Construction and photocatalytic properties of WS 2 /BiOCl heterojunction
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RESEARCH PAPER
Construction and photocatalytic properties of WS2 /BiOCl heterojunction Shuyan Qi · Xueting Liu · Ninglong Ma · Huanyan Xu
Received: 26 May 2020 / Accepted: 10 November 2020 © Springer Nature B.V. 2020
Abstract Bismuth oxyhalide BiOX (X=Cl, Br, I) as a new photocatalyst, its series of BiOX, and composite photocatalyst materials have attracted much attention. In this paper, we used Bi(NO3 )3 ·5H2 O, NaOH, and WS2 as raw materials to prepare WS2 /BiOCl heterojunction composite materials by in situ construction method, and using X-ray diffraction, EDS element mapping, and other analytical means found the crystallization of WS2 /BiOCl composite materials. With the increase of the mass ratio of WS2 , the XRD peak of WS2 in the composite became sharp gradually. The visible light response range of BiOCl increased, and the band gap became narrow. The recombination probability of photogenerated electron-hole pair decreased. BiOCl (1–2 μm) was stacked on the WS2 (2–5 μm) layer, and formed the WS2 /BiOCl heterostructure. The results showed that 7%-WS2 /BiOCl had the best adsorption effect, and the degradation efficiency reached 95.83% at 240 min. At the same time, the active groups in the photocatalytic degradation process are ·OH and h+ . Through the first-order kinetic simulation, the reaction rate constant of 7%WS2 /BiOCl was 0.0155 min−1 , which was 4.2 times
S. Qi () · X. Liu · N. Ma · H. Xu School of Materials Science and Engineering, Harbin University of Science and Technology, Harbin 150040, China e-mail: [email protected]
that of BiOCl. After four cycles of experiments, it still had stable photocatalytic activity. Keywords Photocatalyst · Composite · Heterostructure · Nanostructured catalysts
Introduction At present, organic dye wastewater has become one of the main water pollution sources. Most of the dyes are toxic, carcinogenic, and difficult to degrade, which pose a great threat to human health. Semiconductor photocatalytic degradation technology provides a new and effective way to solve energy and environmental problems. Due to the unique band structure of metal sulfides, oxides, and bismuth oxyhalide, their application in semiconductor photocatalytic degradation technology has been widely concerning. However, a series of problems, such as photocorrosion, narrow light absorption range, and high electron-hole pair recombination probability, always occur in a single sulfide; bismuth oxyhalide has a unique layered structure with wide band gap, large energy required to stimulate electron migration, weak or no response to visible light, and poor photocatalytic performance. Reducing surface defects (Zhao et al. 2014), constructing heterojunction (Cao et al. 2011; Zhang et al. 2018), adding auxiliary agents (Park et al. 2011), and modifying semiconductor materials with precious
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metals such as gold and platinum (Sreethawong and Yoshikawa 2012) have been proved to be effective ways to reduce electron-hole pair recombination. TiO2 can decompose water to produce H2 and O2 under th
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