistry routes at low temperature. This process is environmentally friendly processing, which based on without using solvents, employing carbon microspheres as template and reaction at low temperature. The layer-control of hollow ZnO microspheres can be easily adjusted by varying the concentration of the zinc precursor added. To demonstrate the usage of such hollow ZnO microspheres, gas sensors have been fabricated from the as-synthesized hollow ZnO microspheres with different shelled and investigated for formaldehyde (HCHO) detection. Interestingly, the response of hollow ZnO microspheres increased with increasing the number of shell structures. These results indicate that three-shelled ZnO sensor displays about 1.5 and 3–4 fold enhancement in response compared to double and single-shelled one, respectively. The mechanism of enhanced sensor performances is also proposed.
Co-reporter:Zheng Lou, Jianan Deng, Lili Wang, Lijie Wang, Teng Fei, Tong Zhang
Sensors and Actuators B: Chemical 2013 176() pp: 323-329
Publication Date(Web):
DOI:10.1016/j.snb.2012.09.027
Co-reporter:Jianan Deng, Bo Yu, Zheng Lou, Lili Wang, Rui Wang, Tong Zhang
Sensors and Actuators B: Chemical 2013 Volume 184() pp:21-26
Publication Date(Web):31 July 2013
DOI:10.1016/j.snb.2013.04.020
Three-dimensional brush-like ZnO–TiO2 hierarchical heterojunctions nanofibers have been successfully obtained by the combination of the electrospinning and hydrothermal process. The FESEM images showed that the brush-like ZnO–TiO2 hierarchical heterojunctions nanofibers are composed of uniform ZnO nanorods layer of approximately 100–300 nm in diameter grown on the side surface of TiO2 core nanofibers. The gas sensing studies revealed that the ZnO–TiO2 sensors exhibited enhanced sensing performance to ethanol compared with the pristine TiO2 nanofibers and pristine ZnO nanorods, which might be attributed to the unique hierarchical structure and great degree of electron depletion of the interface based on the synergistic effect among the two components of TiO2 and ZnO.
Co-reporter:Zheng Lou, Jianan Deng, Lili Wang, Lijie Wang, Tong Zhang
Sensors and Actuators B: Chemical 2013 Volume 182() pp:217-222
Publication Date(Web):June 2013
DOI:10.1016/j.snb.2013.02.091
Self-assembled curling-like Bi2WO6 microdiscs, consisting of closely packed nanosheets with thickness of 50 nm, have been successfully synthesized by a simple solvothermal route. This structure was characterized by field emission scanning electron microscopic (FESEM) and transmission electron microscopy (TEM). The results show that the Bi2WO6 samples are mostly microdiscs in shape and have an average side thickness of 500 nm. The time-dependent morphology of the Bi2WO6 samples has been investigated, and gas sensors based on these products were fabricated for ethanol detection. The sensor based on the curling-like Bi2WO6 nanostructures shows much better sensing properties than other Bi2WO6 structures. The response of the curling-like Bi2WO6 sensor to 100 ppm ethanol is about 11.9 with the response time of 1 s. The dramatic improvement in sensing properties of the present curling-like Bi2WO6 sensor may be attributed to the unique structures, the good crystallization and large surface area.
Co-reporter:Lili Wang, Teng Fei, Jianan Deng, Zheng Lou, Rui Wang and Tong Zhang
Journal of Materials Chemistry A 2012 vol. 22(Issue 35) pp:18111-18114
Publication Date(Web):22 Jun 2012
DOI:10.1039/C2JM32520A
A new type of rattle-type structure with a porous shell was prepared via a simple template strategy in the case of SnO2, which showed high response and good selectivity to ethanol.
Co-reporter:Lili Wang, Zheng Lou, Rui Wang, Teng Fei and Tong Zhang
Journal of Materials Chemistry A 2012 vol. 22(Issue 25) pp:12453-12456
Publication Date(Web):09 May 2012
DOI:10.1039/C2JM16509K
A new type of ring-like architecture with a lamellar structure was prepared via a simple hydrothermal strategy in the case of PdO–NiO, which showed a low operating temperature, a high response and rapid response/recovery to CO gas.
Co-reporter:Lili Wang, Zheng Lou, Teng Fei and Tong Zhang
Journal of Materials Chemistry A 2012 vol. 22(Issue 11) pp:4767-4771
Publication Date(Web):30 Jan 2012
DOI:10.1039/C2JM15342D
Au-loaded ZnO hollow nanospheres have been successfully synthesized by using carbon nanospheres as sacrificial templates. This simple strategy could be expected to be extended for the fabrication of similar metal–oxide loaded hollow nanospheres using different precursors. The structural and morphological characteristics of the resultant product were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The hollow nanospheres are porous, with the diameters ranging from 220 to 280 nm. To demonstrate the usage of such Au-loaded ZnO nanomaterial, a chemical gas sensor has been fabricated and investigated for NH3 detection. The Au-loaded ZnO sensor exhibits excellent sensing performances compared with hollow ZnO and compact ZnO sensors. The dynamic transients of the Au-loaded ZnO sensors demonstrated both their fast response (0.8–1.5 s) and recovery (3–4 s) towards NH3 gases. The combination of ZnO hollow structure and catalytic activity of Au loaded gives a very attractive sensing behavior for applications as real-time monitoring gas sensors with fast responding and recovering speed.
Co-reporter:Zheng Lou, Lili Wang, Teng Fei and Tong Zhang
New Journal of Chemistry 2012 vol. 36(Issue 4) pp:1003-1007
Publication Date(Web):08 Feb 2012
DOI:10.1039/C2NJ21030D
A novel sensing material of NiO-doped SnO2 polyhedra was prepared and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) spectroscopy and transmission electron microscopy (TEM). Gas sensing properties of the sensor fabricated from the as-prepared NiO-doped SnO2 were systematically investigated and compared with those of pure SnO2. The NiO-doped SnO2 sensor exhibits a response of 6.7 to 30 ppm ethanol at 280 °C with the response and recovery times shorter than 0.6 and 10 s, respectively, which are much better than pure SnO2. The enhanced sensing performances to ethanol are mainly attributed to the formation of p–n heterojunctions between p-type NiO and n-type SnO2 and the increased alkalinity of SnO2 by NiO doping.
