Jing Sui,Zhengxin Peng,Nan Lu,KaiCheng Qian,Xiaofan Zhang,Tong Wei,Renhong Li,Xiaoqing Yan
Developing high-efficiency and low-cost hydrogen production catalysts is essential to alleviate environmental problems. Indium sulfide is an effective catalyst for photocatalytic water-splitting reactions to produce hydrogen (H2). However, the high hole–electron recombination rate of indium-based nanoparticles restricts their practical applications. To overcome this, we fabricated a P-doped In2S3 catalyst with S vacancies through a calcination method. When the P-doping magnitude is 0.4 wt%, the resultant catalyst reports the optimal photo-catalytic activity (3853.4 μmol h−1 g−1) in the presence of formaldehyde, molecular oxygen and visible light illumination, which is more than 6.3 times higher than that of pure In2S3 (603.3 μmol h−1 g−1). The synergetic effect of sulfur vacancies and the P-doping can lead to a narrower band gap in the In2S3 nanoparticles, thereby promoting photogenerated hole–electron pair separation and photo-catalytic hydrogen production ability. We find that molecular O2 plays a crucial role in promoting the oxidation of formaldehyde to produce photo-catalytic H2. During the entire reaction process, molecular oxygen will not be consumed (similar to a cocatalyst). Benefiting from the enhanced charge separation and transfer processes, the P-doped In2S3 with S vacancies exhibits excellent photo-catalytic hydrogen production performance from formaldehyde solution.
TiO 2 quantum dots (QDs) are synthesized and used to prepare thin films as novel blocking layers (TiO 2 -QD-BLs) at conductive glass/TiO 2 interfaces by spin coating method. The electron recombination at conductive glass/polysulfide electrolyte interfaces can be reduced significantly after the insertion of TiO 2 -QD-BLs in the photoelectrodes. The effects of different thickness of TiO 2 -QD-BLs on photovoltaic performance of CdS QDs sensitized solar cells are investigated. It is found that the cells with 641 nm thick TiO 2 -QD-BLs show the highest power conversion efficiency of about 3.66% under full sunlight illumination (100 mW cm −2 , AM 1.5 G), which is obviously higher than that of the cells without TiO 2 -QD-BLs in the photoelectrodes (1.99%).
Ya-Ping Que,Jian Weng,Lin-Hua Hu,Ji-Huai Wu,Song-Yuan Dai
The morphology, microstructure and crystallography of titanium dioxide (TiO 2 ) have great effect on the photoelectric performance of dye-sensitized solar cells (DSSCs). Herein, flower-like 3D TiO 2 microstructures based on well-defined high-crystalline nanosheets are synthesized through a facile hydrothermal method . Especially, morphological evolution process and mechanism of this hierarchical structure are investigated. Due to the highly crystalline nature and smaller surface area of these nanosheets , the corresponding device shows an extremely high open-current voltage up to 0.84 V, which results from the less electron recombination. When applied as a scattering layer on top of the nanoparticle layer, the power conversion efficiency (PCE) can be significantly improved and give birth to a PCE value of 9.6%, which is 24.6% higher than that of an analogous device using nanoparticles (NP) (7.7%). As reflected by diffusion reflection spectra, intensity of the modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) and electrochemical impedance spectra (EIS), this hierarchical structure can not only enhance light harvesting, but also reduce electron recombination, facilitate electron transport and improve electron collection efficiency.
Li Chen,Weilin Chen,Jianping Li,Jiabo Wang,Enbo Wang
Graphical Sandwich filling : Polyoxometalate (POM) can act as an electron-transfer medium to decrease electron recombination in a photoelectric device. POM/TiO 2 is prepared as an electronic interface layer by a facile layer-by-layer self-assembly method. This interface layer is added to the photoanode of quantum dot-sensitized solar cells (QDSCs) for improved performance of the QDSCs. Electron recombination occurring at the TiO 2 /quantum dot sensitizer/electrolyte interface is the key reason for hindering further efficiency improvements to quantum dot sensitized solar cells (QDSCs). Polyoxometalate (POM) can act as an electron-transfer medium to decrease electron recombination in a photoelectric device owing to its excellent oxidation/reduction properties and thermostability. A POM/TiO 2 electronic interface layer prepared by a simple layer-by-layer self-assembly method was added between fluorine-doped tin oxide (FTO) and mesoporous TiO 2 in the photoanode of QDSCs, and the effect on the photovoltaic performance was systematically investigated. Photovoltaic experimental results and the electron transmission mechanism show that the POM/TiO 2 electronic interface layer in the QDSCs can clearly suppress electron recombination, increase the electron lifetime, and result in smoother electron transmission. In summary, the best conversion efficiency of QDSCs with POM/TiO 2 electronic interface layers increases to 8.02 %, which is an improvement of 25.1 % compared with QDSCs without POM/TiO 2 . This work first builds an electron-transfer bridge between FTO and the quantum dot sensitizer and paves the way for further improved efficiency of QDSCs.
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