Co-reporter:Zhongqian Song;Yingying Fan;Zhonghui Sun;Dongxue Han;Yu Bao
Journal of Materials Chemistry A 2017 vol. 5(Issue 39) pp:20797-20807
Publication Date(Web):2017/10/10
DOI:10.1039/C7TA06040H
Integration of the contradictory attributes of a well-aligned pore structure and excellent electrical/mechanical properties into graphene-based macroscopic materials perfectly for wearable and portable electronics and energy devices is still a big challenge hitherto. In this study, a simple yet highly efficient reduction and evaporation co-induced self-assembly (RES) method was successfully developed to prepare self-crosslinking Janus graphene films with well-aligned pore and dense shell structures, which endowed the material with excellent electrical conductivity and good mechanical property. Electrochemical studies demonstrate that the graphene films with a thickness of 12.4 μm exhibit an extraordinary volumetric capacitance of 127.7 F cm−3 at a current density of 0.5 mA cm−2, which is superior to that reported in most of the previous studies. The flexible all-solid state supercapacitor based on the Janus graphene films exhibits an ultrahigh energy density of 2.78 mW h cm−3 at 40.3 mW cm−3 as well as a remarkable cycling performance (95.5% of initial capacitance is retained after 10 000 cycles at 2 mA cm−2). The fatigue tests further confirm the preferable flexibility and bending and folding capability of the proposed supercapacitor; these are crucial factors to be considered for further wearable applications. These tough and durable supercapacitor devices connected in series have been successfully well-designed into wearable energy storage systems to power small gadgets such as electronic watches and light-emitting diodes. In addition, the microgels formed during the film preparation process are helpful as microgel films can be engraved into micro-supercapacitor patterns that can work as an integrated photodetection system. This strategy can be potentially applied for the design and fabrication of new flexible and portable graphene-based wearable electronic devices.
Co-reporter:Tongshun Wu, Luyi Zou, Dongxue Han, Fenghua Li, Qixian Zhang and Li Niu
Green Chemistry 2014 vol. 16(Issue 4) pp:2142-2146
Publication Date(Web):08 Jan 2014
DOI:10.1039/C3GC42454E
Novel photocatalysts consisting of porphyrin and graphene have been designed to reduce CO2 to hydrocarbons under visible light. These catalysts can (i) effectively reduce CO2 to hydrocarbons, particularly to C2H2; and (ii) selectively control the transfer of photogenerated electrons from graphene to CO2 rather than to H2O.
Co-reporter:Yuanjian Zhang, Keisuke Fugane, Toshiyuki Mori, Li Niu and Jinhua Ye
Journal of Materials Chemistry A 2012 vol. 22(Issue 14) pp:6575-6580
Publication Date(Web):15 Feb 2012
DOI:10.1039/C2JM00044J
The oxygen reduction reaction (ORR) is one of the important reactions not only in life processes but also in artificial energy conversion systems, such as fuel cells and metal/air batteries. As one of the non-precious ORR catalysts, N-doped carbon materials show an exciting activity, but most of them were universally synthesized by high-temperature pyrolysis or annealing up to 1100 °C in the past few decades, which makes the structural manipulation of the catalysts extremely difficult. Here, we propose that ORR active N-doped carbon catalysts could, in principle, be prepared via a sophisticated wet chemical reaction between a reactive graphitic carbon template (e.g. graphene oxide) and N-containing molecules (e.g. dicyandiamide) at temperatures as low as 180 °C. Without any high-temperature treatments, for example, the as-prepared N-doped reduced graphene oxide with additional Fe-containing nanoparticles showed an impressive ORR catalytic activity that was comparable to many previous N-doped carbon from high-temperature pyrolysis. Rational utilization of the graphitic carbon template, the N-containing molecules, and the wet chemical reactions may offer a low-temperature route to create interesting ORR electrocatalysts with easier surface properties manipulation.
Co-reporter:Min Zhou, Shiyu Gan, Bin Cai, Fenghua Li, Weiguang Ma, Dongxue Han, and Li Niu
Analytical Chemistry 2012 Volume 84(Issue 7) pp:3480-3483
Publication Date(Web):March 12, 2012
DOI:10.1021/ac300473a
We report on a novel material, tetrakis(4-chlorophenyl)borate (TB–) anion doped nanocluster films, as the solid contact (SC) for producing well-defined, electrochemically reversible, and nonpolarizable double interfaces on it. Detailed studies have unambiguously revealed that, for the first time, the developed SC can fully overcome all the signal stability problems of ion-selective electrodes (ISEs), offering a reliable and universal platform for the development of high quality SC-ISEs. As an exemplification, the developed monolayer-protected cluster (MPC) based K+-ISEs have advantages of excellent analytical performances, e.g., the low potential drift (10.1 ± 0.3 μV h–1 over 72 h measured in 0.1 M KCl and 10.8 ± 0.5 μV h–1 over 96 h rechecked in 0.1 M KCl after 1 month) and the stable and reproducible linear range, sensitivity, and standard potential (few changes within the first 6 weeks). This evidence suggests that the developed MPC films are the most promising SC transducers among all the reported ones to the best of our knowledge.
Co-reporter:Na Li, Zhongjie Li, Junhua Yuan, Jianguo Hu, Jigen Miao, Qixian Zhang, Li Niu, Jixia Song
Electrochimica Acta 2012 Volume 72() pp:150-156
Publication Date(Web):30 June 2012
DOI:10.1016/j.electacta.2012.04.026
NiHCFs nanoparticles are deposited onto the surface of multiwalled carbon nanotubes (MWCNTs) with a grafted poly(4-vinylpyridine). The as-prepared NiHCF/PV4P-g-MWCNTs composites are characterized by transition electron microscope (TEM) and Fourier transform infrared spectroscopy (FTIR), which confirms the presence of NiHCFs nanoparticles, and shows that NiHCFs nanoparticles are highly dispersed on the surface of MWCNTs in high density. Cyclic voltammograms (CVs) exhibit a great enhancement for NiHCFs/PV4P-g-MWCNTs composites in capacity and stability as ion exchanger by comparison with bulk NiHCF. The capacity for the electrodes modified with NiHCFs/PV4P-g-MWCNTs composites is 69.24 mC/cm−2 mg, after 100 cycles potential sweeping, these composites modified electrode retains its 98.5% ion-exchange capacity. These composites also exhibit a higher selectivity of for Cs+ over Na+ ions in high concentration of Na+ ion, which is confirmed by X-ray photoelectron spectroscopy (XPS).
Co-reporter:Fenghua Li, Junjin Ye, Min Zhou, Shiyu Gan, Qixian Zhang, Dongxue Han and Li Niu
Analyst 2012 vol. 137(Issue 3) pp:618-623
Publication Date(Web):05 Dec 2011
DOI:10.1039/C1AN15705A
Graphene sheets are used for the first time to fabricate a new type of solid-contact ion-selective electrode (SC-ISE) as the intermediate layer between an ionophore-doped solvent polymeric membrane and a glassy carbon electrode. The new transducing layer was characterized by transmission electron microscopy, scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The performance of the new K+−selective electrodes was examined by a potentiometric water layer test, potentiometric measurements, and current reversal chronopotentiometry. The obtained potentiometric sensors were characterized with a calibration line of slope close to Nernstian (59.2 mV/decade) within the activity from 10−4.5 to 0.1 M. The high capacitance of the graphene solid contacts results in a signal that is stable over one week. The short response time is less than 10 s for activities higher than 10−5 M. The potential drift of the electrodes was calculated from the slope of the curves at longer times (ΔE/Δt = 1.2 × 10−5 V s−1 (I = 1 nA) and ΔE/Δt = 5.5 × 10−5 V s−1 (I = 5 nA)). All the results indicate that graphene is a promising material for use as a transducer layer for SC-ISEs.
Co-reporter:Na Li, Bo He, Shaoya Xu, Junhua Yuan, Jigen Miao, Li Niu, Jixia Song
Materials Chemistry and Physics 2012 Volume 133(2–3) pp:726-734
Publication Date(Web):16 April 2012
DOI:10.1016/j.matchemphys.2012.01.074
Poly(4-vinylpyridine) (P4VB) was grafted to multiwalled carbon nanotubes (MWCNTs) by an in situ polymerization. This grafted polymer plays two roles in the synthesis of Prussian Blue (PB)/MWCNT composites: (1) a stabilizer to protect PB nanoparticles from aggregation; (2) a linker to anchor these nanoparticles on the surface of MWCNTs. The size of PB nanoparticles deposited on MWCNTs can be controlled by in site layer-by-layer coordination of Fe3+ and [Fe(CN)6]4− ions in aqueous solution. The as-prepared PB/P4VP-g-MWCNT composites were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray powder diffraction, which revealed that these PB nanoparticles were uniformly distributed on the surface of MWCNTs, and grew upon layer-by-layer assembly. A potential use of PB/P4VP-g-MWCNT composites was demonstrated as an electrocatalyst used in the electrochemical detection of l-cysteine. The as-prepared electrodes modified with PB/P4VP-g-MWCNT composites showed two reversible redox waves assigned to a fast surface-controlled processes. The analytical performance for l-cysteine detection is associated with the load of PB nanoparticles onto MWCNTs. In an optimal experiment, for these as-prepared electrodes, their detection limit of l-cysteine can be measured as low as 0.01 μM with a sensitivity 778.34 nA μM−1 cm−2.Highlights► Carbon nanotubes were grafted with poly(4-vinylpyridine). ► Prussian blue nanoparticles were deposited on carbon nanotubes by complextion. ► The size of these nanoparticles can be controlled by layer-by-layer assembly. ► The compoistes show a superior catalytic activity to the oxidation of L-cysteine. ► The efficiency is dependent on the capacity of Prussian blue nanoparticles loaded.