Co-reporter:Yan Xia, Teng Fei, Yuan He, Rui Wang, Fan Jiang, Tong Zhang
Materials Letters 2012 Volume 66(Issue 1) pp:19-21
Publication Date(Web):1 January 2012
DOI:10.1016/j.matlet.2011.08.069
Ba0.8Sr0.2TiO3/Poly (vinylpyrrolidone) (BST/PVP) composite fibers were successfully synthesized via electrospinning. The ceramic nanofibers were obtained after calcining the composite at 800 °C for 2 h. The morphology and structure of the BST fibers were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results reveal that the as-synthesized BST nanofibers show a diameter of 50–150 nm with the length over 0.1 mm, and a well-defined perovskite crystal structure. The electrical properties of the as-synthesized BST nanofibers were investigated through an impedance-type humidity sensor. The nanofibers exhibited excellent humidity sensing properties at room temperature. The possible sensing mechanism was proposed.Research Highlights► We synthesized the BST ceramic nanofibers via electrospinning and calcination method. ► We fabricated a humidity sensor based on as-synthesized BST nanofibers. ► The sensor exhibited excellent humidity sensing properties at room temperature.
Co-reporter:Yan Xia, Yuan He, Rui Wang, Jianchao Feng, Tong Zhang
Materials Letters 2012 Volume 88() pp:43-46
Publication Date(Web):1 December 2012
DOI:10.1016/j.matlet.2012.08.038
Uniaxially aligned Ba0.8Sr0.2TiO3 (BST) nanofiber arrays were fabricated via electrospinning combined with annealing. A specially designed collector composed of two paralleled aluminum electrodes and an insulative substrate were used in the electrospinning process. The morphology and structure of the resultant arrays were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The SEM shows well uniaxial arrangement and the diameters before (300–500 nm) and after (100 nm) calcination. XRD shows well-defined perovskite crystal structure of the as-synthesized arrays. The humidity sensor based on the as-synthesized arrays exhibited a rapid response-recovery property at room temperature. The possible sensing mechanism was proposed.Highlights► We synthesized the BST aligned nanofibers arrays via electrospinning and calcination. ► We fabricated a humidity sensor based on BST nanofibers arrays. ► The sensor exhibited excellent humidity response property at room temperature.
Co-reporter:Zheng Lou, Lili Wang, Rui Wang, Teng Fei, Tong Zhang
Solid-State Electronics 2012 Volume 76() pp:91-94
Publication Date(Web):October 2012
DOI:10.1016/j.sse.2012.05.062
SnO2 nanosheets were synthesized by a hydrothermal method at 200 °C using stannic chloride hydrate and sodium hydroxide as starting materials. The as-synthesized nanoparticles and nanosheets are characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The gas response, selectivity, and response speed were optimized by varying the morphology of the sensing materials and operation temperature. Most importantly, the SnO2 nanosheets sensor exhibits high response, low detection limit and fast response to ethanol. The gas response of the SnO2 nanosheets to 100 ppm ethanol was 39.6 at 300 °C, which was 3.6 and 6.1 times higher than that of the nanospheres-like and the nanoparticles, respectively. Response and recovery times were 1 and 9 s when the sensor was exposed to 20 ppm ethanol at an operating temperature of 300 °C.Highlights► A sensing material of SnO2 nanosheets was prepared by a hydrothermal method. ► The sensor exhibited excellent ethanol sensing properties compared to other nanostructure. ► The excellent sensor performances are attributed to the unique structures.
Co-reporter:Lili Wang, Zheng Lou, Teng Fei, Tong Zhang
Sensors and Actuators B: Chemical 2012 Volume 161(Issue 1) pp:178-183
Publication Date(Web):3 January 2012
DOI:10.1016/j.snb.2011.10.005
Hierarchical hollow Au-loaded NiO hybrid microspheres have been synthesized with good uniformity by a surfactant-free hydrothermal route and subsequent heat treatment. This method requires high concentrations of a nickel precursor (0.2 M) and introduction of a trace amount of Au nanoparticles into the reaction system. The hierarchical hollow Au-loaded NiO hybrid microsphere comprises several nanorods and nanosheets. To demonstrate the usage of such hierarchical hybrid nanomaterials, a gas sensor has been fabricated from the as-synthesized Au-loaded NiO microspheres and investigated for acetone detection. The Au-loaded NiO sensor exhibits significantly improved sensing performances in terms of high sensitivity, low detection limit, better selectivity, rapid response, and good reproducibility in comparison with pure NiO. The effects of Au loading on the acetone-sensing properties of hierarchical NiO microspheres have been investigated.
Co-reporter:Lili Wang, Jianan Deng, Teng Fei, Tong Zhang
Sensors and Actuators B: Chemical 2012 Volume 164(Issue 1) pp:90-95
Publication Date(Web):31 March 2012
DOI:10.1016/j.snb.2012.01.063
Hollow NiO–SnO2 nanospheres have been fabricated via a simple one-pot template-free method. The synthesis is based on solvothermal treatment of stannate and nickel nitrate as the precursor in a mixed solvent of heptane–ethanol. The hollow nanospheres show diameters of about 200–300 nm with the wall thickness of about 50 nm, and the shell consists of numerous small nanoparticles. The gas sensor based on hollow NiO–SnO2 nanospheres exhibits high response and quick response–recovery to NH3, which are much better compared with sensors based on solid NiO–SnO2 nanospheres. The enhanced sensor performances are attributed to the larger surface area and fast gas diffusion.
Co-reporter:Lili Wang, Zheng Lou, Teng Fei and Tong Zhang
Journal of Materials Chemistry A 2011 vol. 21(Issue 48) pp:19331-19336
Publication Date(Web):28 Oct 2011
DOI:10.1039/C1JM13354C
A new type of spherically multilayered core–shell structure was prepared via a simple hard template strategy in the case of ZnO. The structure and morphology characteristics of the resultant product were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The ZnO microspheres with hollow interior and porous shells are multilayered structures with diameters ranging from 0.4 to 3.5 μm. Further investigation of the formation mechanism reveals that the preheating program is vital to the formation of the multishelled structures. To demonstrate the usage of such a multilayered nanomaterial, a chemical gas sensor has been fabricated and investigated for toluene detection. The sensor exhibits excellent sensing performances in terms of high response, low detection limit, rapid response-recovery, and superior selectivity.
Co-reporter:LiLi Wang, Teng Fei, Zheng Lou, and Tong Zhang
ACS Applied Materials & Interfaces 2011 Volume 3(Issue 12) pp:4689
Publication Date(Web):November 6, 2011
DOI:10.1021/am201112z
The α-Fe2O3 hierarchical nanostructures have been successfully synthesized via a simple solvothermal method. The as-prepared samples are loose and porous with flowerlike structure, and the subunits are irregularly shaped nanosheets. The morphology of the α-Fe2O3 structures was observed to be tunable as a function of reaction time. To demonstrate the potential applications, we have fabricated a gas sensor from the as-synthesized hierarchical α-Fe2O3 and investigated it for ethanol detection. Results show that the hierarchical α-Fe2O3 sensor exhibits significantly improved sensor performances in comparison with the compact α-Fe2O3 structures. The enhancement of sensing properties is attributed to the unique porous and well-aligned nanostructure.Keywords: gas sensor; hierarchical structures; rapid response; α-Fe2O3;
Co-reporter:Lijie Wang, Jiahuan Hu, Hongyu Zhang and Tong Zhang
Chemical Communications 2011 vol. 47(Issue 24) pp:6837-6839
Publication Date(Web):10 May 2011
DOI:10.1039/C1CC10882D
FETs based on Au-impregnated polyacrylonitrile (PAN)/polythiophene (PTH) core–shell nanofibers have been fabricated and exhibit high mobility (∼2.0 cm2 V−1 s−1).
