Hydroxyl-dependent Evolution of Oxygen Vacancies Enables the Regeneration of BiOCl photocatalyst
Hood, Zachary D.
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
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AbstractPhotoinduced oxygen vacancies (OVs) are widely investigated as a vital point defect in wide-band-gap semiconductors. Still, the formation mechanism of OVs remains unclear in various materials. To elucidate the formation mechanism of photoinduced OVs in bismuth oxychloride (BiOCl), we synthesized two surface hydroxyl discrete samples in light of the discovery of the significant variance of hydroxyl groups before and after UV light exposure. It is noted that OVs can be obtained easily after UV light irradiation in the sample with surface hydroxyl groups, while variable changes were observed in samples without surface hydroxyls. Density functional theory (DFT) calculations reveal that the binding energy of Bi-O is drastically influenced by surficial hydroxyl groups, which is intensely correlated to the formation of photoinduced OVs. Moreover, DFT calculations reveal that the adsorbed water molecules are energetically favored to dissociate into separate hydroxyl groups at the OV sites via proton transfer to a neighboring bridging oxygen atom, forming two bridging hydroxyl groups per initial oxygen vacancy. This result is consistent with the experimental observation that the disappearance of photoinduced OVs and the recovery of hydroxyl groups on the surface of BiOCl after exposed to a H2O(g)-rich atmosphere, and finally enables the regeneration of BiOCl photocatalyst. Here, we introduce new insights that the evolution of photoinduced OVs is dependent on surface hydroxyl groups, which will lead to the regeneration of active sites in semiconductors. This work is useful for controllable designs of defective semiconductors for applications in photocatalysis and photovoltaics.
CitationWu S, Xiong J, Sun J, Hood ZD, Zeng W, et al. (2017) Hydroxyl-Dependent Evolution of Oxygen Vacancies Enables the Regeneration of BiOCl Photocatalyst. ACS Applied Materials & Interfaces 9: 16620–16626. Available: http://dx.doi.org/10.1021/acsami.7b01701.
SponsorsThis work has been supported by the National Natural Science Foundation of China (51302329) and the Fundamental Research Funds for the Central Universities (106112015CDJXY130010). We gratefully acknowledge the help from Mr. Yuqi Zhang and Yuan Yuan for helpful discussions. The preparation of this manuscript was also supported by the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. ZDH gratefully acknowledges a graduate fellowship from the National Science Foundation under Grant DGE-1148903 and the Georgia Tech-ORNL Fellowship. Lin Gu acknowledges the National Program on Key Basic Research Project (2014CB921002), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant XDB07030200), and National Natural Science Foundation of China (51522212, 51421002).
PublisherAmerican Chemical Society (ACS)