Co-reporter:Yuwei Hu, Kaikai Wang, Qixian Zhang, Fenghua Li, Tongshun Wu, Li Niu
Biomaterials 2012 33(4) pp: 1097-1106
Publication Date(Web):
DOI:10.1016/j.biomaterials.2011.10.045
Co-reporter:Yuwei Hu, Dongxue Han, Qixian Zhang, Tongshun Wu, Fenghua Li, Li Niu
Biosensors and Bioelectronics 2012 Volume 38(Issue 1) pp:396-401
Publication Date(Web):October–December 2012
DOI:10.1016/j.bios.2012.06.042
A perylene ligand, N,N-bis-(1-aminopropyl-3-propylimidazol salt)-3,4,9,10-perylene tetracarboxylic acid diimide ligand (PDI), which consisted of π-conjugated perylene moiety and hydrophilic side chains with positively charged imidazole rings, was used to wrap G-quadruplex for fluorescence turn-on K+ recognition. Electrostatic attraction between PDI's positively charged imidazole rings and DNA's negatively charged phosphate backbones enabled PDI to accumulate on DNA. Upon trapping K+, these G-rich DNA sequences transitioned to G-quadruplex. Subsequently, PDI ligands wrapped G-quadruplex, in which the flat aromatic core of PDI ligand interacted with G-quartet through π–π stacking and the side chains were positioned in grooves through electrostatic interactions. Consequently, the interaction mode change and conformational transition from PDI stacked G-sequence to PDI wrapped G-quadruplex led to PDI fluorescence enhancement, which was readily monitored as the detection signal. This strategy excluded the sequence tagging step and exhibited high selectivity and sensitivity towards K+ ion with the linear detection range of 10–150 nM. Besides, PDI ligands may hold diagnostic and therapeutic application potentials to human telomere and cancer cells.Highlights► Upon trapping K+, G-rich DNA sequences transitioned to G-quadruplex. ► Conformation changed from PDI stacked G-sequence to PDI wrapped G-quadruplex. ► Fluorescence enhancement of PDI was observed. ► Fluorescent K+ recognition with high sensitivity and selectivity was achieved.
Co-reporter:Yan Mao, Yu Bao, Dongxue Han, Fenghua Li, Li Niu
Biosensors and Bioelectronics 2012 Volume 38(Issue 1) pp:55-60
Publication Date(Web):October–December 2012
DOI:10.1016/j.bios.2012.04.043
A new type of eco-friendly molecularly imprinted polymer (MIP) was synthesized through an efficient one-pot room-temperature sol–gel polymerization and applied as a molecular recognition element to construct dopamine (DA) fluorescence (FL) optosensor. Highly luminescent carbon dots (CDs) were firstly synthesized via a one-step reaction in organosilane, and their surface were anchored with MIP matrix (CDs@MIP). The resulting composite of a synergetic combination of CDs with MIP showed high photostability and template selectivity. Moreover, the composite allowed a highly sensitive determination of DA via FL intensity decreasing when removal of the original templates. The new MIP-based DA sensing protocol was applied to detect DA concentration in aqueous solution, the relative FL intensity of CDs@MIP decreased linearly with the increasing DA in the concentration range of 25–500 nM with a detection limit (3σ) of 1.7 nM. Furthermore, the proposed method was successfully intended for the determination of trace DA in human urine samples without the interference of other molecules and ions.Highlights► An eco-friendly CDs@MIP composite was synthesized. ► The synthesis process was a one-pot room-temperature sol–gel polymerization. ► CDs@MIP was the molecular recognition element of fluorescence optosensor. ► The optosensor exhibited high sensitive and selective towards dopamine.
Co-reporter:Jia Chai, Fenghua Li, Yuwei Hu, Qixian Zhang, Dongxue Han and Li Niu
Journal of Materials Chemistry A 2011 vol. 21(Issue 44) pp:17922-17929
Publication Date(Web):12 Oct 2011
DOI:10.1039/C1JM13631C
A novel hollow AuPd (hAuPd) alloy nanostructure with a rough surface was fabricated via a facile one-pot simultaneous reduction of Au(III) and Pd(I) and then assembled on ionic liquid-grafted graphene sheets by electrostatic interaction to form graphene–metal hybrid nanomaterials under mild conditions. The resulting hollow alloy nanostructure and graphene nanocomposites were then characterized using many techniques, such as transmission electron microscopy (TEM), high-resolution TEM (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), element analysis mapping, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), confirming that the alloy nanoparticles with hollow cores had been successfully synthesized by one step galvanic replacement and attached firmly onto the graphene sheets. The electrocatalytic ability of the resulting nanocomposites for direct oxidation of formic acid was also explored. The hollow AuPd alloy nanospheres, especially the graphene-supported nanocomposites, exhibited striking electrocatalytic activities which show potential application in fuel cells.
Co-reporter:Di Wei, Piers Andrew, Huafeng Yang, Yuanyuan Jiang, Fenghua Li, Changsheng Shan, Weidong Ruan, Dongxue Han, Li Niu, Chris Bower, Tapani Ryhänen, Markku Rouvala, Gehan A. J. Amaratunga and Ari Ivaska
Journal of Materials Chemistry A 2011 vol. 21(Issue 26) pp:9762-9767
Publication Date(Web):03 Jun 2011
DOI:10.1039/C1JM10826C
Different formulations of solution-processable graphene have been characterised as electrode materials for use in electrochemical energy storage devices. Graphene was fabricated by chemical reduction of exfoliated graphene oxide (GO), and modified with either p-type (e.g. polyaniline) or n-type anionic groups (poly(styrenesulfonate) (PSS−) and poly[2,5-bis(3-sulfonatopropoxy)-1,4-ethynylphenylene-alt-1,4-ethynylphenylene] sodium salt (PPE-SO3−) anion). Solutions of these graphene compounds were deposited on charge collecting electrodes and used as battery cathodes. Electrodes using the anionically-modified graphene inks containing anatase titanate (TiO2) nanoparticles show improved performance over pristine graphene ink as well as the p-type conducting polymer modified ones. In addition, the open circuit voltage of batteries based on TiO2 has been boosted over 3 V with good cyclability when mixed with the graphene ink. Combined with a polymer electrolyte, this work suggests a feasible route towards fully printable rechargeable lithium batteries based on graphene inks. This approach is both versatile and scalable and is adaptable to a wide variety of applications.
Co-reporter:Yuwei Hu, Fenghua Li, Xiaoxue Bai, Dan Li, Shucheng Hua, Kaikai Wang and Li Niu
Chemical Communications 2011 vol. 47(Issue 6) pp:1743-1745
Publication Date(Web):01 Dec 2010
DOI:10.1039/C0CC04514D
Negative-charge change and conformation transition upon DNA immobilization and hybridization on functionalized graphene sheets were monitored by the EIS technique and adopted as the signal for label-free electrochemical DNA hybridization detection.
Co-reporter:Junhua Yuan, Xiaoli Jin, Na Li, Jianrong Chen, Jigen Miao, Qixian Zhang, Li Niu, Jixia Song
Electrochimica Acta 2011 Volume 56(Issue 27) pp:10069-10076
Publication Date(Web):30 November 2011
DOI:10.1016/j.electacta.2011.08.093
Multiwalled carbon nanotubes (MWCNTs) were grafted with poly(4-vinylpyridine) (PV4P) in aqueous solution by in situ free radical polymerization of 4-vinylpyridine. The as-prepared PV4P-g-MWCNTs hybrids can load phosphotungstic acid (PW) on a large scale by electrostatic interaction, which was characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The as-prepared PWs/PV4P-g-MWCNTs hybrids were modified onto a carbon glassy electrode. Cyclic voltammograms (CVs) show that the electrochemical behavior of the modified electrode follows a four-one-electron surface-confined process of Keggin-type PWs. The modified electrode can be used as a nitrite sensor. The comparison of CVs shows that the response current of nitrite reduction at the electrode modified with PWs/PV4P-g-MWCNTs hybrids is 15 times higher than that of PWs/MWCNTs hybrids in a control experiment at 0.65 V (vs. AgCl). The amperometric i–t curve for the electrode modified with PWs/PV4P-g-MWCNTs hybrids exhibits a linear concentration of NO2− ranged from 1.2 to 17.5 μM with a detection limit of 0.2 μM.Highlights► Carbon nanotubes was grafted with poly(4-vinylpyridine). ► Phosphotungstic acid was deposited onto carbon nanotubes with this polymer linker. ► This deposition is highly uniform and large scale. ► These phosphotungstic acid/carbon nanotubes hybrids can be used as nitrite sensor. ► Its linear concentration is 1.2 to 17.5 μM with a detection limit of 0.2 μM.
Co-reporter:Lijie Zhong, Min Zhou, Shiyu Gan, Yu Bao, Xiandui Dong, Li Niu, Liping Guo
Electrochemistry Communications 2011 Volume 13(Issue 3) pp:221-224
Publication Date(Web):March 2011
DOI:10.1016/j.elecom.2010.12.017
Here we propose a new and facile route based on a water-droplet modified approach to explore the voltammetric processes for a series of typical heavy metal ions at the water|1,2-dicholorethane (W|DCE) interface. This convenient method having a selective transfer characteristic indicates that a higher concentration of target ion setting can avoid the masking transfers from other interferential species. The determined Gibbs transfer energies follow an order, Pb2+ < Cd2+ < Mn2+ < Zn2+ < Co2+, Cu2+ < Ni2+, that is consistent with the ionic radius dependence on the Gibbs transfer energies described by the Born solvation model. This powerful methodology thus makes it attractive as a general strategy to probe into the direct transfer of various highly hydrophilic ions.
Co-reporter:Min Zhou, Shiyu Gan, Lijie Zhong, Xiandui Dong and Li Niu
Physical Chemistry Chemical Physics 2011 vol. 13(Issue 7) pp:2774-2779
Publication Date(Web):13 Dec 2010
DOI:10.1039/C0CP01692F
We present a more general expression for the relationship of potential dependence, which implies that a change in the interfacial drop across the interface has little effect on the free energy of the reaction, but mainly affects the surface concentration of reactant in each phase. Abundant experimental results from several well-known groups are analyzed in great detail to confirm our conclusion. At the same time, we define a new parameter named Frumkin correction factor to describe this relationship of potential dependence, which expresses the thermodynamic effect of double diffuse layers within both phases in contrast with the so often suggested kinetic electron-transfer (ET) coefficient; we also find that it depends on two intimately related aspects: the charges of reactive species and the ratio of the diffuse layer potential to the total potential within each phase, so it is quite arbitrary to ignore the diffuse layer effect in the aqueous phase just because of its relatively small values. In addition, a fascinating question on the inverted region at liquid/liquid interfaces has been successfully interpreted by an opposite surface concentration effect, which was often considered as a kinetic Marcus inverse by most groups.
