Extending lifetime of photoinduced charge carriers in CuO photocathode by Zn doping for photoelectrochemical water reduction

CuO is a potential photocathode material with p-type conductivity and suitable bandgap of 1.8 ​eV. However, its energy conversion efficiency is low, which is suffered from the slow intrinsic charge transport properties. Herein, a Zn doping strategy has been proposed used to solve the above problems. For the Zn doped CuO photocathode, an increased photocurrent of −17.70 ​μA/cm2 is observed with the optimized doping amount of 0.3%. The capacitance measurements show that Zn dopant may serves as charge trapped states, which promotes more electrons accumulated on the surface of photocathode. Most importantly, the lifetime of the photoinduced charge carriers is extended, which provides more possibilities for the carriers to participate the following catalytic reaction. Density functional theory (DFT) calculations further reveal that Zn doping induced change of electronic structure, including density of state (DOS), as well as more thermos-neutral free energy of H∗ adsorption, which implies the high catalytic activity toward water reduction. [Display omitted] •Zn doped CuO photocathodes were prepared by a facile spin coating method with compact and uniform surface.•A photocurrent of −17.70 ​μA/cm2 is observed for Zn doped CuO with the optimized doping amount of 0.3%.•Zinc doping improves the charge separation efficiency and enhances the kinetics of the hydrogen evolution reaction.