Photocatalytic and Photoelectrochemical Hydrogen Evolution from Water over Cu2SnxGe1- xS3 Particles

Yosuke Kageshima; Sota Shiga; Tatsuki Ode; Fumiaki Takagi; Hiromasa Shiiba; Myo Than Htay; Yoshio Hashimoto; Katsuya Teshima; Kazunari Domen; Hiromasa Nishikiori

doi:10.1021/jacs.0c12140

Photocatalytic and Photoelectrochemical Hydrogen Evolution from Water over Cu₂Sn_xGe_{1- x}S₃ Particles

J Am Chem Soc. 2021 Apr 21;143(15):5698-5708. doi: 10.1021/jacs.0c12140. Epub 2021 Apr 7.

Authors

Yosuke Kageshima^{1

2}, Sota Shiga¹, Tatsuki Ode¹, Fumiaki Takagi¹, Hiromasa Shiiba², Myo Than Htay^{2

3}, Yoshio Hashimoto^{2

3}, Katsuya Teshima^{1

2}, Kazunari Domen^{2

4}, Hiromasa Nishikiori^{1

2}

Affiliations

¹ Department of Materials Chemistry, Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan.
² Research Initiative for Supra-Materials (RISM), Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan.
³ Department of Electrical and Computer Engineering, Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan.
⁴ Department of Chemical System Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.

PMID: 33827207
DOI: 10.1021/jacs.0c12140

Abstract

Cu₂Sn_xGe_1-xS₃ (CTGS) particles were synthesized via a solid-state reaction and assessed, for the first time, as both photocatalysts and photocathode materials for hydrogen evolution from water. Variations in the crystal and electronic structure with the Sn/Ge ratio were examined experimentally and theoretically. The incorporation of Ge was found to negatively shift the conduction band minimum, such that the bandgap energy could be tuned over the range 0.77-1.49 eV, and also increased the driving force for the photoexcited electrons involved in hydrogen evolution. The effects of the Sn/Ge ratio and of Cu deficiency on the photoelectrochemical performance of Cu₂Sn_xGe_1-xS₃ and Cu_ySn_0.38Ge_0.62S₃ (1.86 < y < 2.1) based photocathodes were evaluated under simulated sunlight. Both variations in the band-edge position and the presence of a secondary impurity phase affected the performance, such that a particulate Cu_1.9Sn_0.38Ge_0.62S₃ photocathode was the highest performing specimen. This cathode gave a half-cell solar-to-hydrogen energy conversion efficiency of 0.56% at 0.18 V vs a reversible hydrogen electrode (RHE) and an incident-photon-to-current conversion efficiency of 18% in response to 550 nm monochromatic light at 0 V_RHE. More importantly, these CTGS particles also demonstrated significant photocatalytic activity during hydrogen evolution and were responsive to radiation up to 1500 nm, representing infrared light. The chemical stability, lack of toxicity, and high activity during hydrogen evolution of the present CTGS particles suggest that they may be potential alternatives to visible/infrared light responsive Cu-chalcogenide photocatalysts and photocathode materials such as Cu(In,Ga)(S,Se)₂ and Cu₂ZnSnS₄.