Co-reporter:Qizhang Huang, Yueyun Fang, Jifu Shi, Yanliang Liang, Yanqing Zhu, and Gang Xu
ACS Applied Materials & Interfaces October 18, 2017 Volume 9(Issue 41) pp:36431-36431
Publication Date(Web):September 25, 2017
DOI:10.1021/acsami.7b11940
Flower-like molybdenum disulfide (MoS2) with rich edge sites has been prepared by the hydrothermal method. The edge sites possess polarity due to the noncentrosymmetric Mo–S on exposed (100) facets and thus show a strong electrostatic attraction toward polar species. The flower-like MoS2 can be used as small-molecule carriers for the model drug, Rhodamine B (RhB). The results prove that flower-like MoS2 have fast adsorption kinetics and perform a switchable accumulation/release with response to the solvent polarity. An outstanding reusability can be found in flower-like MoS2 due to little cargo retention, and the recycle of adsorption can be repeated 100 times with above 88.5% of the adsorption capacity retained. The flower-like MoS2 with solvent polarity-triggered loading/release can be extended to controlled release and color switch of display.Keywords: adsorption; molybdenum disulfide; polarity; reusability; solvents;
Co-reporter:Yongjun Zhan, Xiudi Xiao, Yuan Lu, Ziyi Cao, Shuai Qi, Changmeng Huan, Cantao Ye, Haoliang Cheng, Jifu Shi, Xueqing Xu, Gang Xu
Surfaces and Interfaces 2017 Volume 9(Volume 9) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.surfin.2017.09.002
•Atomic diffusion induces the formation of crystalline nuclei at low temperatures.•Drastic diffusion reaction deteriorates the performance of VO2 thin film.•The unbalance of interfacial stress leads to disappearance of thermochromic proformance.In this paper, the multilayer thin films with SiNx/NiCr/NiCrOx/VO2/NiCrOx/NiCr/SiNx structure were prepared by reactive magnetron sputtering at room temperature and subsequently rapid thermal annealing (RTA) in air. The effects of annealing temperature on the microstructure and thermocheromic performance of the VO2 multilayer thin films were systemacially investigated by UV–Vis-NIR, XRD, SEM, XPS and TEM. The results showed that the crystalline VO2 multilayer thin films can be obtained as the temperature rose from room temperature to 301 °C within 6 s, and the high thermochromic performance with solar modulation (∆Tsol) of 17.2%, luminous transmittance (Tlum) of 26.9% and phase transition temperature (Tc) of 60 °C can be acquired as the temperature rose from room temperature to 571 °C within 10 s, which indicates the VO2 multilayer thin films show the good antioxidation. Based on growth mechanism of VO2 multilayer thin films, it can be found that the atomic diffusion may form crystal nucleation and induce the rapid crystallization of VO2 thin film at low temperature, the drastic diffusion reaction results in the degeneration of crystallinity and performance of VO2 film with increasing temperature. Finally, the unbalance of interfacial stress lead to the rupture of the films, and the VO2 was completely oxidized into V2O5. The exploration of the growth mechanism provides the basis for the optimization of the film structure and annealing parameters, so as to promote the practical application of VO2 multilayer thin films with high thermochromic performance.
Co-reporter:Yuan Lu, Xiudi Xiao, Ziyi Cao, Yongjun Zhan, Haoliang Cheng, Gang Xu
Applied Surface Science 2017 Volume 425(Volume 425) pp:
Publication Date(Web):15 December 2017
DOI:10.1016/j.apsusc.2017.07.035
•Electrospinning was firstly used to fabricate PMMA-VO2 composite smart film.•Electrospun smart film was transparent via simple heat treatment.•VO2 embedded in the fiber and aligned along the fiber axis.•Antioxidation of VO2 was improved because of inner distribution in the fiber.The monoclinic phase vanadium dioxide VO2 (M) based transparent thermochromic smart films were firstly fabricated through heat treatment of opaque VO2-based composite nanofibrous mats, which were deposited on the glass substrate via electrospinning technique. Noteworthily, the anti-oxidation property of VO2 smart film was improved due to inner distribution of VO2 in the polymethylmethacrylate (PMMA) nanofibers, and the composite mats having water contact angle of 165° determined itself good superhydrophobic property. Besides, PMMA nanofibrous mats with different polymer concentrations demonstrated changeable morphology and fiber diameter. The VO2 nanoparticles having diameter of 30–50 nm gathered and exhibited ellipse-like or belt-like structure. Additionally, the solar modulation ability of PMMA-VO2 composite smart film was 6.88% according to UV–Vis-NIR spectra. The research offered a new notion for fabricating transparent VO2 thermochromic material.
