Stabilizing CuGaS2 by crystalline CdS through an interfacial Z-scheme charge transfer for enhanced photocatalytic CO2 reduction under visible light

Abstract

CuGaS₂ is one of the most excellent visible-light-active photocatalysts for CO₂ reduction and water splitting. However, CuGaS₂ suffers from serious deactivation in photocatalytic reactions, which is mainly due to the photo-oxidation induced self-corrosion (Cu⁺ to Cu²⁺). Here, we constructed a CuGaS₂/CdS hybrid photocatalyst dominated by a Z-scheme charge transfer mechanism. The transfer of photo-generated electrons from excited nanocrystalline CdS to CuGaS₂ across the coherent interface reduces Cu²⁺ formation and favors Cu⁺ regeneration. This process suppresses the deactivation of CuGaS₂ and maintains high performance. Both the activity and stability of photocatalytic CO₂ reduction to produce CO over the CuGaS₂/CdS hybrid were remarkably improved, which was approximately 4-fold higher than CuGaS₂ and 3-fold higher than CdS in converting CO₂ into CO. Our study demonstrates that even using the semiconductors prone to photo-corrosion, it is possible to obtain satisfactory catalytic activity and stability by designing efficient Z-scheme-charge-transfer-type photocatalysts.