Asymmetric surfaces endow Janus bismuth oxyhalides with enhanced electronic and catalytic properties for the hydrogen evolution reaction

Haixi Pan; Liping Feng; Pengfei Liu; Xiaoqi Zheng; Xiaodong Zhang

doi:10.1016/j.jcis.2022.03.009

Asymmetric surfaces endow Janus bismuth oxyhalides with enhanced electronic and catalytic properties for the hydrogen evolution reaction

J Colloid Interface Sci. 2022 Jul:617:204-213. doi: 10.1016/j.jcis.2022.03.009. Epub 2022 Mar 4.

Authors

Haixi Pan¹, Liping Feng², Pengfei Liu¹, Xiaoqi Zheng¹, Xiaodong Zhang¹

Affiliations

¹ State Key Lab of Solidification Processing, College of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shanxi 710072, China.
² State Key Lab of Solidification Processing, College of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shanxi 710072, China. Electronic address: lpfeng@nwpu.edu.cn.

PMID: 35276521
DOI: 10.1016/j.jcis.2022.03.009

Abstract

The electronic and catalytic properties of Janus bismuth oxyhalide (Bi₂O₂XY, where X/Y = Cl, Br, or I, and X ≠ Y) for the hydrogen evolution reaction (HER) are evaluated through first-principles calculations. Janus Bi₂O₂XY shows an enhanced separation efficiency of electron-hole pairs and an augmented utilization of solar energy due to Janus asymmetry. The asymmetric halogen surfaces on both sides of Janus Bi₂O₂XY induce an electrostatic potential difference, which leads to a staggered band alignment. The solar-to-hydrogen (STH) efficiencies of Janus Bi₂O₂BrI and Bi₂O₂ClI have greatly improved compared to those of pristine BiOBr and BiOCl. Additionally, Janus Bi₂O₂XY achieves stronger internal electric fields (IEFs) and a more suitable Gibbs free energy of hydrogen adsorption (ΔG_H) than pristine BiOX. Moreover, the halogen layer with a smaller electronegativity in Janus Bi₂O₂XY forms a stronger IEF with the oxygen layer; consequently, the ΔG_H of terminations value is closer to the ideal value for the HER. The localized edge states in the p-orbital density of states (DOS) projected onto O atoms are responsible for the HER activity of terminations. This work provides a comprehensive understanding of Janus Bi₂O₂XY for the HER and provides a strategy for improving photocatalysis.

Keywords: First-principles; Gibbs free energy; Hydrogen evolution reaction; Internal electric field; Janus bismuth oxyhalides.