Kinetics analysis of oxygen vacancies in TiO2 solar water reduction: Revealing effects and eliminating disadvantages

Jinbo Xue; Han Zhang; Rongfeng Guan; Tianwu Liu; Jiaqi Gao; Xuguang Liu; Min Wu; Kunpeng Guo; Husheng Jia; Qianqian Shen

doi:10.1016/j.jcis.2022.10.108

Kinetics analysis of oxygen vacancies in TiO₂ solar water reduction: Revealing effects and eliminating disadvantages

J Colloid Interface Sci. 2023 Jan 15;630(Pt B):382-393. doi: 10.1016/j.jcis.2022.10.108. Epub 2022 Oct 26.

Authors

Jinbo Xue¹, Han Zhang², Rongfeng Guan³, Tianwu Liu⁴, Jiaqi Gao⁴, Xuguang Liu⁴, Min Wu², Kunpeng Guo², Husheng Jia⁵, Qianqian Shen²

Affiliations

¹ Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024, PR China; Department of Chemistry, Tsinghua University, Beijing 100084, PR China. Electronic address: xuejinbo@tyut.edu.cn.
² Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024, PR China.
³ Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Yancheng 224051, PR China.
⁴ Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024, PR China; College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, PR China.
⁵ Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024, PR China; College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, PR China; Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering, Taiyuan 030032, PR China.

PMID: 36332431
DOI: 10.1016/j.jcis.2022.10.108

Abstract

A consensus is yet to be reached on the effects of oxygen vacancy (V_O) on the performance of TiO₂ for photocatalytic water splitting as contrasting viewpoints have been presented in the latest researches. Herein, a comprehensive set of spectroelectrochemical methods are deployed to clearly reveal the advantages and disadvantages of V_O on the performance of TiO₂. The results indicate that surface V_O improves the photocatalytic activity while bulk V_O has a negative effect on the water reduction performance of TiO₂. Intensity-modulated photocurrent spectroscopy (IMPS) and UV-vis spectroscopy provide compelling evidence that the improvement of H₂ evolution can be attributed to the presence of defect level, while the low interface charge transfer efficiency caused by surface V_O limits the further improvement of photocatalytical H₂ evolution, which can be alleviated by an organic hole transport coating. The density functional theory (DFT) and surface photovoltaic (SPV) analyses confirm that the built-in field between TiO₂ and hole molecules is the reason for the interface charge transfer efficiency improvement. Our findings provide a comprehensive understanding of V_O in TiO₂ by carrier behavior analysis and a scheme to further promote the photocatalytic performance.

Keywords: Black TiO(2); Built-in field; Carrier behavior; DFT; Defect energy level; IMPS; Oxygen vacancy; Photocatalytic H(2) evolution.