Reducing Packing Factor of ZnIn 2 S 4 to Promote Photocatalytic Activity
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doi: 10.1007/s40242-020-0308-7
Article
Reducing Packing Factor of ZnIn2S4 to Promote Photocatalytic Activity HU Keyan1,2, XU Zian3, LIU Yiting4 and HUANG Fuqiang1,5* 1. State Key Laboratory of High-performance Ceramics and Super Fine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, P. R. China; 2. School of Mechanical and Electrical Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333403, P. R. China; 3. Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong 999077, P. R. China; 4. State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, P. R. China; 5. Beijing National Laboratory for Molecular Sciences and State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China Abstract Due to the quite sluggish charge-carrier separation in semiconductor photocatalysts, the photocatalytic activity of these materials is still far inferior than anticipated. Herein, a novel approach to reducing the packing factor(PF) of ZnIn2S4 semiconductors to improve the charge-carrier separation is offered. The well-crystallized Zn 1-xIn2S4-x(x=0, 0.05, 0.1) powders were productively prepared through solid-state reactions. Their structures were verified by the highresolution transmission electron microscopy, powder X-ray diffraction, and X-ray photoelectron spectroscopy. The PF values of Zn1–xIn2S4–x(x=0, 0.05, 0.1) samples were calculated to be 0.683, 0.651, and 0.618, respectively. The reduction of the PF for Zn 1-xIn2S4-x with increasing x can promote the separation of photoexcited carriers, and this process was endorsed by their photoelectric response and photoluminescence emission spectra. The Zn 0.9In2S3.9 sample with a lower PF value presents roughly 21 times higher photocurrent density and four times higher photodegrading rate of methyl orange than those of pristine ZnIn 2S4. Keywords Charge-carrier separation; Packing factor; Zn1- xIn2S4-x; Solid state reaction; Photocatalytic activity
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Introduction
The classic photoelectric conversion procedure of semiconductors involves the photoabsorption, the separation of photoexcited charge carriers, and the subsequent transfer of electrons-holes pairs[1―6]. Compared to metal oxides, metal sulfides possess a fairly narrow bandgap for harvesting more visible light because the S 3p orbital energy is higher than that of O2p[7]. However, the photocatalytic performance of many metal sulfides is still disappointed. CdS has a fair photocatalytic activity but suffers from photocorrosion [8,9]. Some metal sulfides are of slow separation and transfer of photoexcited carriers to cause poor photocatalytic activity [10―15]. To eliminate the bottleneck of the photoelectric conversion process in these metal sulfides, it is essential to accelerate their photoexcited carrier separation and subsequently transfer [16―19]. Packing factor(PF) is generally us
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