Improvement of selectivity for CO2 reduction by using Cu2ZnSnS4 electrodes modified with different buffer layers (CdS and In2S3) under visible light irradiation

Abstract

Cu₂ZnSnS₄ (CZTS) electrodes modified with different n-type buffer layers (CdS and In₂S₃) were used as photocathodes for CO₂ reduction under visible light irradiation (420 < λ < 800 nm) in aqueous media. Compared to a bare CZTS electrode, CZTS electrodes modified with n-type buffer layers (CdS and In₂S₃), by which a p–n heterojunction between CZTS and the n-type buffer layer is formed, showed a significant increase in the photocurrent assigned to CO₂ reduction. In addition, product selectivity of CO₂ reduction was improved by surface modification with an n-type buffer layer: that is, selective CO₂ reduction into CO was achieved by using a CdS/CZTS electrode, while HCOOH selectivity was observed over an In₂S₃/CZTS electrode. In this study, we investigated the photoelectrochemical properties of CZTS electrodes modified with n-type buffer layers (CdS and In₂S₃) in conjunction with the structural and optical properties, and we investigated their activity for PEC CO₂ reduction.