Co-reporter:Ji-yan Leng, Xiu-juan Xu, Ning Lv, Hui-tao Fan, Tong Zhang
Journal of Colloid and Interface Science 2011 Volume 356(Issue 1) pp:54-57
Publication Date(Web):1 April 2011
DOI:10.1016/j.jcis.2010.11.079
WO3 nanofibers were synthesized using an electrospinning method and characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The obtained WO3 nanofibers were used as sensitive materials for the detection of NH3. Indirect-heating sensors based on WO3 nanofibers were prepared. When the WO3 nanofiber-based sensors were exposed to 100 ppm NH3 at 500 °C, the response is 5.5, and the response and recovery times are 1 and 5 s, respectively. These results indicate that the gas sensors based on WO3 nanofibers express high and fast response and recovery characteristics to NH3, and the WO3 nanofibers are promising sensitive materials for NH3 detecting.Graphical abstractThe WO3 nanofibers prepared by an electrospinning method have fast response and recovery characteristics to different concentrations of NH3.Research highlights► In this paper, we prepared WO3 nanofibers by an electrospinning method. ► We systemically studied the gas-sensing properties of this material. ► The result indicates that the gas sensors based on WO3 nanofibers express high and fast response and recovery characteristics to NH3. ► The WO3 nanofibers are promising sensitive materials for NH3 detecting.
Co-reporter:Lili Wang, Zheng Lou, Tong Zhang, Huitao Fan, Xiujuan Xu
Sensors and Actuators B: Chemical 2011 Volume 155(Issue 1) pp:285-289
Publication Date(Web):5 July 2011
DOI:10.1016/j.snb.2010.12.036
Hierarchical SnO2 microspheres were synthesized by a hydrothermal method at 140 °C using stannic chloride hydrate and sodium hydroxide as starting materials. The individual hierarchical SnO2 microsphere ranged from 700 to 900 nm in diameter. After these microspheres were heated at 600 °C for 2 h, the spheres were cross-linked into clusters by short SnO2 nanorods as revealed by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Most importantly, SnO2 hierarchical microsphere sensor exhibits excellent selectivity and fast response to ethanol. Response and recovery times were 0.6 s and 11 s when the sensor was exposed to 50 ppm ethanol at an operating temperature of 300 °C. Thus, hierarchical structures play a significant role in the field of gas sensing.
Co-reporter:Lijie Wang, Yuan He, Jiahuan Hu, Qi Qi, Tong Zhang
Sensors and Actuators B: Chemical 2011 Volume 153(Issue 2) pp:460-464
Publication Date(Web):20 April 2011
DOI:10.1016/j.snb.2010.11.016
Barium titanate (BaTiO3) nanofibers were synthesized by electrospinning and calcination techniques. Two direct current (DC) humidity sensors with different electrodes (Al and Ag) were fabricated by loading BaTiO3 nanofibers as the sensing material. Compared with the Al electrode sensor, the Ag electrode sensor exhibits larger sensitivity and quicker response/recovery. The current of Al electrode sensor increases from 4.08 × 10−9 to 1.68 × 10−7 A when the sensor is switched from 11% to 95% relative humidity (RH), while the values are 2.19 × 10−9 and 3.29 × 10−7 A for the Ag electrode sensor, respectively. The corresponding response and recovery times are 30 and 9 s for Al electrode sensor, and 20 and 3 s for Ag electrode sensor, respectively. These results make BaTiO3 nanofiber-based DC humidity sensors good candidates for practical application. Simultaneously, the comparison of sensors with different electrode materials may offer an effective route for designing and optimizing humidity sensors.
Co-reporter:Huitao Fan, Yi Zeng, Xiujuan Xu, Ning Lv, Tong Zhang
Sensors and Actuators B: Chemical 2011 Volume 153(Issue 1) pp:170-175
Publication Date(Web):31 March 2011
DOI:10.1016/j.snb.2010.10.026
Hollow ZnSnO3 microspheres were successfully prepared by hydrothermal method at 160 °C for 12 h. The prepared material was characterized by field emission scanning electron microscope (FESEM), transmission electron microscope (TEM) and X-ray diffraction measurements (XRD). The average diameter of the hollow ZnSnO3 microspheres was in the range of 400–600 nm. Compared with solid ZnSnO3 microspheres structure, the hollow ZnSnO3 microspheres showed better response (S) to butane. To 500 ppm butane, the sensor response (S) of the hollow ZnSnO3 microspheres was 5.79 at the optimum operating temperature of 380 °C, and the response and recovery time were 0.3 s and 0.65 s, respectively. The sensitivities of sensors based on this material were linear with the concentration of butane in the range of 100–1000 ppm.
Co-reporter:Huitao Fan, Tong Zhang, Xiujuan Xu, Ning Lv
Sensors and Actuators B: Chemical 2011 Volume 153(Issue 1) pp:83-88
Publication Date(Web):31 March 2011
DOI:10.1016/j.snb.2010.10.014
N-type Fe2O3 nanobelts and P-type LaFeO3 nanobelts were prepared by electrospinning. The structure and micro-morphology of the materials were characterized by X-ray diffraction (XRD) and scanning of electron microscopy (SEM). The gas sensing properties of the materials were investigated. The results show that the optimum operating temperature of the gas sensors fabricated from Fe2O3 nanobelts is 285 °C, whereas that from LaFeO3 nanobelts is 170 °C. Under optimum operating temperatures at 500 ppm ethanol, the response of the gas sensors based on these two materials is 4.9 and 8.9, respectively. The response of LaFeO3-based gas sensors behaves linearly with the ethanol concentration at 10–200 ppm. Sensitivities to different gases were examined, and the results show that LaFeO3 nanobelts exhibit good selectivity to ethanol, making them promising candidates as practical detectors of ethanol.
