Electrodeposited p-type Cu2O for H2 evolution from photoelectrolysis of water under visible light illumination

Electrochemical deposition of p-type Cu2O films on transparent conducting glass from a Cu2SO4 solution was conducted at different temperatures. The films were examined for H2 evolution from photoelectrolysis of water under visible light illumination. Using Pt as the counter electrode, photocurrents with corresponding H2 evolution could be observed for the deposited Cu2O films in a Na2SO4 solution under a cathodic bias. The Cu2O films obtained at different deposition temperatures were in the cubic phase, but showed different out-of-plane crystalline orientations. An incident monochromatic photon-to-current conversion efficiency of 26% at 400 nm was achieved for a Cu2O film with a [1 1 1] out-of-plane orientation, while an efficiency of only 17% was obtained for a film with a [1 1 0] orientation. The [1 1 1]-oriented film exhibited a higher electronic conductivity, which might have led to a higher charge delocalization rate. By coupling with an n-type WO3 film to promote charge transport, the photocurrent for the Cu2O films was significantly improved.