Co-reporter:Junhua Yuan, Jianrong Chen, Xiaohua Wu, Keming Fang, Li Niu
Journal of Electroanalytical Chemistry 2011 Volume 656(1–2) pp:120-124
Publication Date(Web):15 June 2011
DOI:10.1016/j.jelechem.2010.12.018
The fabrication and notably improved performance of composite electrodes based on the nanocomposite of diphenylalanine peptide-covered multiwalled carbon nanotube (PP–MWCNT) is described. The synthesis of the nanocomposite of PP–MWCNT is a self-assembly process of diphenylalanine peptide (PP) along carbon nanotube (MWCNT) via aromatic stacking interaction combined with hydrogen bond of diphenylalanine peptide. PP–MWCNT modified electrode was fabricated by a simple casting method, and studied with cyclic voltammetry (CV) and chronoamperometry. PP–MWCNT modified electrode showed a high, direct and unmediated response to β-reduced coenzyme nicotinamide adenine dinucleotide (NADH) at a potential of 0.600 V (vs. SCE), which had reduced the overvoltage of NADH oxidation by 0.200 V in comparison with the bare electrode. Furthermore, the current response of NADH at PP–MWCNT modified electrode is about five times higher than that of the bare electrode. Thus, PP–MWCNT provides a new candidate for fabrication of biosensor based on β-coenzyme nicotinamide adenine dinucleotide (NAD+)-dependent dehydrogenases. Herein, an ethanol biosensor was prepared by crosslinking ethanol dehydrogenase (ADH), bovine serum albumin (BSA) and PP–MWCNT onto the electrode. The ethanol biosensor exhibited a good linearity ranged from 30 μM to 700 μM with a high sensitivity of 30.00 nA/μM cm−2 and with a low detection limit of 12 μM.Research highlights► An electrochemical active nanocomposite of diphenylalane dipeptide/multiwalled carbon nanotubes has been prepared on the basis of noncovalent assembly. ► The as-prepared nanocomposite can offer a remarkable decrease of the overvoltage of NADH oxidation, which makes it available in a high-sensitive ethanol biosensor.
Co-reporter:Yuwei Hu, Shucheng Hua, Fenghua Li, Yuanyuan Jiang, Xiaoxue Bai, Dan Li, Li Niu
Biosensors and Bioelectronics 2011 Volume 26(Issue 11) pp:4355-4361
Publication Date(Web):15 July 2011
DOI:10.1016/j.bios.2011.04.037
Sensitive electrochemical impedance assay of DNA hybridization by using a novel graphene sheets platform was achieved. The graphene sheets were firstly functionalized with 3,4,9,10-perylene tetracarboxylic acid (PTCA). PTCA molecules separated graphene sheets efficiently and introduced more negatively-charged –COOH sites, both of which were beneficial to the decoration of graphene with gold nanoparticles. Then amine-terminated ionic liquid (NH2-IL) was applied to the reduction of HAuCl4 to gold nanoparticles. The green-synthesized gold nanoparticles, with the mean diameter of 3 nm, dispersed uniformly on graphene sheets and its outer layer was positively charged imidazole termini. Due to the presence of large graphene sheets and NH2-IL protected gold nanoparticles, DNA probes could be immobilized via electrostatic interaction and adsorption effect. Electrochemical impedance value increased after DNA probes immobilization and hybridization, which was adopted as the signal for label-free DNA hybridization detection. Unlike previously anchoring DNA to gold nanoparticles, this label-free method was simple and noninvasive. The conserved sequence of the pol gene of human immunodeficiency virus 1 was satisfactorily detected via this strategy.
Co-reporter:Yan Mao, Yu Bao, Wei Wang, Zhenggang Li, Fenghua Li, Li Niu
Talanta 2011 Volume 85(Issue 4) pp:2106-2112
Publication Date(Web):30 September 2011
DOI:10.1016/j.talanta.2011.07.056
A new type of chemically converted graphene sheets, cationic polyelectrolyte-functionalized ionic liquid decorated graphene sheets (PFIL–GS) composite, was synthesized and characterized by Ultraviolet–visible (UV–vis) absorption, Fourier transform infrared, and Raman spectroscopy. It was found that the presence of PFIL enabled the formation of a very stable aqueous dispersion due to the electrostatic repulsion between PFIL modified graphene sheets. With respect to the excellent dispersibility of this material, we have fabricated a novel PFIL–GS/Prussian blue (PB) nanocomposite multilayer film via classic layer-by-layer (LBL) assembly. The assembly process was confirmed by UV–vis spectroscopy and surface plasmon resonance (SPR) spectroscopy, which showed linear responses to the numbers of the deposited PFIL–GS/PB bilayers. Moreover, the as-prepared composite films were used to detect hydrogen peroxide (H2O2) by electrochemical surface plasmon resonance (EC-SPR) spectroscopy. This real time EC-SPR technique can provide simultaneous monitoring of both optical SPR signal and electrochemical current responses upon injecting H2O2 into the reaction cell. The experimental results revealed that both the electrochemical and SPR signal exhibited splendid linear relationship to the concentration of the injected H2O2, and the detection limit could be up to 1 μM.
Co-reporter:Yuanyuan Jiang, Xindong Zhang, Changsheng Shan, Shucheng Hua, Qixian Zhang, Xiaoxue Bai, Li Dan, Li Niu
Talanta 2011 Volume 85(Issue 1) pp:76-81
Publication Date(Web):15 July 2011
DOI:10.1016/j.talanta.2011.03.028
Prussian blue (PB) was grown compactly on graphene matrix by electrochemical deposition. The as-prepared PB-graphene modified glassy carbon electrode (PB-graphene/GCE) showed excellent electrocatalytic activity towards both the reduction of hydrogen peroxide and the oxidation of hydrazine, which could be attributed to the remarkable synergistic effect of graphene and PB. The PB-graphene/GCE showed sensitive response to H2O2 with a wide linear range of 10–1440 μM at 0.0 V, and to hydrazine with a wide linear range of 10–3000 μM at 0.35 V. The detection limit was 3 μM and 7 μM, respectively, and both of them had rapid response within 5 s to reach 95% steady state response. The wide linear range, good selectivity and long-time stability of the PB-graphene/GCE make it possible for the practical amperometric detection of hydrogen peroxide and hydrazine.
Co-reporter:Min Zhou, Shiyu Gan, Lijie Zhong, Bin Su, and Li Niu
Analytical Chemistry 2010 Volume 82(Issue 18) pp:7857
Publication Date(Web):August 26, 2010
DOI:10.1021/ac102010b
Cyclic voltammetry and square wave voltammetry have been used to investigate the transfer of highly hydrophilic ions, including anions and cations, by a simple two polarized interfaces setup. The expression of apparent half-wave potential has been established detailedly by virtue of theory of sampled-current voltammetry involving semi-infinite linear diffusion, which indicates that the property of coupled ion transfer reaction has an effect on the position of the voltammogram on the potential scale. Since the data obtained agree well with literature values, it seems convincing to determine the transfer energies of those highly hydrophlic ions which are very important and have not been reported yet. Then it has been demonstrated as a novel way in combination with sensitive and fast square wave voltammetry for determining the transfer Gibbs energy of complex ions such as miscellaneous inorganic ions.
Co-reporter:Weidong Ruan, Zhicheng Lu, Tieli Zhou, Bing Zhao and Li Niu
Analytical Methods 2010 vol. 2(Issue 6) pp:684-687
Publication Date(Web):09 Apr 2010
DOI:10.1039/C0AY00068J
A facile and powerful method to form micropatterns, based on nanosphere lithography and layer-by-layer self-assembly, is described in this paper. A monolayer of hexagon close-packed polystyrene (PS) spheres (av 600 nm) was employed as the template. A positively charged polyelectrolyte of poly(diallydimethylammonium) chloride was used as adhesive to absorb oppositely charged spherical Au (av 17 nm) and spherical Ag (av 12 nm), respectively. Both the PS and substrates were coated by colloidal nanoparticles. After removal of the PS template, a micropatterning surface was obtained. Scanning electron microscopy and atomic force microscopy were used to characterize the morphologies. These resulting patterns can be used as good surface-enhanced Raman scattering (SERS) substrates. The enhancement factor is calculated to be 104 ∼ 105. This is a simple and facile technique for surface modification of metal micropatterns with SERS analytical application.
Co-reporter:Fenghua Li, Yu Bao, Jia Chai, Qixian Zhang, Dongxue Han and Li Niu
Langmuir 2010 Volume 26(Issue 14) pp:12314-12320
Publication Date(Web):June 10, 2010
DOI:10.1021/la101534n
A widely soluble graphene sheet/Congo red (GSCR) composite was synthesized and applied to prepare GSCR/Au hybrid materials. UV−vis absorption, Fourier transform infrared, Raman, and X-ray photoelectron spectra revealed that Congo red (CR) is successfully coupled on graphene sheets. The morphology of GSCR was studied by transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. The dispersion behavior of the GSCR composite was also studied in 18 different solvents, and the digital images indicate that it is soluble both in water and in a variety of organic solvents. The GSCR nanosheets are still single layers or bilayers in water and individual from one to another after 100 days of storage. Furthermore, the mechanism of GSCR’s good solubility was successfully explained by the Hansen solubility parameters. The four standard probe result shows that the GSCR films have a bulk conductivity of ∼6850 S m−1. The wide solubility and long lifetime of GSCR solutions are absolutely necessary for further treatment. As an example, Au nanoparticles densely decorated CR-functionalized graphene sheets through electrostatic interaction.
