1. Formation of hydroperoxo (–OOH) species on the surface of self-doped Bi2.15WO6: reactivity towards As(III) oxidation.
- Author
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Wang, Xiang-Ming, Wu, Song-Hai, Ren, Hai-Tao, Zhu, Peng-Yue, Wang, Cong, Liu, Yong, Sun, Shi-Wei, Zhang, Xiao-Cong, Lin, Yi-Ying, Meng, Zi-He, Jia, Shao-Yi, and Han, Xu
- Abstract
Bi
2+x WO6 is a cost-effective and environmentally friendly photocatalyst that shows high reactivity in the oxidation of various contaminants under visible light. However, under alkaline conditions, the reactive oxidative species in the Bi2+x WO6 system are still not clear yet. In this study, it is observed that the oxidation rates of As(III) increase with increasing pH values in the Bi2.15 WO6 system. Photoluminescence and the Mott–Schottky analyses confirm that OH− promotes the separation and transfer of photogenerated electron–hole pairs over Bi2.15 WO6 , thus facilitating the oxidation of As(III). Electron spin resonance spectra analysis and quenching experiments rule out contributions of •OH, O2 ˙− ,1 O2 and superoxo species to As(III) oxidation and indicate that surface –OOH and/or H2 O2 are indeed the predominant species under alkaline conditions. The improved production of H2 O2 by H-donors such as glucose and phenol, as well as the UV-vis diffuse reflectance and Raman analyses, further confirms the formation of surface –OOH on Bi2.15 WO6 under alkaline conditions. In the dark, the significant higher oxidation rate of As(III) by H2 O2 –Bi2.15 WO6 than that by H2 O2 alone reveals that surface −OOH, instead of H2 O2 , plays an important role in As(III) oxidation. This study enriches our understanding of the diversity of reactive oxygen species (ROS) in the Bi2.15 WO6 system and gives new insight into the mechanism involved in the oxidation of As(III) under alkaline conditions. [ABSTRACT FROM AUTHOR]- Published
- 2020
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