Chinese Journal of Catalysis ›› 2024, Vol. 64: 77-86.DOI: 10.1016/S1872-2067(24)60093-8

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The role of titanium at the interface of hematite photoanode in multisite mechanism: Reactive site or cocatalyst site?

Minfei Xiea,1, Xing Jib,1, Huaying Mengb,1, Nanbing Jiangb, Zhenyu Luob, Qianqian Huanga, Geng Sunb,*(), Yunhuai Zhangb,*(), Peng Xiaoa,*()   

  1. aChongqing Key Laboratory of Interface Physics in Energy Conversion, College of Physics, Chongqing University, Chongqing 401331, China
    bCollege of Chemistry and Chemical Engineering, Chongqing University, Chongqing 401331, China
  • Received:2024-03-23 Accepted:2024-07-08 Online:2024-09-18 Published:2024-09-19
  • Contact: * E-mail: sungengemail@cqu.edu.cn (G. Sun),zyh2031@cqu.edu.cn (Y. Zhang),xiaopeng@cqu.edu.cn (P. Xiao).
  • About author:1Contributed equally to this work.
  • Supported by:
    Fundamental Research Funds for the Central Universities(2022CDJQY-007);Fundamental Research Funds for the Central Universities(2022CDJJCLK001);Fundamental Research Funds for the Central Universities(2023CDJXY-046)

Abstract:

Hematite (α-Fe2O3) constitutes one of the most promising photoanode materials for oxygen evolution reaction (OER). Recent research on Fe2O3 have found a fast OER rate dependence on surface hole density, suggesting a multisite reaction pathway. However, the effect of heteroatom in Fe2O3 on the multisite mechanism is still poorly understood. Herein we synthesized Fe2O3 on Ti substrates (Fe2O3/Ti) to study the oxygen intermediates of OER by light-dark electrochemical scans. We identified the Fe-OH species disappeared and Ti-OH intermediates appeared on Fe2O3/Ti when pH = 11‒14, which significantly improved the OER performance of Fe2O3/Ti. Combined with the density functional theory calculations, we propose that Ti atom acts as cocatalyst site and captures proton from neighboring Fe-OH species under highly alkaline condition, thereby promoting the coupling of Fe=O and reducing the energy barrier of the non-electrochemical step. Our work provides a new insight into the role of heteroatom in OER multisite mechanism based on clarifying the reaction intermediates.

Key words: Hematite, Oxygen evolution reaction, Multisite mechanism, Intermediate, Proton capture