Co-reporter:Huafeng Yang, Qixian Zhang, Changsheng Shan, Fenghua Li, Dongxue Han and Li Niu
Langmuir 2010 Volume 26(Issue 9) pp:6708-6712
Publication Date(Web):March 15, 2010
DOI:10.1021/la100365z
Supramolecularly functionalized graphene-based materials with conjugated poly(2,5-bis (3-sulfonatopropoxy)-1,4-ethynylphenylene-alt-1,4-ethynylphenylene) polyelectrolyte were successfully obtained and exhibited high conductivity and stability (even for 8 months without any aid of free polymer in solution). The excellent aqueous solubility and the possibility for self-assembly through electrostatic interactions (i.e., layer-by-layer assembly) will be realized through various applications of graphene. In addition, PPE-SO3− molecules exhibit interesting optoelectronic properties, making the resulting graphene-based materials potentially useful in a variety of optoelectronic device applications.
Co-reporter:Fenghua Li, Jia Chai, Huafeng Yang, Dongxue Han, Li Niu
Talanta 2010 Volume 81(Issue 3) pp:1063-1068
Publication Date(Web):15 May 2010
DOI:10.1016/j.talanta.2010.01.061
A water-soluble and electroactive composite – Pt nanoparticles/polyelectrolyte-functionalized ionic liquid (PFIL)/graphene sheets (GS) nanocomposite was synthesized in one pot. The structure and composition of the Pt/PFIL/GS nanocomposite were studied by means of ultraviolet–visible (UV–vis) and X-ray photoelectron spectra (XPS). Scanning electron microscopy (SEM) and transmission electron microscope (TEM) images reveal Pt nanoparticles are densely dispersed on the transparent thin PFIL-functionalized graphene sheets. The obtained Pt/PFIL/GS nanocomposite-modified electrode was fabricated to simultaneously determine ascorbic acid (AA) and dopamine (DA) by cyclic voltammetry. It is worthwhile noting that the difference between the two peak potentials of AA and DA oxidation is over 200 mV, which leads to distinguishing AA from DA. The detection of increasing concentrations of AA in the presence of DA and the oxidation of continuous addition of DA in the presence of AA were also studied using differential pulse voltammetry. The proposed sensor in real sample analysis was also examined in human urine samples. Three independent oxidation peaks appear in urine sample containing AA and DA. Therefore, the Pt/PFIL/GS nanocomposite might offer a good possibility for applying it to routine analysis of AA and DA in clinical use.
Co-reporter:Fei Li, Jixia Song, Changsheng Shan, Dongmei Gao, Xiaoyu Xu, Li Niu
Biosensors and Bioelectronics 2010 Volume 25(Issue 6) pp:1408-1413
Publication Date(Web):15 February 2010
DOI:10.1016/j.bios.2009.10.037
A sensitive electrochemical detection scheme for morphine has been proposed by utilizing the ordered mesoporous carbon modified glassy carbon electrode (OMC/GCE). The electrochemical behaviour of morphine at the OMC/GCE was investigated by cyclic voltammetry. The modified electrode displayed a decrease in the overpotential (ca. 82 mV) and an obvious increase in the peak current (80 times) compared to the bare glassy carbon electrode (GCE). The results indicated that OMC/GCE remarkably enhanced electrocatalytic activity towards the oxidation of morphine. Linear response was found over the range from 0.1 μM to 20 μM with a high sensitivity of 1.74 μA/μM and low detection limit of 10 nM (S/N = 3). And the relative standard deviation was 0.86% (n = 5). Moreover, combining with a medium-exchange procedure, the OMC/GCE has also been successfully applied to the selective determination of morphine in urine samples with a low detection limit of 50 nM and satisfied recovery of 96.4%. The good results indicate that the OMC/GCE holds great promise in practical application.
Co-reporter:Changsheng Shan, Huafeng Yang, Dongxue Han, Qixian Zhang, Ari Ivaska, Li Niu
Biosensors and Bioelectronics 2010 Volume 25(Issue 6) pp:1504-1508
Publication Date(Web):15 February 2010
DOI:10.1016/j.bios.2009.11.009
It is firstly reported that low-potential NADH detection and biosensing for ethanol are achieved at an ionic liquid-functionalized graphene (IL-graphene) modified electrode. A substantial decrease (440 mV) in the overvoltage of the NADH oxidation was observed using IL-graphene/chitosan coating, with oxidation starting at ca. 0 V (vs. Ag|AgCl). And the NADH amperometric response at such a modified electrode is more stable (95.4% and 90% of the initial activity remaining after 10 min and 30 min at 1 mM NADH solution) than that at bare electrode (68% and 46%). Furthermore, the IL-graphene/chitosan-modified electrode exhibited a good linearity from 0.25 to 2 mM and high sensitivity of 37.43 μA mM−1 cm−2. The ability of IL-graphene to promote the electron transfer between NADH and the electrode exhibited a novel and promising biocompatible platform for development of dehydrogenase-based amperometric biosensors. With alcohol dehydrogenase (ADH) as a model, the ADH/IL-graphene/chitosan-modified electrode was constructed through a simple casting method. The resulting biosensor showed rapid and highly sensitive amperometric response to ethanol with a low detection limit (5 μM). Moreover, the proposed biosensor has been used to determine ethanol in real samples and the results were in good agreement with those certified by the supplier.
Co-reporter:Changsheng Shan, Huafeng Yang, Dongxue Han, Qixian Zhang, Ari Ivaska, Li Niu
Biosensors and Bioelectronics 2010 Volume 25(Issue 5) pp:1070-1074
Publication Date(Web):15 January 2010
DOI:10.1016/j.bios.2009.09.024
A novel glucose biosensor based on immobilization of glucose oxidase in thin films of chitosan containing nanocomposites of graphene and gold nanoparticles (AuNPs) at a gold electrode was developed. The resulting graphene/AuNPs/chitosan composites film exhibited good electrocatalytical activity toward H2O2 and O2. The wide linear response to H2O2 ranging from 0.2 to 4.2 mM (R = 0.998) at −0.2 V, high sensitivity of 99.5 μA mM−1 cm−2 and good reproducibility were obtained. The good electrocatalytical activity might be attributed to the synergistic effect of graphene and AuNPs. With glucose oxidase (GOD) as a model, the graphene/AuNPs/GOD/chitosan composite-modified electrode was constructed through a simple casting method. The resulting biosensor exhibited good amperometric response to glucose with linear range from 2 to 10 mM (R = 0.999) at −0.2 V and from 2 to 14 mM (R = 0.999) at 0.5 V, good reproducibility and detection limit of 180 μM. Glucose concentration in human blood was studied preliminarily. From 2.5 to 7.5 mM, the cathodic peak currents of the biosensor decrease linearly with increasing the glucose concentrations. The graphene/AuNPs/GOD/chitosan composites film shows prominent electrochemical response to glucose, which makes a promising application for electrochemical detection of glucose.
Co-reporter:Huafeng Yang, Fenghua Li, Changsheng Shan, Dongxue Han, Qixian Zhang, Li Niu and Ari Ivaska
Journal of Materials Chemistry A 2009 vol. 19(Issue 26) pp:4632-4638
Publication Date(Web):18 May 2009
DOI:10.1039/B901421G
Polydisperse, functionalized, chemically converted graphene (f-CCG) nanosheets, which can be homogeneously distributed into water, ethanol, DMF, DMSO and 3-aminopropyltriethoxysilane (APTS), were obtained via facile covalent functionalization with APTS. The resulting f-CCG nanosheets were characterized by FTIR, XPS, TGA, EDX, AFM, SEM, and TEM. Furthermore, the f-CCG nanosheets as reinforcing components were extended into silica monoliths. Compressive tests revealed that the compressive failure strength and the toughness of f-CCG-reinforced APTS monoliths at 0.1 wt% functionalized, chemically converted graphene sheets compared with the neat APTS monolith were greatly improved by 19.9% and 92%, respectively.
Co-reporter:Fenghua Li, Huafeng Yang, Changsheng Shan, Qixian Zhang, Dongxue Han, Ari Ivaska and Li Niu
Journal of Materials Chemistry A 2009 vol. 19(Issue 23) pp:4022-4025
Publication Date(Web):19 May 2009
DOI:10.1039/B902791B
Chemically converted graphene (CCG)/3,4,9,10-perylene tetracarboxylic acid (PTCA)/Au-ionic liquid (Au-IL) composites (CCG/PTCA/Au-IL) have been prepared by a chemical route that involves functionalization of CCG with PTCA followed by deposition of Au-IL. Transmission electron microscopy revealed well-distributed Au with a high surface coverage. The identity of the hybrid material was confirmed through X-ray diffraction and X-ray photoelectron spectroscopy. The CCG/PTCA/Au-IL composites exhibited good electrocatalytic behavior toward oxygen reduction. The results indicate that modification of CCG with Au-IL could play an important role in increasing the electrocatalytic activity of CCG.
Co-reporter:Huafeng Yang, Changsheng Shan, Fenghua Li, Dongxue Han, Qixian Zhang and Li Niu
Chemical Communications 2009 (Issue 26) pp:3880-3882
Publication Date(Web):05 Jun 2009
DOI:10.1039/B905085J
A facile method to obtain polydisperse chemically-converted graphene sheets that are covalently functionalized with ionic liquid was reported—the resulting graphene sheets, without any assistance from polymeric or surfactant stabilizers, can be stably dispersed in water, DMF, and DMSO.
Co-reporter:Changsheng Shan, Huafeng Yang, Jiangfeng Song, Dongxue Han, Ari Ivaska and Li Niu
Analytical Chemistry 2009 Volume 81(Issue 6) pp:2378
Publication Date(Web):February 19, 2009
DOI:10.1021/ac802193c
We first reported that polyvinylpyrrolidone-protected graphene was dispersed well in water and had good electrochemical reduction toward O2 and H2O2. With glucose oxidase (GOD) as an enzyme model, we constructed a novel polyvinylpyrrolidone-protected graphene/polyethylenimine-functionalized ionic liquid/GOD electrochemical biosensor, which achieved the direct electron transfer of GOD, maintained its bioactivity and showed potential application for the fabrication of novel glucose biosensors with linear glucose response up to 14 mM.