Co-reporter:Yanqing Zhu;Jifu Shi;Qizhang Huang;Yueyun Fang;Leilei Wang
RSC Advances (2011-Present) 2017 vol. 7(Issue 54) pp:34125-34130
Publication Date(Web):2017/07/04
DOI:10.1039/C7RA04238H
A new kind of superhydrophobic (SH) solar selective absorber (SSA) used in a low-temperature flat plate solar collector is proposed. Getting rid of the glass cover can improve the performance of the flat plate solar collector. SSA with a SH coating can maintain the efficiency in a practical outdoor working environment. The SH coating can be made by a simple Sol–Gel method; the water contact angle of SH SSA can reach up to 157° and the sliding angle is less than 2°. The self-cleaning of SH SSA can be realized by rainwater or natural wind. The solar absorptance of SH SSA is still 89.46% after treating in a neutral salt spray for 48 h, which indicates that SH SSA has good corrosion resistance and is suitable to the outdoor environment. Thermal performance tests show that the flat plat solar collector with SH SSA has excellent thermal performance for low-temperature application.
Co-reporter:Zhu Yanqing;Shi jifu;Huang Qizhang;Wang Leilei;Xu Gang
Chemical Communications 2017 vol. 53(Issue 15) pp:2363-2366
Publication Date(Web):2017/02/16
DOI:10.1039/C6CC09558E
A novel and facile approach to produce TiO2-based superhydrophobic–superhydrophilic patterns by UV or solar irradiation without a photomask is presented. The fabricated superhydrophobic–superhydrophilic patterns with excellent mechanical properties have long lifetimes in outdoor applications or other UV environments because of a self-supply of low surface tension material.
Co-reporter:Yanqing Zhu, Jifu Shi, Yujian Li, Leilei Wang, Qizhang Huang, Gang Xu
Energy Conversion and Management 2017 Volume 146(Volume 146) pp:
Publication Date(Web):15 August 2017
DOI:10.1016/j.enconman.2017.05.031
•A scalable linear Fresnel reflector which can supply different temperatures is proposed.•Inclination design of the mechanical structure is used to reduce the end losses.•The maximum thermal efficiency of 64% is achieved in Guangzhou.This paper proposes a scalable linear Fresnel reflector (SLFR) solar system. The optical mirror field which contains an array of linear plat mirrors closed to each other is designed to eliminate the inter-low shading and blocking. Scalable mechanical mirror support which can place different number of mirrors is designed to supply different temperatures. The mechanical structure can be inclined to reduce the end losses. Finally, the thermal efficiency of the SLFR with two stage mirrors is tested. After adjustment, the maximum thermal efficiency of 64% is obtained and the mean thermal efficiency is higher than that before adjustment. The results indicate that the end losses have been reduced effectively by the inclination design and excellent thermal performance can be obtained by the SLFR after adjustment.
Co-reporter:Q.Z. Huang, J.F. Shi, L.L. Wang, Y.J. Li, L.W. Zhong, G. Xu
Thin Solid Films 2016 610() pp: 19-25
Publication Date(Web):1 July 2016
DOI:10.1016/j.tsf.2016.05.010
Co-reporter:Guiming Peng, Jiamin Wu, Yong Zhao, Xueqing Xu, Gang Xu and Alexander Star
RSC Advances 2014 vol. 4(Issue 87) pp:46987-46991
Publication Date(Web):19 Sep 2014
DOI:10.1039/C4RA09134E
One-dimensional TiO2 nanostructures that have large specific surface area have broadened their applications in solar cells and water splitting, but their synthesis still remains a challenge. In this report, vertically ordered rutile TiO2 nanowires with an ultra-high coverage density of 2.4 × 1011 cm−2 and ultra-small width of barely ∼16 nm were synthesized on transparent conducting oxide by a facile solvothermal reaction using methanol and aqueous hydrochloride as solvent. The nanowires were fabricated with Sb2S3 into solid-state solar cells, which yielded a power conversion efficiency of 2.03%. Such a photoanode showed reduced electron recombination, due to moderate wire fusion at the bottom.