Co-reporter:Rui Wang;Yuan He;Xiaotian Li;Wangchang Geng;Jinchun Tu;Qing Yuan
Journal of Applied Polymer Science 2010 Volume 115( Issue 6) pp:3474-3480
Publication Date(Web):
DOI:10.1002/app.31408
Abstract
Nickel oxide (NiO) doped polypyrrole (PPy) was encapsulated in mesoporous SBA-15. All of the synthesized samples were characterized by infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. They were investigated as humidity-sensor materials at room temperature. The sensor showed excellent humidity sensitivity in the relative humidity range 11–95%. The humidity-sensing properties were very much improved by encapsulation of the NiO-doped PPy into mesoporous silica SBA-15. Finally, the sensitivity mechanism was investigated by direct-current (dc) and alternating-current (ac) analysis. The dc circuit with the instantaneous polarity reversion method was designed by us to study the dc response in different humidity environments. The conductive mechanism was established through the dc and ac investigation, and the conductive particles were identified as ions and electrons. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Yuan He, Tong Zhang, Wei Zheng, Rui Wang, Xiangwei Liu, Yan Xia, Jinwei Zhao
Sensors and Actuators B: Chemical 2010 Volume 146(Issue 1) pp:98-102
Publication Date(Web):8 April 2010
DOI:10.1016/j.snb.2010.02.030
Barium titanate (BaTiO3) nanofiber was synthesized by electrospinning and by using the calcinations technique. Its morphologies were characterized by scanning electron microscopy, which showed that its average diameter was 80–200 nm, and its length was over 0.1 mm. An impedance-type humidity sensor was then fabricated based on this BaTiO3 nanofiber. It was unexpected to find that such sensor exhibited fast response and recovery, which were 5 and 4 s between 11% and 95% relative humidity, respectively. The long stability and humidity hysteresis properties of this sensor were also tested, and they were found to be optimum. These excellent sensing characteristics prove that BaTiO3 nanofiber is applicable for high-performance humidity sensors.
Co-reporter:Xiangwei Liu, Rui Wang, Tong Zhang, Yuan He, Jinchun Tu, Xiaotian Li
Sensors and Actuators B: Chemical 2010 Volume 150(Issue 1) pp:442-448
Publication Date(Web):21 September 2010
DOI:10.1016/j.snb.2010.05.033
An ordered mesoporous In2O3 material with crystalline walls has been synthesized through the nanocasting method. It was investigated as an impedance-type humidity sensor for the detection of water vapor. A nanostructured In2O3 matrix has been obtained by the hard template route from the KIT-6 silica template. The crystalline In2O3 belonged to the Ia3d space group, and its structure was characterized by X-ray diffraction (XRD), N2 adsorption–adsorption, and transmission electron microscopy (TEM). The sensor based on mesoporous In2O3 showed excellent performance in terms of humidity changes and favorable stability. Through the analysis of its semiconductor characteristics, Kelvin equation, and complex impedance, we found that the 3D mesoporous structure contributes greatly to the improvement of humidity-sensitive properties. A possible mechanism was established to explain the excellent performance of the mesoporous In2O3-made humidity-sensing device. The evaluation of its electrical characterization and the establishment of its sensing mechanism shows that mesoporous In2O3 is a good candidate for developing humidity sensors. It has potential applications in the chemical-sensing field.
Co-reporter:Rui Wang, Xiangwei Liu, Yuan He, Qing Yuan, Xiaotian Li, Geyu Lu, Tong Zhang
Sensors and Actuators B: Chemical 2010 Volume 145(Issue 1) pp:386-393
Publication Date(Web):4 March 2010
DOI:10.1016/j.snb.2009.12.025
MgO-SBA-15 has been successfully developed as a kind of humidity-sensitive material. The structure of MgO-SBA-15 materials was characterized by XRD, IR spectroscopy, N2 adsorption–desorption, TEM and XPS. The study proved that the MgO did not destroy the mesoporous structure of SBA-15 via the characteristic results of XRD and N2 adsorption–desorption. Researchers built the thick film humidity sensors on the Al2O3 ceramic substrate with two Ag–Pd interdigital electrodes with five fingers. The sensor shows excellent humidity sensitivity from 11% to 95%RH, and it has very good response and recovery property. The response time is about 10 s and the recovery time is about 20 s. We found that the mesoporous structure of the sensing materials contributed to the humidity sensitivity. We discussed a possible mechanism based on the humidity sensor produced by MgO-SBA-15.
Co-reporter:Yi Zeng, Tong Zhang, Haibin Yang, Liang Qiao, Qi Qi, Feng Cao, Yanyan Zhang, Rui Wang
Applied Surface Science 2009 Volume 255(Issue 7) pp:4045-4049
Publication Date(Web):15 January 2009
DOI:10.1016/j.apsusc.2008.10.079
Abstract
Cu–Zn/ZnO nanocomposites with a novel core-shell structure have been prepared by a surface precipitation process in aqueous solution. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy are employed to analyze the structure and morphology of the present products. The influence of the annealing temperature on the core-shell structure of the nanocomposites is investigated, and a possible growth model is proposed. Furthermore, the gas sensors based on the Cu–Zn/ZnO nanocomposites are fabricated and tested, which exhibits high sensitivity and fast response to CO. The best results are obtained for the sensor based on the film annealed at 350 °C, which shows that the sensitivity is about 6.3 when the sensor is exposed to 100 ppm CO at the operating temperature of 240 °C. The possible sensing mechanism of the Cu–Zn/ZnO sensing film has also been discussed.
Co-reporter:Lijie Wang, Tong Zhang, Qi Qi, Jiahuan Hu, Yi Zeng, Geyu Lu
Materials Letters 2009 Volume 63(Issue 11) pp:903-904
Publication Date(Web):30 April 2009
DOI:10.1016/j.matlet.2009.01.057
Na2Ti3O7 nanowires with diameters of about 80-130 nm and lengths up to several tens of micrometers are synthesized via a simple hydrothermal method and characterized by the field-emission scanning electron microscopy and X-ray diffraction. Back-gate field-effect transistors based on these nanowires are fabricated on indium tin oxide glass substrates with polymethyl-methacrylate-co-glyciclyl-methacrylate as the gate insulator layers. Typical p-type semiconductor material properties are observed in our investigations. The field-effect mobility is about 0.1 cm2/Vs. The capacitance per unit area of the dielectric is 3.43 nF/cm2 (dielectric constant, k = 3.9). The on/off ratio is around 103 at the conduction of 10 V.
Co-reporter:Yi Zeng, Tong Zhang, Liang Qiao
Materials Letters 2009 Volume 63(Issue 11) pp:843-846
Publication Date(Web):30 April 2009
DOI:10.1016/j.matlet.2009.01.012
Large-scale uniform nutlike ZnO microcrystals are successfully synthesized via a facile hydrothermal process at low temperature (95 °C). The structure and morphology of the ZnO products are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The results reveal that the as-prepared ZnO products have average length of 2.2 µm and diameter of 1.8 µm, possessing a single crystal wurtzite structure. The possible formation mechanism of nutlike microcrystals is proposed. The samples exhibit excellent ethanol sensing properties at the operating temperature of 250 °C detecting ethanol as low as 1 ppm.
