Selective conversion of CO2 to CO under visible light by modulating Cd to In ratio: A case study of Cd-In-S colloidal catalysts

• Cd-In-S solid solution nanocrystals are prepared through a simple aqueous synthesis method. • Cd-In-S nanocrystals with different Cd to In ratios enable a feasible tuning of band gaps. • The optimized Cd-In-S sample shows a high CO evolution rate under visible light irradiation. • The mechanistic investigations reveal the key contributions of Cd to In molar ratio to modulate the electronic structures and charge carrier dynamics of the Cd-In-S solid solution. Developing an effective photocatalyst to promote CO 2 conversion into solar fuel is necessary for addressing the global challenge of energy sustainability and environmental problems. In this work, we report the facile fabrication of Cd-In-S (CIS) colloidal nanocrystals as an efficient visible light-responsive photocatalyst for the conversion of CO 2 to CO. Both experimental and theoretical investigations reveal the importance of Cd to In ratio which positively influences not only the charge carrier separation rate but also the electronic structure of the CIS samples. In particular, the light absorption ability, redox potential of photo-induced electrons, and charge transfer ability were effectively modulated, endowing the optimized sample with a high CO evolution rate of 22.9 µmol h -1 and selectivity up to 80% under visible light irradiation. The findings of this work can provide guidance for the design and construction of highly efficient catalytic materials for CO 2 conversion.