Co-reporter:Guiming Peng, Xueqing Xu, Fengjiao Mei, Gang Xu, Jiamin Wu, Di Gao, James E. Ellis, Yong Zhao, Yan Xing and Alexander Star
RSC Advances 2014 vol. 4(Issue 95) pp:53335-53343
Publication Date(Web):07 Oct 2014
DOI:10.1039/C4RA10611C
Hierarchical nanostructures grown directly on transparent conducting oxides hold the promise of overcoming the limitations of current semiconductor-sensitized solar cells based on random networks of nanoparticles. Here, we develop a facile substrate placement angle-dependent hydrothermal process to grow dandelion-like TiO2 nanostructures directly on transparent conductive oxides. TiO2 nanocrystals grown in solution during the synthesis process are found to promote the dandelion-like structure. By using these TiO2 nanostructures as photoanodes, Sb2S3 as the sensitizer, and P3HT as the hole-transporting material, we demonstrate fabrication of all-solid-state semiconductor-sensitized solar cells, which yield solar power conversion efficiency up to 4.71%. Electrochemical impedance spectroscopy indicates that moderate rod fusion at the base beneficially reduces electron recombination in the device. This work provides an innovative method for growing branched, one-dimensional TiO2 nanostructures that can be used for energy harvesting and storage.
Co-reporter:Xiudi Xiao, Haoliang Cheng, Guoping Dong, Yougen Yu, Lihua Chen, Lei Miao and Gang Xu
CrystEngComm 2013 vol. 15(Issue 6) pp:1095-1106
Publication Date(Web):06 Nov 2012
DOI:10.1039/C2CE26262B
VO2 nanobelts with metal–semiconductor properties were prepared through low temperature hydrothermal reaction and post annealing. X-Ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), differential scanning calorimetry (DSC) and UV-vis-NIR spectrophotometry were employed to investigate the evolution of structure, morphology and properties of the VO2 nanobelts. The results illustrate that the pure VO2 (B) nanobelts can be obtained by hydrothermal reaction. The shape of the nanobelts evolves with hydrothermal temperature, time and reactant concentration. With the increasing of hydrothermal temperature from 160 °C to 200 °C, the nanobelts become homogenous and regular. The regular nanobelts are also obtained by the decrease of V2O5 concentration. Samples prepared at 200 °C over 48 h have superior morphology and crystallinity. After annealing, VO2 (B) can be transformed into VO2 (M), which is dependent on the hydrothermal conditions. Samples prepared at 160 °C over 48 h and 180 °C over 48 h can be transformed into VO2 (M) at 450 °C over 2 h, while samples obtained at 200 °C over 48 h should be annealed at 500 °C for 2 h. The nanobelts are transformed into irregular nanostructures, nanorods and nanobelts at the hydrothermal temperatures of 160 °C, 180 °C and 200 °C, respectively. However, samples prepared at 200 °C over 48 h with a V2O5 concentration of 0.0125 M can keep the intact nanobelts after annealing. The DSC analysis proves that the VO2 (M) shows good phase transition behavior around 68 °C and the phase transition temperature can be reduced to 58 °C by 0.5 at% tungsten doping. After mixing the VO2 (M) with acrylic resin, the visible transmission of the VO2 composite coating on glass is up to 52.2% and the solar modulation at 2000 nm is up to 31.5%, which means that it is a good candidate for smart windows.
Co-reporter:Lihua Chen, Chunming Huang, Gang Xu, Stuart L. Hutton, Lei Miao
Materials Characterization 2013 Volume 75() pp:8-12
Publication Date(Web):January 2013
DOI:10.1016/j.matchar.2012.09.010
We demonstrate a simple route for the preparation of new three-dimensionally interconnected hierarchically porous anatase TiO2 foams via a dual-templating approach. The macropores in TiO2 foams are induced through a process of sintering the polyurethane foams template, while a surfactant templating agent promotes the formation of mesopores in the walls of a macroporous monolith of TiO2 foam. The macropore sizes of interconnected networks can be tuned by varying the pores per linear inch of polyurethane foams. This single step method of synthesis from cheap commercially available chemicals is suitable for mass production of three-dimensionally interconnected macro/mesoporous TiO2 foams.Highlights► New hierarchically porous TiO2 foams were synthesized by sol–gel template method. ► Polyurethane foams as a hard template and EO106PO70EO106 as a soft template ► Suitable method for mass production with cheap chemicals ► The method could be extended to synthesis of other hierarchical porous oxides.
Co-reporter:Chunming Huang;Lihua Chen;Lei Miao
Journal of Sol-Gel Science and Technology 2012 Volume 63( Issue 1) pp:103-107
Publication Date(Web):2012 July
DOI:10.1007/s10971-012-2769-8
In this paper, we report on the obtention of highly ordered VO2 nanotube arrays synthesized by the simple sol–gel template method. Techniques of transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy were used to characterize the morphology and structure of the as-synthesized nanotube arrays. It is found that the size of the as-obtained nanotubes has the dimension of 180–220 nm in outer diameter, 110–140 nm in inner diameter and up to 10 μm in length. The results show that as-synthesized sample is assigned to VO2 (B) phase in expected V/O ratio with V existing in the +4 oxidation state.