Co-reporter:Yi Zeng, Tong Zhang, Huitao Fan, Wuyou Fu, Geyu Lu, Yongming Sui and Haibin Yang
The Journal of Physical Chemistry C 2009 Volume 113(Issue 44) pp:19000-19004
Publication Date(Web):October 12, 2009
DOI:10.1021/jp905230h
We have successfully fabricated hierarchical ZnSnO3 nanocages via a facile one-pot solution synthesis method. Field emission scanning electron microscopic and transmission electron microscopic results reveal that the cubic ZnSnO3 samples with hollow interior and porous shells are cage-like structure with the side length of 200−400 nm, where the subunits are irregular-shaped nanoparticles. The time-dependent morphology of the ZnSnO3 samples has been investigated, and a possible formation mechanism of these hierarchical structures is proposed. Moreover, gas sensor based on hierarchical ZnSnO3 nanocages exhibits better sensing properties compared with the solid ZnSnO3 nanocubes. The facile preparation method may provide an easy path to the extendable synthesis of other functional nanomaterials with hollow structure and further exploitation of the potential applications.
Co-reporter:Yi Zeng, Tong Zhang, Wuyou Fu, Qingjiang Yu, Guorui Wang, Yanyan Zhang, Yongming Sui, Lijie Wang, Changlu Shao, Yichun Liu, Haibin Yang and Guangtian Zou
The Journal of Physical Chemistry C 2009 Volume 113(Issue 19) pp:8016-8022
Publication Date(Web):2017-2-22
DOI:10.1021/jp808939n
Large-scale uniform nutlike ZnO microcrystals are successfully synthesized via a facile hydrothermal process. Field emission scanning electron microscopy and transmission electron microscopy results reveal that the as-prepared ZnO products have average lengths of 2.2 μm and diameters of 1.8 μm, possessing a wurtzite structure. The evolution process of the nutlike ZnO microcrystals has been viewed by FESEM characterization, and the results reveal that the reaction time plays a crucial role in determining the final size and shape of the samples. It is also found that the existence of triethanolamine (TEA) is vital to the formation of the complex microcrystals formed from self-assembled nanoparticles, and a possible formation mechanism is proposed. Optical properties of the ZnO sample are also investigated by PL spectroscopy. It is found that the intensity of the visible emission shows an obvious decrease after the nutlike ZnO is annealed in air for 90 min. Moreover, the UV emission is further identified to originate from the recombination of the radiative free exciton and the donor bound excition by the temperature-dependent PL spectra.
Co-reporter:Qi Qi, Tong Zhang, Shujuan Wang, Xuejun Zheng
Sensors and Actuators B: Chemical 2009 Volume 137(Issue 2) pp:649-655
Publication Date(Web):2 April 2009
DOI:10.1016/j.snb.2009.01.042
KCl-doped ZnO nanofibers are synthesized via an electrospinning method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The humidity sensing properties of these nanofibers are investigated by screen-printing them on a ceramic substrate with a pair of Ag–Pd interdigitated electrodes. The experimental results show that the 5.7 wt% KCl-doped ZnO nanofibers hold super-rapid response and recovery, high response value, good reproducibility, linearity, selectivity, and stability at 100 Hz. Especially, the response time and recovery time is only about 2 and 1 s, respectively. These results demonstrate the potential application of KCl-doped ZnO nanofibers for fabricating high performance humidity sensors.
Co-reporter:Yi Zeng, Tong Zhang, Mingxia Yuan, Minghui Kang, Geyu Lu, Rui Wang, Huitao Fan, Yuan He, Haibin Yang
Sensors and Actuators B: Chemical 2009 Volume 143(Issue 1) pp:93-98
Publication Date(Web):4 December 2009
DOI:10.1016/j.snb.2009.08.053
High preferential c-axis oriented ZnO nanorods aligned on SiO2/Si substrates with interdigital electrodes have been successfully fabricated through aqueous solution methods. The transparent ZnO buffer layer covered on both the conducting electrodes and the insulating SiO2 spacer regions acts as lattice-matched template for the assembly of c-axis oriented ZnO nanorod arrays, and the subsequent growth of ZnO nanorods has been completed via a low temperature hydrothermal process. Detailed structural characterizations reveal that the as-synthesized nanorods are single crystalline, with a hexagonal phase, and with growth along the [0 0 1] direction. The gas-sensing properties of ZnO nanorod thin films are studied. It is found that the ZnO nanorod thin film sensor exhibits excellent sensing properties towards acetone at 300 °C with the response time shorter than 5 s.
Co-reporter:Yi Zeng, Tong Zhang, Huitao Fan, Geyu Lu, Minghui Kang
Sensors and Actuators B: Chemical 2009 Volume 143(Issue 1) pp:449-453
Publication Date(Web):4 December 2009
DOI:10.1016/j.snb.2009.07.021
Hollow ZnSnO3 nanocubes with peculiar cage- and skeleton-like architectures are successfully synthesized by a simple hydrothermal process at 180 °C for 12 h. These ZnSnO3 nanostructures exhibit almost uniform cubic structures with side length of 200–400 nm. The gas sensor based on these ZnSnO3 nanostructures exhibits high response and quick response-recovery to ethanol and HCHO, which also shows superior sensitive performance compared with the results of sensor based on solid ZnSnO3 nanocubes.
Co-reporter:Yi Zeng, Tong Zhang, Lijie Wang, Minghui Kang, Huitao Fan, Rui Wang, Yuan He
Sensors and Actuators B: Chemical 2009 Volume 140(Issue 1) pp:73-78
Publication Date(Web):18 June 2009
DOI:10.1016/j.snb.2009.03.071
The large-scale flowerlike ZnO nanostructures, consisting of many aggregative nanorods with the diameter of about 60 nm, were prepared by a simple and facile hydrothermal route. The toluene sensing properties of the pure ZnO and TiO2-doped ZnO nanostructures were tested at different operating temperatures from 160 to 390 °C and toluene concentrations ranging from 1 to 3000 ppm. The results indicate that the response of the ZnO nanostructures towards toluene was enhanced significantly by TiO2 doping, which was deposited onto the ZnO products by evaporation. It is found that the TiO2-doped ZnO sensor exhibits remarkably enhanced response of 17.1 at the optimal operating temperature of 290 °C to 100 ppm toluene, which has been improved up from 7.4 at 390 °C from pure ZnO nanostructures.
Co-reporter:Tong Zhang, Li Liu, Qi Qi, Shouchun Li, Geyu Lu
Sensors and Actuators B: Chemical 2009 Volume 139(Issue 2) pp:287-291
Publication Date(Web):4 June 2009
DOI:10.1016/j.snb.2009.03.036
In/Pd-doped SnO2 is synthesized via a sol–gel method and coated on a silicon substrate with Pt electrodes to fabricate a microstructure sensor. The sensor shows high response to CO with very low cross response to common interference gases at an operating temperature of 140 °C. Especially, the sensor can detect CO down to 1 ppm (the response value is about 3), and the response time and recovery time are about 15 and 20 s, respectively. These results make our sensor a good candidate in practical CO sensors.
