Cu2O photocathodes prepared by thermal reduction of CuO: Influence of O2 concentration on photocurrent stability

Abstract

Copper oxide (CuO and Cu2O) p-type semiconducting photocathodes have gained attention for hydrogen production (proton reduction), due to their appropriate conduction band potentials and light sensitivity in the visible. However, photocorrosion is the main handicap for both compounds. In this work, the transformation of CuO layers deposited via spray pyrolysis on conductive FTO (fluorine doped tin oxide on glass) into Cu2O via thermal reduction was studied. Optimal conditions for obtaining Cu2O were found by in situ temperature-controlled XRD. Synthesis of Cu2O films was finally carried out under moderate temperature and vacuum conditions (380 °C, 1·10−2 mbar). The influence of 3 different oxygen concentration in the electrolyte on the stability of the Cu2O electrodes under light and electrical bias was studied, and it was found that the O2 content had a high impact on the photoelectrochemical performance of Cu2O electrodes. The stability of the electrodes against self-reduction was demonstrated.