Co-reporter:Xiudi Xiao, Lei Miao, Gang Xu, Limei Lu, Zhanmin Su, Ning Wang, Sakae Tanemura
Applied Surface Science 2011 Volume 257(Issue 24) pp:10729-10736
Publication Date(Web):1 October 2011
DOI:10.1016/j.apsusc.2011.07.088
Abstract
Copper oxide thin films as solar selective absorbers were conveniently prepared by one-step chemical conversion method. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis–NIR spectra and Fourier transform infrared (FTIR) spectra were employed to characterize the composition, structure and optical properties of thin films. The results indicated that the composition, structure and optical properties of thin films were greatly influenced by reaction temperature, time and concentration of NaOH. When reaction temperature was fixed at 40 °C, the as-prepared films consist of pure cubic Cu2O. The surface morphology of thin films was changed from square-like structure (reaction time ≤ 25 min) to porous belt-like structure (reaction time ≥ 30 min) with the elongation of reaction time. While for thin films prepared at 60 °C and 80 °C, single Cu2O was observed after 5 min reaction. When reaction time is longer than 5 min, CuO appears and the content of CuO is increasing with the elongation of reaction time. With the increase of reaction temperature, the belt-like structure was easily formed for 60 °C/10 min and 80 °C/5 min. Decreasing concentration of NaOH also could result in the formation of CuO and porous belt-like structure. Simultaneously, the film thickness is increasing with the increase of reaction time, temperature and concentration. Films containing CuO with belt-like structure exhibited high absorptance (>0.9), and the emissivity of films increased with elongation of reaction time. Combination of the composition, structure and optical properties, it can be deduced that the porous belt-like structure like as a light trap can greatly enhance absorbance (α), while the composition, thickness and roughness of thin films can greatly influence the emissivity (ɛ). The highest photo-thermal conversion efficiency was up to 0.86 (α/ɛ = 0.94/0.08) for thin films prepared at 80 °C/5 min, which proved that the CuOx thin films can be served as high performance solar selective absorbers.
Co-reporter:Gang Xu, Chun-Ming Huang, Masato Tazawa, Ping Jin, Li-Hua Chen
Optics Communications 2009 Volume 282(Issue 5) pp:896-902
Publication Date(Web):1 March 2009
DOI:10.1016/j.optcom.2008.11.045
The optical properties of Au nanoparticles deposited on thermochromic thin films of VO2 are investigated using spectroscopy. A localized modification on the transmittance spectrum of VO2 film is formed due to the presence of Au nanoparticles which exhibit localized surface plasmon resonance (LSPR) in the visible-near IR region. The position of the modification wavelength region shows a strong dependence on the Au mass thickness and shifts toward the red as it increases. On the other hand, it was found that the LSPR of Au nanoparticles can be thermally tunable because of the thermochromism of the supporting material of VO2. The LSPR wavelength, λSPR, shifts to the blue with increasing temperature, and shifts back to the red as temperature decreases. A fine tuning is achieved when the temperature is increased in a stepwise manner.
Co-reporter:Jifu Shi, Xueqing Xu, Gang Xu
Procedia Engineering (2012) Volume 27() pp:38-46
Publication Date(Web):1 January 2012
DOI:10.1016/j.proeng.2011.12.422
In this paper, two electrolytes with water and dimethylformamide as solvents are prepared for the quantum-dot-sensitized solar cells. The impedance spectroscopy method is used to study the influence of the solvents of electrolyte on the performance of quantum-dot-sensitized solar cells. The results show that the cell with dimethylformamide as the solvent exhibits higher charge-transfer resistance between the electrons in TiO2 film and the polysulfide in the electrolyte, leading to longer life time and diffusion length of the electrons. Meanwhile, the dimethylformamide can negatively shift the conduction band edge of TiO2. However, the solubility of the polysulfide in dimethylformamide is too low to meet the requirements of quantum-dot-sensitized solar cells, which results in the lower efficiency of the solar cells based on dimethylformamide compared with that of water.
Co-reporter:Zhu Yanqing, Shi jifu, Huang Qizhang, Wang Leilei and Xu Gang
Chemical Communications 2017 - vol. 53(Issue 15) pp:NaN2366-2366
Publication Date(Web):2017/01/25
DOI:10.1039/C6CC09558E
A novel and facile approach to produce TiO2-based superhydrophobic–superhydrophilic patterns by UV or solar irradiation without a photomask is presented. The fabricated superhydrophobic–superhydrophilic patterns with excellent mechanical properties have long lifetimes in outdoor applications or other UV environments because of a self-supply of low surface tension material.