Co-reporter:Fenghua Li, Fei Li, Jixia Song, Jiangfeng Song, Dongxue Han, Li Niu
Electrochemistry Communications 2009 Volume 11(Issue 2) pp:351-354
Publication Date(Web):February 2009
DOI:10.1016/j.elecom.2008.11.042
Preparation of monodispersed platinum nanoparticles with average size 2.0 nm stabilized by amino-terminated ionic liquid was demonstrated. The resulting platinum nanoparticles (Pt-IL) retained long-term stability without special protection. The Pt-IL nanoparticles exhibited high electrocatalytic activity toward reduction of oxygen and oxidation of methanol. Rotating disk electrode voltammetry and rotating ring-disk electrode voltammetry confirmed that the Pt-IL films could catalyze an almost four-electron reduction of dioxygen to water.
Co-reporter:Qixian Zhang, Liansheng Jiao, Changsheng Shan, Guifu Yang, Xiaoyu Xu, Li Niu
Synthetic Metals 2009 Volume 159(Issue 14) pp:1422-1426
Publication Date(Web):July 2009
DOI:10.1016/j.synthmet.2009.03.019
The ferrocene-functionalised thiophene derivatives (TFn) with different length of oxyethylene chains were synthesized and polymerized chemically with iron (III) chloride as an oxidant. The resulting ferrocene-functionalised polythiophenes (PTFn) show good solubility in most solvents, such as chloroform (CHCl3), tetrahydrofuran (THF), acetone, etc. The structure and properties of the PTFn polymers were confirmed by IR, 1H NMR, AFM and photoluminescence (PL). The polymers PTFn show good redox activity with no attenuation of the electroactivity after multiple potential cycling.
Co-reporter:Dongmei Gao, Fei Li, Jixia Song, Xiaoyu Xu, Qixian Zhang, Li Niu
Talanta 2009 Volume 80(Issue 2) pp:479-483
Publication Date(Web):15 December 2009
DOI:10.1016/j.talanta.2009.07.007
A simple and environment friendly chemical route for detecting latent fingermarks by one-step single-metal nanoparticles deposition method (SND) was achieved successfully on several non-porous items. Gold nanoparticles (AuNPs) synthesized using sodium borohydride as reducing agent in the presence of glucose, were used as working solution for latent fingermarks detection. The SND technique just needs one step to obtain clear ridge details in a wide pH range (2.5–5.0), whereas the standard multi-metal deposition (MMD) technique requires six baths in a narrow pH range (2.5–2.8). The SND is very convenient to detect latent fingermarks in forensic scene or laboratory for forensic operators. The SND technique provided sharp and clear development of latent fingermarks, without background staining, dramatically diminished the bath steps.
Co-reporter:Fei Li, Jixia Song, Dongmei Gao, Qixian Zhang, Dongxue Han, Li Niu
Talanta 2009 Volume 79(Issue 3) pp:845-850
Publication Date(Web):15 August 2009
DOI:10.1016/j.talanta.2009.05.011
A simple and rapid method for morphine detection has been described based on electrochemical pretreatment of glassy carbon electrode (GCE) which was treated by anodic oxidation at 1.75 V, following potential cycling in the potential range from 0 V to 1.0 V vs. Ag|AgCl reference electrode. The sensitivity for morphine detection was improved greatly and the detection limit was 0.2 μM. The reproducibility of the voltammetric measurements was usually less than 3% RSD for six replicate measurements. Moreover, this method could readily discriminate morphine from codeine. And an electrochemical detection of morphine in spiked urine sample was succeeded with satisfactory results.
Co-reporter:Yanfei Shen, Yuanjian Zhang, Dongxue Han, Zhijuan Wang, Daniel Kuehner, Li Niu
Talanta 2009 Volume 78(Issue 3) pp:805-808
Publication Date(Web):15 May 2009
DOI:10.1016/j.talanta.2008.12.056
Co-reporter:Fenghua Li, Jixia Song, Fei Li, Xiaodan Wang, Qixian Zhang, Dongxue Han, Ari Ivaska, Li Niu
Biosensors and Bioelectronics 2009 Volume 25(Issue 4) pp:883-888
Publication Date(Web):15 December 2009
DOI:10.1016/j.bios.2009.08.044
Multiwalled carbon nanotubes@SnO2-Au (MWCNTs@SnO2-Au) composite was synthesized by a chemical route. The structure and composition of the MWCNTs@SnO2-Au composite were confirmed by means of transmission electron microscopy, X-ray photoelectron and Raman spectroscopy. Due to the good electrocatalytic property of MWCNTs@SnO2-Au composite, a glucose biosensor was constructed by absorbing glucose oxidase (GOD) on the hybrid material. A direct electron transfer process is observed at the MWCNTs@SnO2-Au/GOD-modified glassy carbon electrode. The glucose biosensor has a linear range from 4.0 to 24.0 mM, which is suitable for glucose determination by real samples. It should be worthwhile noting that, from 4.0 to 12.0 mM, the cathodic peak currents of the biosensor decrease linearly with increasing the glucose concentrations in human blood. Meanwhile, the resulting biosensor can also prevent the effects of interfering species. Moreover, the biosensor exhibits satisfying reproducibility, good operational stability and storage stability. Therefore, the MWCNTs@SnO2-Au/GOD biocomposite could be promisingly applied to determine blood sugar concentration in the practical clinical analysis.
Co-reporter:Fenghua Li, Zhonghua Wang, Changsheng Shan, Jiangfeng Song, Dongxue Han, Li Niu
Biosensors and Bioelectronics 2009 Volume 24(Issue 6) pp:1765-1770
Publication Date(Web):15 February 2009
DOI:10.1016/j.bios.2008.09.005
Gold nanoparticles stabilized by amino-terminated ionic liquid (Au-IL) have been in situ noncovalently deposited on poly(sodium 4-styrene-sulfonate) (PSS)-functionalized multiwalled carbon nanotubes (MWCNTs) to form a MWCNTs/PSS/Au-IL nanocomposite. PSS can interact with MWCNTs through hydrophobic interaction. Amino-terminated ionic liquid was applied to reduce aqueous HAuCl4, and the resulting gold nanoparticles were attached to the PSS-functionalized MWCNTs simultaneously. Most gold nanoparticles dispersed well on the functionalized MWCNTs. Transmission electron microscopy, Raman and X-ray photoelectron spectroscopy were used to confirm the composition and structure of the nanocomposites. The resulting MWCNTs/PSS/Au-IL composite exhibits good electrocatalysis toward oxygen and hydrogen peroxide reduction. And good biocompatibility with glucose oxidase was also demonstrated due to its good biocatalysis toward glucose substrate, which offered a friendly environment for the immobilization of biomolecules. Such bionanocomposite provides us potential applications in fabrication of biosensors. The resulting biosensor exhibits good response to glucose with a low detection limit 25 μM. It also has excellent reproducibility, satisfied operational stability and good storage stability.
Co-reporter:Changsheng Shan, Huafeng Yang, Dongxue Han, Qixian Zhang, Ari Ivaska and Li Niu
Langmuir 2009 Volume 25(Issue 20) pp:12030-12033
Publication Date(Web):September 21, 2009
DOI:10.1021/la903265p
Graphene sheets functionalized covalently with biocompatible poly-l-lysine (PLL) were first synthesized in an alkaline solution. PLL-functionalized graphene is water-soluble and biocompatible, which makes it a novel material promising for biological applications. Graphene sheets played an important role as connectors to assemble these active amino groups of poly-l-lysine, which provided a very biocompatible environment for further functionalization, such as attaching bioactive molecules. As an example, an amplified biosensor toward H2O2 based on linking peroxidase onto PLL-functionalized graphene was investigated.
Co-reporter:Zhijuan Wang, Qixian Zhang, Daniel Kuehner, Ari Ivaska and Li Niu
Green Chemistry 2008 vol. 10(Issue 9) pp:907-909
Publication Date(Web):29 Jul 2008
DOI:10.1039/B806453A
Stable gold nanoparticles with average size 1.7 nm synthesized by an amine-terminated ionic liquid showed enhanced electrocatalytic activity and high stability.
Co-reporter:Yuanjian Zhang, Yanfei Shen, Daniel Kuehner, Shuixing Wu, Zhongmin Su, Shen Ye and Li Niu
Chemical Communications 2008 (Issue 36) pp:4273-4275
Publication Date(Web):17 Jul 2008
DOI:10.1039/B805789C
Both the behavior and the general key factors for assembling flexible SWNT films at the water/oil interface were investigated; the electron transfer, one of the most fundamental chemical processes, at the SWNT-sandwiched water/oil interface was also firstly illustrated using scanning electrochemical microscopy.
Co-reporter:Zhijuan Wang, Qixian Zhang, Dan Kuehner, Xiaoyu Xu, Ari Ivaska, Li Niu
Carbon 2008 Volume 46(Issue 13) pp:1687-1692
Publication Date(Web):November 2008
DOI:10.1016/j.carbon.2008.07.020
Multiwalled carbon nanotube (MWCNT)/ionic liquid/gold nanoparticle hybrid materials have been prepared by a chemical route that involves functionalization of MWCNT with amine-terminated ionic liquids followed by deposition of Au. Transmission electron microscopy revealed well-distributed Au with a narrow size distribution centered around 3.3 nm. The identity of the hybrid material was confirmed through Raman and X-ray photoelectron spectroscopy. It showed good electrocatalytic behavior toward oxygen reduction, relative to glassy carbon electrode. The results indicate that modification of MWCNT with ionic liquids and Au could play an important role in increasing the electrocatalytic activity of MWCNT.
Co-reporter:Zhijuan Wang, Meiye Li, Pingping Su, Yuanjian Zhang, Yanfei Shen, Dongxue Han, Ari Ivaska, Li Niu
Electrochemistry Communications 2008 Volume 10(Issue 2) pp:306-310
Publication Date(Web):February 2008
DOI:10.1016/j.elecom.2007.12.011
Horseradish peroxidase (HRP) was incorporated into multiwalled carbon nanotube/thionine/Au (MTAu) composite film by electrostatic interactions between positively charged HRP and negatively charged MTAu composite. The results of electrochemical impedance spectroscopy (EIS) confirmed adsorption of HRP on the surface of MTAu modified GC electrode. Moreover, the electrochemical results showed that HRP retained its bioactivity and bioelectrocatalytical activity, and also showed good direct electron transfer behavior on such a composite film.