Co-reporter:Qi Qi, Yingliang Feng, Tong Zhang, Xuejun Zheng, Geyu Lu
Sensors and Actuators B: Chemical 2009 Volume 139(Issue 2) pp:611-617
Publication Date(Web):4 June 2009
DOI:10.1016/j.snb.2009.03.041
Pure and KCl-doped TiO2 nanofibers with different crystallographic structures are synthesized by electrospinning and calcination techniques, and their humidity sensing properties are investigated. KCl-doped TiO2 nanofibers with mixed anatase and rutile structures show the highest sensing performance. The impedance of this sample linearly decreases by more than four orders of magnitude with increasing relative humidity from 11% to 95% on a semilogarithmic scale. Both the response time and recovery time are about 3 s. Excellent selectivity, prominent stability, and good reproducibility are also observed based on this sample. The high humidity sensing performance is explained in terms of the ionic contribution of KCl doping and dissociating promotion of mixed crystallographic structure.
Co-reporter:Qi Qi, Tong Zhang, Yi Zeng, Haibin Yang
Sensors and Actuators B: Chemical 2009 Volume 137(Issue 1) pp:21-26
Publication Date(Web):28 March 2009
DOI:10.1016/j.snb.2008.12.005
Cu–Zn alloy nanoparticles in mass production are synthesized through a wire electrical explosion (WEE) method. The atoms on the surface of the as-synthesized nanoparticles are oxidized to form the Cu–Zn/CuO–ZnO nanoparticles (CZ/CZNs). The humidity sensing properties of CZ/CZNs and KCl-doped Cu–Zn/CuO–ZnO nanoparticles (KCZ/CZNs) are investigated by screen-printing them on ceramic substrates with Ag–Pd interdigitated electrodes, respectively. The measurement results show that KCZ/CZNs hold the improved humidity sensing properties with the impedance varying about four orders of magnitude in the range of 11–95% relative humidity (RH), while the impedance of CZ/CZNs changes only about two orders of magnitude. The response and recovery time of KCZ/CZNs are about 40 and 50 s, respectively. And the maximum hysteresis is around 4% RH. Our results demonstrate the potential application of KCZ/CZNs for fabricating high performance humidity sensors.
Co-reporter:Qi Qi, Tong Zhang, Li Liu, Xuejun Zheng, Geyu Lu
Sensors and Actuators B: Chemical 2009 Volume 141(Issue 1) pp:174-178
Publication Date(Web):18 August 2009
DOI:10.1016/j.snb.2009.05.039
SnO2 nanofibers with and without block copolymer P123 (EO20PO70EO20) in the precursor are synthesized via a simple electrospinning method. The Brunauer–Emmett–Teller surface areas of the nanofibers with and without P123 are 113.261 and 18.025 m2 g−1, respectively. Gas sensing properties of these two samples are investigated by exposing the corresponding sensors to NH3, C2H5OH, and CH3COCH3 at 280, 300, and 340 °C, respectively. Comparing with nanofibers without P123, the SnO2 nanofibers with P123 hold enhanced response value, higher saturated-detection-concentration, and lower minimum-detection-limit. The response is 59, 75, and 65 for nanofibers with P123 to 500 ppm NH3, C2H5OH, and CH3COCH3, respectively, and is 28, 50, and 43 for nanofibers without P123. The minimum-detection-limit is 5, 1, and 1 ppm for nanofibers with P123 to detect NH3, C2H5OH, and CH3COCH3, respectively, and is 50, 20, and 10 ppm for nanofibers without P123. The improved gas sensing properties are based on their coarse and loose morphology and higher Brunauer–Emmett–Teller surface area brought by adding P123.
Co-reporter:Rui Wang, Yuan He, Tong Zhang, Zhuyi Wang, Xuejun Zheng, Ligang Niu, Fengqing Wu
Sensors and Actuators B: Chemical 2009 Volume 136(Issue 2) pp:536-540
Publication Date(Web):2 March 2009
DOI:10.1016/j.snb.2008.12.002
Nanocrystalline LaCo0.3Fe0.7O3 was prepared by a citrate method. A resistive-type humidity sensor built on a ceramic substrate with Ag–Pd interdigitated electrodes was fabricated. The humidity sensing mechanism of the ceramic materials was assessed by analyses of DC and AC test results. Electrons and ions contributing to the conduction were confirmed by DC analysis. Electrons, H+, and K+ ions were each found to dominate at different humidity ranges for the humidity sensor based on LaCo0.3Fe0.7O3 materials. The dielectric loss property was studied in detail and the humidity sensing mechanism was discussed. The results indicated that not only proton or ion but also molecular polarization contributes to the conduction in 11–95% RH.
Co-reporter:Qi Qi, Tong Zhang, Li Liu, Xuejun Zheng
Sensors and Actuators B: Chemical 2009 Volume 137(Issue 2) pp:471-475
Publication Date(Web):2 April 2009
DOI:10.1016/j.snb.2008.11.042
A simple method for the large-scale synthesis of SnO2 nanofibers has been demonstrated through an electrospinning method. The as-synthesized fibers are characterized by scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, X-ray diffraction, and energy dispersive X-ray analysis. The sensor fabricated from these fibers exhibits high response to toluene at 350 °C with good selectivity. The response time and recovery time are about 1 and 5 s, respectively. The linear dependence of the response value on the toluene concentration is observed in the range of 10–300 ppm. The potential application of SnO2 nanofibers for fabricating high performance toluene sensors at industry level has been demonstrated.
Co-reporter:Lijie Wang, Di Li, Rui Wang, Yuan He, Qi Qi, Yue Wang, Tong Zhang
Sensors and Actuators B: Chemical 2008 Volume 133(Issue 2) pp:622-627
Publication Date(Web):12 August 2008
DOI:10.1016/j.snb.2008.03.028
Pure and LiCl-doped mesoporous silica MCM-41 with different doping concentrations (1, 2, 5, 10 and 15 wt.%) have been prepared. XRD, IR spectra and SEM characterized the materials. These different characterization results suggest that these materials have the similar mesoporous structure. A resistive-type humidity sensor was fabricated on a ceramic substrate with Ag–Pd interdigital electrodes. The humidity sensing properties of the sensors were investigated at different frequencies. The studies revealed that the LiCl-doping was beneficial for improving the humidity sensing properties of the samples. The sample with 2 wt.% LiCl dopant has the best sensing properties to humidity. Finally, a possible mechanism is suggested to explain the humidity-sensitive properties.
