Non-stoichiometric Ag-In-S quantum dots for efficient photocatalytic CO2 reduction: Ag/In molar ratio dependent activity and selectivity

Abstract

Photocatalytic reduction of CO2 to syngas is a desirable strategy for recycling CO2 into valuable products, meeting energy demands in a sustainable way. Herein, we report the use of non-stoichiometric Ag-In-S quantum dots (QDs) as highly efficient and robust photocatalysts for visible-light-driven photocatalytic reduction of CO2 to syngas at atmospheric pressure and room temperature. The introduction of Co(bpy)32+ (bpy = 2′2-bipyridine) cocatalyst can promote the conversion of CO2 to CO reaction and meanwhile improve the photo-stability of Ag-In-S QDs. The photocatalytic activity and selectivity of Ag-In-S QDs are strongly dependent on the Ag to In molar ratios, and the optimized sample exhibits the highest CO evolution rate of 9.20 μmol h−1 and H2 evolution rate of 3.13 μmol h−1, corresponding to the CO selectivity of 74.61%, outperforming most of the reported QDs based photocatalysts. This work provides a new example of Cd and Pb free QDs photocatalyst for efficient and stable CO2 photoreduction.