Cocatalyst engineering of a narrow bandgap Ga-La5Ti2Cu0.9Ag0.1O7S5 photocatalyst towards effectively enhanced water splitting

Qi Xiao; Jiadong Xiao; Junie Jhon M. Vequizo; Takashi Hisatomi; Mamiko Nakabayashi; Shanshan Chen; Zhenhua Pan; Lihua Lin; Naoya Shibata; Akira Yamakata; Tsuyoshi Takata; Kazunari Domen

doi:10.1039/D1TA08770C

Cocatalyst engineering of a narrow bandgap Ga-La₅Ti₂Cu_0.9Ag_0.1O₇S₅ photocatalyst towards effectively enhanced water splitting†

Qi Xiao,

^ab Jiadong Xiao,^a Junie Jhon M. Vequizo,

^a Takashi Hisatomi,

^a Mamiko Nakabayashi,^c Shanshan Chen,

^a Zhenhua Pan,

^a Lihua Lin,^a Naoya Shibata,^c Akira Yamakata,

^d Tsuyoshi Takata^a and Kazunari Domen

*^ae

Author affiliations

* Corresponding authors

^a Research Initiative for Supra-Materials, Shinshu University, 4-17-1 Wakasato, Nagano-shi, Nagano 380-8553, Japan
E-mail: domen@shinshu-u.ac.jp

^b State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China

^c Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, 113-8656 Tokyo, Japan

^d Graduate School of Engineering, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku-ku, Nagoya 468-8511, Japan

^e Office of University Professors, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan
E-mail: domen@chemsys.t.u-tokyo.ac.jp

Abstract

Ga-La₅Ti₂Cu_0.9Ag_0.1O₇S₅ (Ga-LTCA), an oxysulfide photocatalyst, can act as a hydrogen evolution photocatalyst in Z-scheme water splitting systems in conjunction with an oxygen evolution photocatalyst (OEP) under visible light irradiation up to 700 nm. However, the overall efficiency is strongly limited by the low activity of Ga-LTCA. The present work demonstrates a drastic improvement in the H₂ evolution activity of Ga-LTCA after loading small Rh cocatalyst particles exhibiting uniform dispersion and intimate contact with the photocatalyst. Using this system, an apparent quantum yield (AQY) of 11.2 ± 0.9% at 420 nm was obtained for H₂ evolution from an aqueous Na₂S–Na₂SO₃ solution, this being the highest value yet reported for a sacrificial H₂ evolution reaction using an oxysulfide photocatalyst. Following modification with a Cr₂O₃ layer, efficient Z-scheme water splitting was also accomplished using the cocatalyst-loaded Ga-LTCA in combination with H⁺/Cs⁺/PtO_x/WO₃ as the OEP, with an improved AQY of 2.4% at 420 nm.

Journal of Materials Chemistry A

Cocatalyst engineering of a narrow bandgap Ga-La₅Ti₂Cu_0.9Ag_0.1O₇S₅ photocatalyst towards effectively enhanced water splitting†

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Cocatalyst engineering of a narrow bandgap Ga-La₅Ti₂Cu_0.9Ag_0.1O₇S₅ photocatalyst towards effectively enhanced water splitting

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Journal of Materials Chemistry A