Efficient photocatalytic CO2 reduction in all-inorganic aqueous environment: Cooperation between reaction medium and Cd(II) modified colloidal ZnS

Although photocatalytic CO2 reduction has been investigated extensively, veritably efficient "CO2 photoconverter" that can be in particular operated at all-inorganic reaction system with good durability is very few. Herein, we show that photocatalytic CO2 reduction rate over colloidal ZnS in all-inorganic aqueous environment can be improved by 1-2 orders of magnitude and reach exceptional performance after continuous regulation of reaction medium and grafting efficient cocatalysts. In the optimized condition, Cd2+ modified colloidal ZnS exhibited 95% HCOOH selectivity with 76% apparent quantum efficiency (280 nm). A modulated reaction medium maximizes the concentration of active reaction species and maintains efficient and stable photocatalytic reaction rate, while the cocatalyst significantly improves the separation of photo-excited carriers and CO2 reduction rate with targeted product selectivity. The present reaction system is much superior over the widely used inorganic reaction system with low CO2 conversion ability and organic complex photocatalysts with respect to long term reaction durability.