Co-reporter:Xuefeng Ding, Dongxue Han, Zhijuan Wang, Xiaoyu Xu, Li Niu, Qiang Zhang
Journal of Colloid and Interface Science 2008 Volume 320(Issue 1) pp:341-345
Publication Date(Web):1 April 2008
DOI:10.1016/j.jcis.2008.01.004
Polyaniline/magnetite nanocomposites consisting of polyaniline (PANI) nanorods surrounded by magnetite nanoparticles were prepared via an in situ self-assembly process in the presence of PANI nanorods. The synthesis is based on the well-known chemical oxidative polymerization of aniline in an acidic environment, with ammonium persulfate (APS) as the oxidant. An organic acid (dodecylbenzenesulfonic acid, DBSA) was used to replace the conventional strong acidic (1 M HCl) environment. Here, dodecylbenzenesulfonic acid is used not only as dopant, but also as surfactant in our reaction system. So, DBSA can excellently control the morphology and size of PANI nanorods and magnetite particles. Magnetite particles were formed simultaneously during sedimentation, and the formed nanorods were also decorated by the particles. The resulting PANI/magnetite composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). It is found that PANI/magnetite nanorod composites have uniform size, superparamagnetism and a small mass fraction of magnetite, thermal stabilization even at a higher temperature.Polyaniline/magnetite nanorod composites consisting of polyaniline (PANI) nanorods surrounded by magnetite (Fe3O4) nanoparticles were prepared via an in situ self-assembly process in the presence of PANI nanorods.
Co-reporter:Zhijuan Wang, Junhua Yuan, Dongxue Han, Yuanjian Zhang, Yanfei Shen, Daniel Kuehner, Li Niu and Ari Ivaska
Crystal Growth & Design 2008 Volume 8(Issue 6) pp:1827-1832
Publication Date(Web):May 13, 2008
DOI:10.1021/cg060895c
This paper describes a facile route for simultaneous synthesis of polyaniline (PANI) nanotubules and gold nanoplates. The inner diameter of PANI nanotubules was less than 10 nm and the length was several micrometers. At the same time, uniform single-crystal gold nanoplates with thicknesses of tens of nanometers were obtained. The resulting products are characterized further by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and FT-IR spectroscopy. The effect of concentration ratios of the HAuCl 4 to aniline to this synthesis is also studied.
Co-reporter:Zhijuan Wang, Junhua Yuan, Min Zhou, Li Niu, Ari Ivaska
Applied Surface Science 2008 Volume 254(Issue 20) pp:6289-6293
Publication Date(Web):15 August 2008
DOI:10.1016/j.apsusc.2008.02.080
Abstract
Single-crystal Au nanosheets and fcc gold nanocrystals of uniform size were synthesized by a novel and simple route. The results of field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) indicated the formation of the single-crystal structure of gold nanosheets and fcc nanocrystals. Energy-dispersive analysis of X-ray (EDAX) showed absorbance of cetyltrimethylammonium bromide (CTAB) molecules onto the surface of gold nanostructures. Moreover, zeta potential measurements showed that CTAB-coated nanostructures were positively charged and the zeta potential remained almost the same upon centrifugation and redispersion of the resulting nanostructures in methanol, confirming the high stability of the surfactant-protected nanocomposites. Evolution of the nanostructures during the reaction was monitored by TEM observations. The results indicated that the formation of the gold nanostructures followed a two-step mechanism with a bilayer CTAB structure on the surface of the gold nanostructures.
Co-reporter:Junhua Yuan, Zhijuan Wang, Yuanjian Zhang, YanFei Shen, Dongxue Han, Qixian Zhang, Xiaoyu Xu, Li Niu
Thin Solid Films 2008 Volume 516(Issue 18) pp:6531-6535
Publication Date(Web):31 July 2008
DOI:10.1016/j.tsf.2008.03.007
A simple layer-by-layer (LBL) electrostatic adsorption technique was developed for deposition of films composed of alternating layers of positively charged poly(diallyldimethylammonium chloride) (PDDA) and negatively charged multiwall carbon nanotubes bearing platinum nanoparticles (Pt-CNTs). PDDA/Pt-CNT film structure and morphology up to six layers were characterized by scanning electron microscopy and ultraviolet-visible spectroscopy, showing the Pt-CNT layers to be porous and uniformly deposited within the multilayer films. Electrochemical properties of the PDDA/Pt-CNT films, as well as electrocatalytic activity toward methanol oxidation, were investigated with cyclic voltammetry. Significant activity toward anodic methanol oxidation was observed and is readily tunable through changing film thickness and /or platinum-nanoparticle loading. Overall, the observed properties of these PDDA/Pt-CNT multilayer films indicated unique potential for application in direct methanol fuel cell.
Co-reporter:Fei Jia, Changsheng Shan, Fenghua Li, Li Niu
Biosensors and Bioelectronics 2008 Volume 24(Issue 4) pp:945-950
Publication Date(Web):1 December 2008
DOI:10.1016/j.bios.2008.07.057
A novel glucose biosensor based on immobilization of glucose oxidase (GOD) in thin films of polyethylenimine-functionalized ionic liquid (PFIL), containing a mixture of carbon nanotubes (CNT) and gold nanoparticles (AuNPs) and deposited on glassy carbon electrodes, was developed. Direct electrochemistry of glucose oxidase in the film was observed, with linear glucose response up to 12 mM. The PFIL-stabilized gold nanoparticles had a diameter of 2.4 ± 0.8 nm and exhibited favorable stability (stored even over one month with invisible change in UV–vis spectroscopic measurements). In addition, CNT were also well dispersed in the PFIL matrix, then, the resulting CNT/AuNPs/PFIL composites film showed high electrocatalytic activity toward reduction of hydrogen peroxide and oxygen. Here, PFIL, due to its high ionic conductivity, good solubility to CNT, and stability to nanoparticles, played an important role in constructing stable CNT/AuNPs/PFIL/GOD composites. And good biocompatibility of PFIL also offered a friendly environment for the immobilization of biomolecules.
Co-reporter:Yanfei Shen Dr.;Yuanjian Zhang Dr.;Daniel Kuehner Dr.;Guifu Yang Dr.;Fuyu Yuan Dr.
ChemPhysChem 2008 Volume 9( Issue 15) pp:2198-2202
Publication Date(Web):
DOI:10.1002/cphc.200800449
Abstract
We propose a simple but efficient, rapid, and quantitative ion-responsive micelle system based on counter-anion exchange of a surfactant with an imidazolium unit. The ion-exchange reaction results in the amphiphilic-to-hydrophobic transition of the imidazolium salt, leading to the destruction of the micelles, which has been successfully applied to controlled release and emulsification. The proposed design offers a novel alternative stimulus to control these smart physical aggregates besides pH, temperature and light—with extra advantages. Our finding greatly benefits both fundamental research and industry.
Co-reporter:Yanfei Shen, Yuanjian Zhang, Xuepeng Qiu, Haiquan Guo, Li Niu and Ari Ivaska
Green Chemistry 2007 vol. 9(Issue 7) pp:746-753
Publication Date(Web):15 Mar 2007
DOI:10.1039/B616452H
As a green process, electrochemistry in aqueous solution without a supporting electrolyte has been described based on a simple polyelectrolyte-functionalized ionic liquid (PFIL)-modified electrode. The studied PFIL material combines features of ionic liquids and traditional polyelectrolytes. The ionic liquid part provides a high ionic conductivity and affinity to many different compounds. The polyelectrolyte part has a good stability in aqueous solution and a capability of being immobilized on different substrates. The electrochemical properties of such a PFIL-modified electrode assembly in a supporting electrolyte-free solution have been investigated by using an electrically neutral electroactive species, hydroquinone (HQ) as the model compound. The partition coefficient and diffusion coefficient of HQ in the PFIL film were calculated to be 0.346 and 4.74 × 10−6 cm2 s−1, respectively. Electrochemistry in PFIL is similar to electrochemistry in a solution of traditional supporting electrolytes, except that the electrochemical reaction takes place in a thin film on the surface of the electrode. PFILs are easily immobilized on solid substrates, are inexpensive and electrochemically stable. A PFIL-modified electrode assembly is successfully used in the flow analysis of HQ by amperometric detection in solution without a supporting electrolyte. The results indicate a green electrochemical methodology in supporting electrolyte-free solution and a potential application in amperometric detection in a flow system without any supporting electrolyte in the solution, such as the high performance liquid chromatography electrochemical detection (HPLC-ECD) system.
Co-reporter:Zhijuan Wang, Meiye Li, Yuanjian Zhang, Junhua Yuan, Yanfei Shen, Li Niu, Ari Ivaska
Carbon 2007 Volume 45(Issue 10) pp:2111-2115
Publication Date(Web):September 2007
DOI:10.1016/j.carbon.2007.05.018
Multi-walled carbon nanotube (MWCNT)/thionine/gold nanoparticle composites were prepared by binding gold nanoparticles to the surfaces of thionine-coated carbon nanotubes. TEM images show gold nanoparticles distributed uniformly on nanotube walls and ends. UV–Vis, Raman, FT-IR, and zeta potential measurements were used to examine the properties of the resulting products. The composites demonstrate significant electrocatalytic activity for oxygen reduction. Although only gold nanoparticles were investigated here, the method could be easily extended to attach other metallic nanoparticles to the sidewalls of carbon nanotubes.
Co-reporter:Fan Yang, Liansheng Jiao, Yanfei Shen, Xiaoyu Xu, Yuanjian Zhang, Li Niu
Journal of Electroanalytical Chemistry 2007 Volume 608(Issue 1) pp:78-83
Publication Date(Web):15 September 2007
DOI:10.1016/j.jelechem.2007.05.004
In this work, a polyelectrolyte-functionalized ionic liquid (PFIL) was firstly incorporated into a sol–gel organic–inorganic hybrid material (PFIL/sol–gel). This new composite material was used to immobilize glucose oxidase on a glassy carbon electrode. An enhanced current response towards glucose was obtained, relative to a control case without PFIL. In addition, chronoamperometry showed that electroactive mediators diffused at a rate 10 times higher in the apparent diffusion coefficient in PFIL-containing matrices. These findings suggest a potential application in bioelectroanalytical chemistry.
