Construction of atomically dispersed Cu sites and S vacancies on CdS for enhanced photocatalytic CO2 reduction

The controllable introduction of anion vacancies (such as O vacancies and S vacancies) or atomically dispersed metal sites in semiconductors is a promising strategy to improve photocatalytic performance. However, the facile construction of a photocatalyst containing two types of potential active sites simultaneously is still challenging. Herein, we adopt a facile cation exchange strategy to create atomically dispersed Cu sites and accompanying sulfur vacancies on the CdS surface for photocatalytic CO2 reduction. The fabricated CuCdS-5 sample exhibits 3 times improvement in CO yield with a selectivity of 92% in comparison to original CdS. Experimental analysis and DFT calculations reveal that the atomically dispersed Cu sites and S vacancies provide additional CO2 adsorption sites, redistribute the local charges and lower the dissociative adsorption energy of CO2, which enhance the photocatalytic activity. Our work provides a new perspective to design semiconductors with engineered active sites for efficient photocatalytic CO2 reduction.