Mechanistic Insights into Enhanced Hydrogen Evolution of CrOx /Rh Nanoparticles for Photocatalytic Water Splitting

Tomohiro Higashi; Kazuhiko Seki; Yutaka Sasaki; Yuriy Pihosh; Vikas Nandal; Mamiko Nakabayashi; Naoya Shibata; Kazunari Domen

doi:10.1002/chem.202204058

Mechanistic Insights into Enhanced Hydrogen Evolution of CrO_x /Rh Nanoparticles for Photocatalytic Water Splitting

Chemistry. 2023 Apr 25;29(24):e202204058. doi: 10.1002/chem.202204058. Epub 2023 Mar 20.

Authors

Tomohiro Higashi¹, Kazuhiko Seki², Yutaka Sasaki³, Yuriy Pihosh³, Vikas Nandal², Mamiko Nakabayashi⁴, Naoya Shibata⁴, Kazunari Domen^{3

5}

Affiliations

¹ Institute for Tenure Track Promotion, University of Miyazaki, Nishi 1-1 Gakuen-Kibanadai, Miyazaki, 889-2192, Japan.
² Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 16-1 Onogawa, Ibaraki, 305-8569, Japan.
³ Office of University Professors, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-8656, Japan.
⁴ Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-8656, Japan.
⁵ Research Initiative for Supra-Materials (RISM), Shinshu University, 4-17-1 Wakasato, Nagano, 380-8533, Japan.

PMID: 36764932
DOI: 10.1002/chem.202204058

Abstract

The hydrogen evolution reaction (HER) of Rh nanoparticles (RhNP) coated with an ultrathin layer of Cr-oxides (CrO_x ) was investigated as a model electrode for the Cr₂ O₃ /Rh-metal core-shell-type cocatalyst system for photocatalytic water splitting. The CrO_x layer was electrodeposited over RhNP on a transparent conductive fluorine-doped tin oxide (FTO) substrate. The CrO_x layer on RhNP facilitates the electron transfer process at the CrO_x /RhNP interface, leading to the increased current density for the HER. Impedance spectroscopic analysis revealed that the CrO_x layer transferred protons via the hopping mechanism to the RhNP surface for HER. In addition, CrO_x restricted electron transfer from the FTO to the electrolyte and/or RhNP and suppressed the backward reaction by limiting oxygen migration. This study clarifies the crucial role of the ultrathin CrO_x layer on nanoparticulate cocatalysts and provides a cocatalyst design strategy for realizing efficient photocatalytic water splitting.

Keywords: chromium oxide; electrocatalyst; hydrogen evolution; photocatalyst; rhodium nanoparticle.

Abstract

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