Co-reporter:Dongxue Han, Guifu Yang, Jixia Song, Li Niu, Ari Ivaska
Journal of Electroanalytical Chemistry 2007 Volume 602(Issue 1) pp:24-28
Publication Date(Web):1 April 2007
DOI:10.1016/j.jelechem.2006.11.027
Poly(4-styrene sulfonate)-doped poly(3,4-ethylenedioxythiophene) (PEDOT/PSS) films with ring-, arrow-, and bubble-like micro-structures have been electrochemically generated simply by a one-step cyclic voltammetry in an aqueous media. Influences of applied potentials and surfactant/dopant-PSS on morphology of the resulting film were investigated, and a gas bubble template mechanism has been proposed. The result confirmed a well-doping of PSS in the PEDOT film. Electrochemical property and conductivity of the micro-structured PEDOT/PSS film were investigated further. Similar preparation with potential applications in fabrication of micro-devices and micro-sensors can be extended to other micro-structured conducting polymers.
Co-reporter:Zhijuan Wang, Junhua Yuan, Meiye Li, Dongxue Han, Yuanjian Zhang, Yanfei Shen, Li Niu, Ari Ivaska
Journal of Electroanalytical Chemistry 2007 Volume 599(Issue 1) pp:121-126
Publication Date(Web):1 January 2007
DOI:10.1016/j.jelechem.2006.09.021
Polyaniline/multi-walled carbon nanotube/gold (PANI/MWNT/Au) composite film was synthesized via a two-step electrochemical process. First the mixture of aniline and MWNT was heated at refluxing and was electropolymerized. Then, the Au nanoparticles were dispersed into the film of PANI/MWNT by electrochemical reduction of HAuCl4. The morphology of sample was analyzed by scanning electron microscopy (SEM). Raman measurement indicates a well electrochemical deposition of PANI on MWNT, and XPS result confirms the formation of Au0 nanoparticles. Further, cyclic voltammograms show that the film exhibits a good electrochemical activity and electrocatalysis towards ascorbic acid. Based on these investigations, a formation mechanism of the PANI/MWNT composite film was proposed.
Co-reporter:Junhua Yuan, Dongxue Han, Yuanjian Zhang, YanFei Shen, Zhijuan Wang, Qixian Zhang, Li Niu
Journal of Electroanalytical Chemistry 2007 Volume 599(Issue 1) pp:127-135
Publication Date(Web):1 January 2007
DOI:10.1016/j.jelechem.2006.09.025
The electrostatic layer-by-layer assembly method was successfully used in a multilayer buildup of polyaniline (PANI) and platinum nanocrystals encapsulated in the carboxyl-terminated poly(amidoamine) dendrimers (generation 4.5 G4.5COOH) (Pt-G4.5COOH NPs) on solid substrates. Multilayer growth was monitored by ultraviolet–visible (UV–vis) absorption spectroscopy. The AFM observation revealed a molecularly smooth (PANI/Pt-G4.5COOH NPs)m multilayer film which is rougher and thicker than the multilayer of PANI and G4.5COOH (G4.5COOH/PANI)m. The PANI/Pt-G4.5COOH NPs multilayers show a fast surface-confined electron-exchange process at the Au electrode in an acid solution, and remains stable, reversible and electroactive, even in neutral solution. Furthermore, the multilayers show a strong electrocatalytic response towards CO oxidation and O2 reduction, and the catalytic capability can be easily tuned by the control of multilayer thickness.
Co-reporter:Dongxue Han, Jixia Song, Xuefeng Ding, Xiaoyu Xu, Li Niu
Materials Chemistry and Physics 2007 Volume 105(2–3) pp:380-384
Publication Date(Web):15 October 2007
DOI:10.1016/j.matchemphys.2007.05.002
Poly(aniline-co-anthranilic acid) (PANANA) nanorods in bundles was prepared successfully in an alcohol/aqueous media without assistance of any other kinds of acids. Anthranilic acid played all roles of monomer, acid-media provider, and dopant in the reaction system, and ammonium persulfate (APS) served as the oxidant. The morphologies of PANANA nanorods in bundles were investigated by scanning electron microscopy (SEM). Influences of the monomer molar ratio on the resulting morphology were investigated. Moreover the formation mechanism of the nanostructured copolymer was proposed. FT-IR, UV–vis and X-ray diffraction (XRD) measurements were used to confirm the molecular and electrical structure of the self-doped PANANA. The intrinsic properties, such as conductivity, electrochemical redox activity and room-temperature solubility of the resulting copolymer were explored.
Co-reporter:Dongxue Han, Yuanjian Zhang, Yanfei Shen, Zhijuan Wang, Li Niu
Materials Letters 2007 Volume 61(Issue 17) pp:3632-3634
Publication Date(Web):July 2007
DOI:10.1016/j.matlet.2006.12.003
Superhigh aspect-ratio Cu–thiourea (Cu(tu)) nanowires have been synthesized in large quantity via a fast and facile method. Nanowires of Cu(tu)Cl·0.5H2O and Cu(tu)Br·0.5H2O were found to be 60–100 nm and 100–200 nm in diameter, and could extend to several millimeters in length. It is found to be the most convenient and facile approach to the fabrication of one-dimensional superhigh aspect-ratio nanomaterials in large scale so far.
Co-reporter:Tao Yang;Zhuang Li;Shaojun Dong
Frontiers of Chemistry in China 2007 Volume 2( Issue 1) pp:1-5
Publication Date(Web):2007 March
DOI:10.1007/s11458-007-0001-0
The applications of scanning probe microscopy (SPM) in intrinsically conducting polymer research is briefly reviewed, including morphology observation, nanofabrication, microcosmic electrical property measurements, electrochemistry researches, in-situ measurements of film thickness change, and so on. At the same time, some important variations of SPM and the related techniques are briefly introduced. Finally, the future development of SPM in the study of intrinsically conducting polymers is prospected.
Co-reporter:Yuanjian Zhang, Yanfei Shen, Dongxue Han, Zhijuan Wang, Jixia Song and Li Niu
Journal of Materials Chemistry A 2006 vol. 16(Issue 47) pp:4592-4597
Publication Date(Web):05 Oct 2006
DOI:10.1039/B612317A
Single-walled carbon nanotubes (SWCNTs) as reinforcing components were extended into silica monoliths and thin films via covalent functionalization for the first time. Silica materials have poor mechanical attributes, which limit their applications. Because of the extreme flexibility of SWCNTs and their large interfacial area, they may be very intriguing as reinforcing fillers for the silica matrix. To get more uniform dispersion and stronger interfacial interaction, SWCNTs were covalently functionalized with silane, and then integrated into silica via a sol–gel process, and their properties were also compared with those of pristine SWCNTs. Results show that the silane-functionalized nanotubes resulted in better mechanical properties (for example, 33% increase in stress, and 53% increase in toughness), as well as higher electron-transfer kinetics.
Co-reporter:Peng HOU, Dong-xue HAN, Li NIU, Hai-bo LIN
Chemical Research in Chinese Universities 2006 Volume 22(Issue 4) pp:493-499
Publication Date(Web):July 2006
DOI:10.1016/S1005-9040(06)60149-9
Co-reporter:Yuanjian Zhang;Yanfei Shen;Junhua Yuan;Dongxue Han;Zhijuan Wang;Qixian Zhang Dr.
Angewandte Chemie 2006 Volume 118(Issue 35) pp:
Publication Date(Web):28 JUL 2006
DOI:10.1002/ange.200600120
Nicht nur als „grüne“ Solventien sind ionische Flüssigkeiten zu betrachten, sondern sie eignen sich auch, um unabhängige Komponenten zu hoch funktionalisierten Verbindungen zu verknüpfen. Beispielsweise werden einwandige Kohlenstoffnanoröhren (SWNTs) durch einfachen Anionenaustausch mit anderen Komponenten kombiniert (siehe Bild).
Co-reporter:Yuanjian Zhang;Yanfei Shen;Junhua Yuan;Dongxue Han;Zhijuan Wang;Qixian Zhang Dr.
Angewandte Chemie International Edition 2006 Volume 45(Issue 35) pp:
Publication Date(Web):28 JUL 2006
DOI:10.1002/anie.200600120
No longer simply “green” solvents, ionic liquids can be used as backbones to integrate independent components into a multifunctional compound. For example, single-walled carbon nanotubes (SWNTs) are coupled with various anions (X−) by a simple anion-exchange reaction (see picture).
Co-reporter:Kun Huang Dr.;Yuanjian Zhang;Yunze Long Dr.;Junhua Yuan;Dongxue Han;Zhijuan Wang Dr.;Zhaojia Chen Dr.
Chemistry - A European Journal 2006 Volume 12(Issue 20) pp:
Publication Date(Web):21 APR 2006
DOI:10.1002/chem.200501527
One-dimensional gold/polyaniline (Au/PANI-CSA) coaxial nanocables with an average diameter of 50–60 nm and lengths of more than 1 μm were successfully synthesized by reacting aniline monomer with chlorauric acid (HAuCl4) through a self-assembly process in the presence of D-camphor-10-sulfonic acid (CSA), which acts as both a dopant and surfactant. It was found that the formation probability and the size of the Au/PANI-CSA nanocables depends on the molar ratio of aniline to HAuCl4 and the concentration of CSA, respectively. A synergistic growth mechanism was proposed to interpret the formation of the Au/PANI-CSA nanocables. The directly measured conductivity of a single gold/polyaniline nanocable was found to be high (≈77.2 S cm−1). Hollow PANI-CSA nanotubes, with an average diameter of 50–60 nm, were also obtained successfully by dissolving the Au nanowire core of the Au/PANI-CSA nanocables.
