Environmentally friendly Cu2ZnSnS4-based photocathode modified with a ZnS protection layer for efficient solar water splitting

Kang Wang; Dingwang Huang; Le Yu; Huaimin Gu; Shigeru Ikeda; Feng Jiang

doi:10.1016/j.jcis.2018.10.032

Environmentally friendly Cu₂ZnSnS₄-based photocathode modified with a ZnS protection layer for efficient solar water splitting

J Colloid Interface Sci. 2019 Feb 15:536:9-16. doi: 10.1016/j.jcis.2018.10.032. Epub 2018 Oct 13.

Authors

Kang Wang¹, Dingwang Huang¹, Le Yu¹, Huaimin Gu¹, Shigeru Ikeda², Feng Jiang³

Affiliations

¹ Institute of Optoelectronic Materials and Technology, South China Normal University, Guangzhou 510631, PR China.
² Department of Chemistry, Konan University, 9-1 Okamoto, Higashinada, Kobe, Hyogo 658-8501, Japan.
³ Institute of Optoelectronic Materials and Technology, South China Normal University, Guangzhou 510631, PR China. Electronic address: fengjiangsolar@126.com.

PMID: 30342410
DOI: 10.1016/j.jcis.2018.10.032

Abstract

High-quality Cu₂ZnSnS₄ (CZTS) thin films prepared by spray pyrolysis on a Mo-coated glass substrate were used for solar water splitting in this study. Modification of a CdS layer under CZTS improved the photocatalysis efficiency by forming a pn junction between CdS and CZTS, effectively separating the photoexcited carriers without recombination. However, the photocorrosive nature of CdS induces poor stability of the CdS/CZTS photocathode. Surface protection of a CdS-covered CZTS photocathode by a ZnS layer resulted in efficient photoelectrochemical water splitting with a maximum half-cell solar to hydrogen (HC-STH) efficiency of 2.1% and without showing appreciable degradation. The ZnS layer acts as a mediator for efficient electron transport to Pt deposits and as a protective layer, preventing contact between the CdS layer and the outer electrolyte solution.

Keywords: CZTS; Carrier transfer; Photoelectrochemical stability; Solar water splitting; Surface protection.