Co-reporter:Qi Qi, Tong Zhang, Qingjiang Yu, Rui Wang, Yi Zeng, Li Liu, Haibin Yang
Sensors and Actuators B: Chemical 2008 Volume 133(Issue 2) pp:638-643
Publication Date(Web):12 August 2008
DOI:10.1016/j.snb.2008.03.035
The humidity sensitive characteristics of a sensor fabricated from flower-like ZnO nanorods by screen-printing on a ceramic substrate with Ag–Pd interdigital electrodes have been investigated. The sensor shows high humidity sensitivity, rapid response and recovery, small hysteresis, and good stability. It is found that the impedance of the sensor decreases by about five orders of magnitude with increasing relative humidity (RH) from 11 to 95%. The response and recovery time of the sensor is about 5 and 10 s, respectively. These results indicate that the flower-like ZnO nanorods can be used in fabricating high-performance humidity sensors.
Co-reporter:Qi Qi, Tong Zhang, Xuejun Zheng, Huitao Fan, Li Liu, Rui Wang, Yi Zeng
Sensors and Actuators B: Chemical 2008 Volume 134(Issue 1) pp:36-42
Publication Date(Web):28 August 2008
DOI:10.1016/j.snb.2008.04.011
Pure and Sm2O3-doped SnO2 are prepared through a sol–gel method and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The sensor based on 6 wt% Sm2O3-doped SnO2 displays superior response at an operating temperature of 180 °C, and the response magnitude to 1000 ppm C2H2 can reach 63.8, which is 16.8 times larger than that of pure SnO2. This sensor also shows high sensitivity under various humidity conditions. These results make our product be a good candidate in fabricating C2H2 sensors.
Co-reporter:Tong Zhang, Yuan He, Rui Wang, Wangchang Geng, Lijie Wang, Ligang Niu, Xiaotian Li
Sensors and Actuators B: Chemical 2008 Volume 131(Issue 2) pp:687-691
Publication Date(Web):14 May 2008
DOI:10.1016/j.snb.2007.12.059
Polypyrrole (PPY) materials were prepared by using chemical polymerization at room temperature for 96 h. A resistive-type humidity sensor was fabricated on a ceramic substrate with Ag–Pd interdigital electrodes. The humidity-sensing mechanism of the polypyrrole materials was discussed in terms of capacitance, direct current, complex impedance and dielectric loss properties. The discussion on the sensing mechanism indicated that not only electrons or ions but also dipoles contributed to the conduction in the whole relative humidity range.
Co-reporter:Qi Qi, Tong Zhang, Li Liu, Xuejun Zheng, Qingjiang Yu, Yi Zeng, Haibin Yang
Sensors and Actuators B: Chemical 2008 Volume 134(Issue 1) pp:166-170
Publication Date(Web):28 August 2008
DOI:10.1016/j.snb.2008.04.024
Dumbbell-like ZnO microcrystals have been obtained through a facile solution method. The structure, morphology and optical properties of the as-prepared ZnO microcrystals have been characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and photoluminescence. The as-prepared ZnO microcrystals exhibit excellent sensing properties against acetone at an operating temperature of 300 °C. The response and recovery times are found to be 1.5 and 3 s, respectively. Moreover, the sensor holds the successful discrimination between acetone and ethanol, which makes our product a good candidate in fabricating highly selective sensors in practice.
Co-reporter:Li Liu, Tong Zhang, Qi Qi, Lei Zhang, Weiyou Chen, Baokun Xu
Solid-State Electronics 2007 Volume 51(Issue 7) pp:1029-1033
Publication Date(Web):July 2007
DOI:10.1016/j.sse.2007.05.016
A micro-structure ethanol gas sensor on a silicon substrate based on the nano complex oxide La0.7Sr0.3FeO3 was successfully designed and fabricated. The heater electrode and signal electrode were designed on the same plane in order to reduce the cross-talk and make the fabrication easier. The results of the simulations are used to improve the temperature distribution on the sensor. Compared to classical sintered gas sensors, the optimized design leads to a low power consumption. The experimental results show that the power consumption is approximately two thirds of the sintered gas sensors with the same active material. The sensitivity of this novel sensor is 8.0 when the concentration of ethanol is 500 ppm, and the response time is about 1.5 s and the recovery is about 2.5 s.
Co-reporter:Rui Wang, Yuan He, Tong Zhang, Zhuyi Wang, Xuejun Zheng, Ligang Niu, Fengqing Wu
Sensors and Actuators B: Chemical (2 March 2009) Volume 136(Issue 2) pp:536-540
Publication Date(Web):2 March 2009
DOI:10.1016/j.snb.2008.12.002
Nanocrystalline LaCo0.3Fe0.7O3 was prepared by a citrate method. A resistive-type humidity sensor built on a ceramic substrate with Ag–Pd interdigitated electrodes was fabricated. The humidity sensing mechanism of the ceramic materials was assessed by analyses of DC and AC test results. Electrons and ions contributing to the conduction were confirmed by DC analysis. Electrons, H+, and K+ ions were each found to dominate at different humidity ranges for the humidity sensor based on LaCo0.3Fe0.7O3 materials. The dielectric loss property was studied in detail and the humidity sensing mechanism was discussed. The results indicated that not only proton or ion but also molecular polarization contributes to the conduction in 11–95% RH.
Co-reporter:Qi Qi, Tong Zhang, Qingjiang Yu, Rui Wang, Yi Zeng, Li Liu, Haibin Yang
Sensors and Actuators B: Chemical (12 August 2008) Volume 133(Issue 2) pp:638-643
Publication Date(Web):12 August 2008
DOI:10.1016/j.snb.2008.03.035
The humidity sensitive characteristics of a sensor fabricated from flower-like ZnO nanorods by screen-printing on a ceramic substrate with Ag–Pd interdigital electrodes have been investigated. The sensor shows high humidity sensitivity, rapid response and recovery, small hysteresis, and good stability. It is found that the impedance of the sensor decreases by about five orders of magnitude with increasing relative humidity (RH) from 11 to 95%. The response and recovery time of the sensor is about 5 and 10 s, respectively. These results indicate that the flower-like ZnO nanorods can be used in fabricating high-performance humidity sensors.
Co-reporter:Lili Wang, Jianan Deng, Zheng Lou and Tong Zhang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 26) pp:NaN10028-10028
Publication Date(Web):2014/03/11
DOI:10.1039/C4TA00651H
Quasi-1D nanofibers with heterostructure were prepared via a simple two-step process called the electrospinning technique and hydrothermal process. The nanostructures exhibit the unique feature of TiO2 nanofibers (250 nm) kept inside and well-structured Co3O4 octahedral nanoparticles loading outside. The cross-linked Co3O4/TiO2 nanostructures exhibit intriguing morphologies, architectures and chemical compositions. As a potential sensing material in chemosensor applications, the quasi-1D heterostructure nanofibers exhibit a relatively high catalysis response to CO, and good CO-sensing performance even exposure to a humid environment.
