Ru-P pair sites boost charge transport in hematite photoanodes for exceeding 1% efficient solar water splitting

Rui-Ting Gao; Lijia Liu; Yanbo Li; Yang Yang; Jinlu He; Xianhu Liu; Xueyuan Zhang; Lei Wang; Limin Wu

doi:10.1073/pnas.2300493120

Ru-P pair sites boost charge transport in hematite photoanodes for exceeding 1% efficient solar water splitting

Proc Natl Acad Sci U S A. 2023 Jul 4;120(27):e2300493120. doi: 10.1073/pnas.2300493120. Epub 2023 Jun 26.

Authors

Rui-Ting Gao¹, Lijia Liu², Yanbo Li³, Yang Yang^{4

5

6

7

8}, Jinlu He¹, Xianhu Liu⁹, Xueyuan Zhang¹⁰, Lei Wang¹, Limin Wu^{1

11}

Affiliations

¹ College of Chemistry and Chemical Engineering, College of Energy Material and Chemistry, Inner Mongolia University, 010021 Hohhot, China.
² Department of Chemistry, Western University, London, ON N6A5B7, Canada.
³ Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, 610054 Chengdu, China.
⁴ NanoScience Technology Center, University of Central Florida, Orlando, FL 32826.
⁵ Department of Materials Science and Engineering, University of Central Florida, Orlando, FL 32826.
⁶ Department of Chemistry, University of Central Florida, Orlando, FL 32826.
⁷ Renewable Energy and Chemical Transformation Cluster, University of Central Florida, Orlando, FL 32826.
⁸ The Stephen W. Hawking Center for Microgravity Research and Education, University of Central Florida, Orlando, FL 32826.
⁹ Key Laboratory of Materials Processing and Mold, Ministry of Education, Zhengzhou University, 450002 Zhengzhou, China.
¹⁰ School of Materials Science and Engineering, China University of Petroleum (East China), 266580 Qingdao, China.
¹¹ Department of Materials Science and State Key Laboratory of Molecular Engineering of Polymers, Fudan University, 200433 Shanghai, China.

Abstract

Fast transport of charge carriers in semiconductor photoelectrodes are a major determinant of the solar-to-hydrogen efficiency for photoelectrochemical (PEC) water slitting. While doping metal ions as single atoms/clusters in photoelectrodes has been popularly used to regulate their charge transport, PEC performances are often low due to the limited charge mobility and severe charge recombination. Here, we disperse Ru and P diatomic sites onto hematite (DASs Ru-P:Fe₂O₃) to construct an efficient photoelectrode inspired by the concept of correlated single-atom engineering. The resultant photoanode shows superior photocurrent densities of 4.55 and 6.5 mA cm^-2 at 1.23 and 1.50 V_RHE, a low-onset potential of 0.58 V_RHE, and a high applied bias photon-to-current conversion efficiency of 1.00% under one sun illumination, which are much better than the pristine Fe₂O₃. A detailed dynamic analysis reveals that a remarkable synergetic ineraction of the reduced recombination by a low Ru doping concentration with substitution of Fe site as well as the construction of Ru-P bonds in the material increases the carrier separation and fast charge transportation dynamics. A systematic simulation study further proves the superiority of the Ru-P bonds compared to the Ru-O bonds, which allows more long-lived carriers to participate in the water oxidation reaction. This work offers an effective strategy for enhancing charge carrier transportation dynamics by constructing pair sites into semiconductors, which may be extended to other photoelectrodes for solar water splitting.

Keywords: charge carrier transfer; electron-hole recombination; hematite photoelectrodes; metal and nonmetal pair sites; photoelectrochemical water oxidation.