Branch-like Cd Zn1-Se/Cu2O@Cu step-scheme heterojunction for CO2 photoreduction

The solar driven reduction of carbon dioxide (CO 2 ) to high value-added carbon based fuel is a promising solution to mitidate climate and energy problems, however, improving the adsorption and conversion efficiency of CO 2 in the photoreduction process still faces severe challenges. In this work, Cd 0·7 Zn 0·3 Se solid solution was prepared by cation exchange: selenium (Se) vacancies are produced during ion exchange, which promotes the unsaturated coordination of the surrounding metal atoms. The adsorption of diethylenetriamine (DETA) on the surface limits the growth of Cd x Zn 1- x Se crystallites, resulting in insufficient coordination of the surface atoms, which then become active adsorption sites. Furthermore, a heterojunction was formed with Cu 2 O@Cu to accelerate the separation and transfer of photo-induced carriers of Cd 0·7 Zn 0·3 Se, and the optimized Cd 0·7 Zn 0·3 Se/Cu 2 O@Cu (CZS/CC) step-scheme heterojunction exhibited a CO release activity of 50.5 μmol g −1 h −1 , which is 3.8 and 10.7 times higher than that of Cd 0·7 Zn 0·3 Se and Cu 2 O@Cu, respectively. This work is expected to open up new insight for the regulation of nanostructures and the design of selective catalysts. • Cd x Zn 1- x Se/Cu 2 O@Cu step-scheme heterostructures were fabricated. • >The heterostructures showed excellent photocatalytic CO 2 reduction activity and stability. • Step-scheme heterostructures promoted the separation of carries dramatically. • >Step-scheme electron transport effectively suppressed the photocorrosion.