A Cocatalyst that Stabilizes a Hydride Intermediate during Photocatalytic Hydrogen Evolution over a Rhodium-Doped TiO2 Nanosheet

Shintaro Ida; Kenta Sato; Tetsuya Nagata; Hidehisa Hagiwara; Motonori Watanabe; Namhoon Kim; Yoshihito Shiota; Michio Koinuma; Sakae Takenaka; Takaaki Sakai; Elif Ertekin; Tatsumi Ishihara

doi:10.1002/anie.201803214

A Cocatalyst that Stabilizes a Hydride Intermediate during Photocatalytic Hydrogen Evolution over a Rhodium-Doped TiO₂ Nanosheet

Angew Chem Int Ed Engl. 2018 Jul 16;57(29):9073-9077. doi: 10.1002/anie.201803214. Epub 2018 Jun 19.

Authors

Shintaro Ida^{1

2}, Kenta Sato², Tetsuya Nagata¹, Hidehisa Hagiwara^{2

3}, Motonori Watanabe³, Namhoon Kim⁴, Yoshihito Shiota⁵, Michio Koinuma¹, Sakae Takenaka⁶, Takaaki Sakai², Elif Ertekin^{3

4}, Tatsumi Ishihara^{2

3}

Affiliations

¹ Department of Applied Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Chuo, Kumamoto, 860-8555, Japan.
² Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
³ International Institute for Carbon Neutral Energy Research, Kyushu University, Motooka 744, Nishi-ku, Fukuoka, 819-0395, Japan.
⁴ Department of Mechanical Science and Engineering, University of Illinois at, Urbana-Champaign, IL, USA.
⁵ Institute for Materials Chemistry and Engineering, Kyushu University, Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
⁶ Faculty of Science and Engineering, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe-shi, Kyoto, 610-0394, Japan.

PMID: 29766627
DOI: 10.1002/anie.201803214

Abstract

The hydrogen evolution reaction using semiconductor photocatalysts has been significantly improved by cocatalyst loading. However, there are still many speculations regarding the actual role of the cocatalyst. Now a photocatalytic hydrogen evolution reaction pathway is reported on a cocatalyst site using TiO₂ nanosheets doped with Rh at Ti sites as one-atom cocatalysts. A hydride species adsorbed on the one-atom Rh dopant cocatalyst site was confirmed experimentally as the intermediate state for hydrogen evolution, which was consistent with the results of density functional theory (DFT) calculations. In this system, the role of the cocatalyst in photocatalytic hydrogen evolution is related to the withdrawal of photo-excited electrons and stabilization of the hydride intermediate species; the presence of oxygen vacancies induced by Rh facilitate the withdrawal of electrons and stabilization of the hydride.

Keywords: cocatalysts; hydrogen evolution; nanosheets; photocatalysis; water splitting.