Co-reporter:Jing Cao, Ziying Wang, Rui Wang, Sen Liu, Teng Fei, Lijie Wang and Tong Zhang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 10) pp:NaN5641-5641
Publication Date(Web):2015/01/27
DOI:10.1039/C4TA06892K
Different components and well-defined structures may cooperatively improve the performances of composite materials and enhance their applicability. In this paper, core–shell α-Fe2O3@NiO nanofibers (α-Fe2O3@NiO CSNFs) with hollow nanostructures are synthesized by a facile coaxial electrospinning method and calcination procedure. Considering the temperature-dependent solute degradation process and different influencing factors including the solvent evaporation rate and phase separation, a multistage formation mechanism has been proposed to understand the formation of the CSNF structure. The gas sensing tests indicate that the α-Fe2O3@NiO CSNFs exhibit significantly improved gas sensitivity and selectivity performances in comparison with NiO hollow nanofibers (NiO HNFs) and α-Fe2O3 nanofibers (α-Fe2O3 NFs). The response of α-Fe2O3@NiO CSNFs to 50 ppm HCHO at 240 °C is ∼12.8, which is 10- and 7.1-times higher than those of pure NiO and α-Fe2O3, respectively. The synergy between the heterojunction, core–shell hollow nanofiber structure and Fe loading into the NiO shell contribute to the enhanced response of α-Fe2O3@NiO CSNFs. Moreover, extremely fast response–recovery behavior (∼2 s and ∼9 s) has been observed at the optimal working temperature of 240 °C. The detection limit for HCHO could be lower than 1 ppm. These favorable gas sensing performances make the α-Fe2O3@NiO CSNFs promising materials for gas sensors.
Co-reporter:Lijie Wang, Jiahuan Hu, Hongyu Zhang and Tong Zhang
Chemical Communications 2011 - vol. 47(Issue 24) pp:NaN6839-6839
Publication Date(Web):2011/05/10
DOI:10.1039/C1CC10882D
FETs based on Au-impregnated polyacrylonitrile (PAN)/polythiophene (PTH) core–shell nanofibers have been fabricated and exhibit high mobility (∼2.0 cm2 V−1 s−1).
Co-reporter:Lili Wang, Zheng Lou, Rui Wang, Teng Fei and Tong Zhang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 25) pp:NaN12456-12456
Publication Date(Web):2012/05/09
DOI:10.1039/C2JM16509K
A new type of ring-like architecture with a lamellar structure was prepared via a simple hydrothermal strategy in the case of PdO–NiO, which showed a low operating temperature, a high response and rapid response/recovery to CO gas.
Co-reporter:Lili Wang, Zheng Lou, Teng Fei and Tong Zhang
Journal of Materials Chemistry A 2011 - vol. 21(Issue 48) pp:NaN19336-19336
Publication Date(Web):2011/10/28
DOI:10.1039/C1JM13354C
A new type of spherically multilayered core–shell structure was prepared via a simple hard template strategy in the case of ZnO. The structure and morphology characteristics of the resultant product were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The ZnO microspheres with hollow interior and porous shells are multilayered structures with diameters ranging from 0.4 to 3.5 μm. Further investigation of the formation mechanism reveals that the preheating program is vital to the formation of the multishelled structures. To demonstrate the usage of such a multilayered nanomaterial, a chemical gas sensor has been fabricated and investigated for toluene detection. The sensor exhibits excellent sensing performances in terms of high response, low detection limit, rapid response-recovery, and superior selectivity.
Co-reporter:Lili Wang, Teng Fei, Jianan Deng, Zheng Lou, Rui Wang and Tong Zhang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 35) pp:NaN18114-18114
Publication Date(Web):2012/06/22
DOI:10.1039/C2JM32520A
A new type of rattle-type structure with a porous shell was prepared via a simple template strategy in the case of SnO2, which showed high response and good selectivity to ethanol.
Co-reporter:Lili Wang, Zheng Lou, Teng Fei and Tong Zhang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 11) pp:NaN4771-4771
Publication Date(Web):2012/01/30
DOI:10.1039/C2JM15342D
Au-loaded ZnO hollow nanospheres have been successfully synthesized by using carbon nanospheres as sacrificial templates. This simple strategy could be expected to be extended for the fabrication of similar metal–oxide loaded hollow nanospheres using different precursors. The structural and morphological characteristics of the resultant product were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The hollow nanospheres are porous, with the diameters ranging from 220 to 280 nm. To demonstrate the usage of such Au-loaded ZnO nanomaterial, a chemical gas sensor has been fabricated and investigated for NH3 detection. The Au-loaded ZnO sensor exhibits excellent sensing performances compared with hollow ZnO and compact ZnO sensors. The dynamic transients of the Au-loaded ZnO sensors demonstrated both their fast response (0.8–1.5 s) and recovery (3–4 s) towards NH3 gases. The combination of ZnO hollow structure and catalytic activity of Au loaded gives a very attractive sensing behavior for applications as real-time monitoring gas sensors with fast responding and recovering speed.
Co-reporter:Sen Liu, Bo Yu and Tong Zhang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 42) pp:NaN13320-13320
Publication Date(Web):2013/08/23
DOI:10.1039/C3TA12594G
In this work, reduced graphene oxide–poly(p-phenylenediamine) (rGO–PpPD) hybrids have been successfully prepared through a facile and effective method by heat treatment of GO aqueous dispersion in the presence of pPD at 80 °C for 2 h. The combined characterization by scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) indicates the successful production of rGO–PpPD hybrids with a crumpled morphology. The formation of rGO–PpPD hybrids is attributed to the redox reactions between GO and pPD, where the reduction of GO to rGO and polymerization of pPD into PpPD occurred simultaneously. It was found that rGO–PpPD hybrids show good catalytic activity toward oxidation of dopamine (DA), and no response to ascorbic acid (AA) and uric acid (UA), leading to a high-performance DA sensor. The linear detection ranges are estimated to be from 5 μM to 25 μM (r = 0.998) and 50 μM to 200 μM (r = 0.995), respectively. The detection limit is estimated to be 0.36 μM at a signal-to-noise ratio of 3.
Co-reporter:Jianan Deng, Lili Wang, Zheng Lou and Tong Zhang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 24) pp:NaN9034-9034
Publication Date(Web):2014/03/11
DOI:10.1039/C4TA00160E
A new type of quasi-1D nanofiber architecture with a heterostructure was prepared via a combination of electrospinning and hydrothermal strategies in the case of CuO–TiO2, which required a low operating temperature, and showed a high response and excellent selectivity to formaldehyde and ethanol gases.