Co-reporter:Yanfei Shen, Yuanjian Zhang, Qixian Zhang, Li Niu, Tianyan You and Ari Ivaska
Chemical Communications 2005 (Issue 33) pp:4193-4195
Publication Date(Web):20 Jul 2005
DOI:10.1039/B507688A
An all-purpose approach to immobilize ionic liquids onto solid supports is proposed by chemical grafting on a polyelectrolyte carrier.
Co-reporter:Zhijuan Wang, Liansheng Jiao, Tianyan You, Li Niu, Shaojun Dong, Ari Ivaska
Electrochemistry Communications 2005 Volume 7(Issue 9) pp:875-878
Publication Date(Web):September 2005
DOI:10.1016/j.elecom.2005.06.004
Self-doped poly(o-aminobenzenesulfonic-acid-co-aniline) (abbr. p(oASA-co-Ani)) nanoflowers were prepared by an electrochemical preparation without any other supporting electrolytes. The images of scanning electron microscope show that the nanoflowers are uniform. In addition, the results obtained from the cyclic voltammetry indicate that it exhibits a remarkable electroactivity at an extended pH range from 3 to 13.5.
Co-reporter:Yuanjian Zhang, Yanfei Shen, Daniel Kuehner, Shuixing Wu, Zhongmin Su, Shen Ye and Li Niu
Chemical Communications 2008(Issue 36) pp:NaN4275-4275
Publication Date(Web):2008/07/17
DOI:10.1039/B805789C
Both the behavior and the general key factors for assembling flexible SWNT films at the water/oil interface were investigated; the electron transfer, one of the most fundamental chemical processes, at the SWNT-sandwiched water/oil interface was also firstly illustrated using scanning electrochemical microscopy.
Co-reporter:Huafeng Yang, Changsheng Shan, Fenghua Li, Dongxue Han, Qixian Zhang and Li Niu
Chemical Communications 2009(Issue 26) pp:
Publication Date(Web):
DOI:10.1039/B905085J
Co-reporter:Yuanjian Zhang, Keisuke Fugane, Toshiyuki Mori, Li Niu and Jinhua Ye
Journal of Materials Chemistry A 2012 - vol. 22(Issue 14) pp:
Publication Date(Web):
DOI:10.1039/C2JM00044J
Co-reporter:Jia Chai, Fenghua Li, Yuwei Hu, Qixian Zhang, Dongxue Han and Li Niu
Journal of Materials Chemistry A 2011 - vol. 21(Issue 44) pp:NaN17929-17929
Publication Date(Web):2011/10/12
DOI:10.1039/C1JM13631C
A novel hollow AuPd (hAuPd) alloy nanostructure with a rough surface was fabricated via a facile one-pot simultaneous reduction of Au(III) and Pd(I) and then assembled on ionic liquid-grafted graphene sheets by electrostatic interaction to form graphene–metal hybrid nanomaterials under mild conditions. The resulting hollow alloy nanostructure and graphene nanocomposites were then characterized using many techniques, such as transmission electron microscopy (TEM), high-resolution TEM (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), element analysis mapping, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), confirming that the alloy nanoparticles with hollow cores had been successfully synthesized by one step galvanic replacement and attached firmly onto the graphene sheets. The electrocatalytic ability of the resulting nanocomposites for direct oxidation of formic acid was also explored. The hollow AuPd alloy nanospheres, especially the graphene-supported nanocomposites, exhibited striking electrocatalytic activities which show potential application in fuel cells.
Co-reporter:Huafeng Yang, Fenghua Li, Changsheng Shan, Dongxue Han, Qixian Zhang, Li Niu and Ari Ivaska
Journal of Materials Chemistry A 2009 - vol. 19(Issue 26) pp:NaN4638-4638
Publication Date(Web):2009/05/18
DOI:10.1039/B901421G
Polydisperse, functionalized, chemically converted graphene (f-CCG) nanosheets, which can be homogeneously distributed into water, ethanol, DMF, DMSO and 3-aminopropyltriethoxysilane (APTS), were obtained via facile covalent functionalization with APTS. The resulting f-CCG nanosheets were characterized by FTIR, XPS, TGA, EDX, AFM, SEM, and TEM. Furthermore, the f-CCG nanosheets as reinforcing components were extended into silica monoliths. Compressive tests revealed that the compressive failure strength and the toughness of f-CCG-reinforced APTS monoliths at 0.1 wt% functionalized, chemically converted graphene sheets compared with the neat APTS monolith were greatly improved by 19.9% and 92%, respectively.
Co-reporter:Weidong Ruan, Zhicheng Lu, Tieli Zhou, Bing Zhao and Li Niu
Analytical Methods (2009-Present) 2010 - vol. 2(Issue 6) pp:NaN687-687
Publication Date(Web):2010/04/09
DOI:10.1039/C0AY00068J
A facile and powerful method to form micropatterns, based on nanosphere lithography and layer-by-layer self-assembly, is described in this paper. A monolayer of hexagon close-packed polystyrene (PS) spheres (av 600 nm) was employed as the template. A positively charged polyelectrolyte of poly(diallydimethylammonium) chloride was used as adhesive to absorb oppositely charged spherical Au (av 17 nm) and spherical Ag (av 12 nm), respectively. Both the PS and substrates were coated by colloidal nanoparticles. After removal of the PS template, a micropatterning surface was obtained. Scanning electron microscopy and atomic force microscopy were used to characterize the morphologies. These resulting patterns can be used as good surface-enhanced Raman scattering (SERS) substrates. The enhancement factor is calculated to be 104 ∼ 105. This is a simple and facile technique for surface modification of metal micropatterns with SERS analytical application.
Co-reporter:Min Zhou, Shiyu Gan, Lijie Zhong, Xiandui Dong and Li Niu
Physical Chemistry Chemical Physics 2011 - vol. 13(Issue 7) pp:NaN2779-2779
Publication Date(Web):2010/12/13
DOI:10.1039/C0CP01692F
We present a more general expression for the relationship of potential dependence, which implies that a change in the interfacial drop across the interface has little effect on the free energy of the reaction, but mainly affects the surface concentration of reactant in each phase. Abundant experimental results from several well-known groups are analyzed in great detail to confirm our conclusion. At the same time, we define a new parameter named Frumkin correction factor to describe this relationship of potential dependence, which expresses the thermodynamic effect of double diffuse layers within both phases in contrast with the so often suggested kinetic electron-transfer (ET) coefficient; we also find that it depends on two intimately related aspects: the charges of reactive species and the ratio of the diffuse layer potential to the total potential within each phase, so it is quite arbitrary to ignore the diffuse layer effect in the aqueous phase just because of its relatively small values. In addition, a fascinating question on the inverted region at liquid/liquid interfaces has been successfully interpreted by an opposite surface concentration effect, which was often considered as a kinetic Marcus inverse by most groups.
Co-reporter:Fenghua Li, Huafeng Yang, Changsheng Shan, Qixian Zhang, Dongxue Han, Ari Ivaska and Li Niu
Journal of Materials Chemistry A 2009 - vol. 19(Issue 23) pp:NaN4025-4025
Publication Date(Web):2009/05/19
DOI:10.1039/B902791B
Chemically converted graphene (CCG)/3,4,9,10-perylene tetracarboxylic acid (PTCA)/Au-ionic liquid (Au-IL) composites (CCG/PTCA/Au-IL) have been prepared by a chemical route that involves functionalization of CCG with PTCA followed by deposition of Au-IL. Transmission electron microscopy revealed well-distributed Au with a high surface coverage. The identity of the hybrid material was confirmed through X-ray diffraction and X-ray photoelectron spectroscopy. The CCG/PTCA/Au-IL composites exhibited good electrocatalytic behavior toward oxygen reduction. The results indicate that modification of CCG with Au-IL could play an important role in increasing the electrocatalytic activity of CCG.
Co-reporter:Di Wei, Piers Andrew, Huafeng Yang, Yuanyuan Jiang, Fenghua Li, Changsheng Shan, Weidong Ruan, Dongxue Han, Li Niu, Chris Bower, Tapani Ryhänen, Markku Rouvala, Gehan A. J. Amaratunga and Ari Ivaska
Journal of Materials Chemistry A 2011 - vol. 21(Issue 26) pp:NaN9767-9767
Publication Date(Web):2011/06/03
DOI:10.1039/C1JM10826C
Different formulations of solution-processable graphene have been characterised as electrode materials for use in electrochemical energy storage devices. Graphene was fabricated by chemical reduction of exfoliated graphene oxide (GO), and modified with either p-type (e.g. polyaniline) or n-type anionic groups (poly(styrenesulfonate) (PSS−) and poly[2,5-bis(3-sulfonatopropoxy)-1,4-ethynylphenylene-alt-1,4-ethynylphenylene] sodium salt (PPE-SO3−) anion). Solutions of these graphene compounds were deposited on charge collecting electrodes and used as battery cathodes. Electrodes using the anionically-modified graphene inks containing anatase titanate (TiO2) nanoparticles show improved performance over pristine graphene ink as well as the p-type conducting polymer modified ones. In addition, the open circuit voltage of batteries based on TiO2 has been boosted over 3 V with good cyclability when mixed with the graphene ink. Combined with a polymer electrolyte, this work suggests a feasible route towards fully printable rechargeable lithium batteries based on graphene inks. This approach is both versatile and scalable and is adaptable to a wide variety of applications.
Co-reporter:Yuwei Hu, Fenghua Li, Xiaoxue Bai, Dan Li, Shucheng Hua, Kaikai Wang and Li Niu
Chemical Communications 2011 - vol. 47(Issue 6) pp:NaN1745-1745
Publication Date(Web):2010/12/01
DOI:10.1039/C0CC04514D
Negative-charge change and conformation transition upon DNA immobilization and hybridization on functionalized graphene sheets were monitored by the EIS technique and adopted as the signal for label-free electrochemical DNA hybridization detection.
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![Benzenesulfonic acid,4-[2-[4-(dimethylamino)phenyl]diazenyl]-](http://img.cochemist.com/ccimg/600/502-02-3.png)
![Benzenesulfonic acid,4-[2-[4-(dimethylamino)phenyl]diazenyl]-](http://img.cochemist.com/ccimg/600/502-02-3_b.png)
