Photoelectrochemical properties of CuCr[O.sub.2]: characterization of light absorption and photocatalytic [H.sub.2] production performance

CuCr[O.sub.2] delafossite was prepared by the solid-state reaction between [Cr.sub.2][O.sub.3] and [Cu.sub.2]O at high temperature (900-1100°C). The materials were characterized by XRD, X-ray photoelectron, Raman and UV-Vis spectroscopy and transmission electron microscopy. The visible light absorption of the p-type semiconductor increased with increasing calcination temperature. First principles density functional theory calculations were used to compute the density of states and distinguish between [Cr.sup.3+] d-d transitions and the charge separation electron transitions, which cannot be distinguished in CuCr[O.sub.2] by UV-Vis spectroscopy. Photocathodes were prepared by depositing the as prepared CuCr[O.sub.2] on an FTO substrate by electrophoresis. The resulting cathodic photocurrents under visible light irradiation increased with increasing calcination temperature. CuCr[O.sub.2] is a photostable semiconductor unlike [Cu.sub.2]O. Photocatalytic [H.sub.2] production in ethanol/water mixtures shows that the resulting materials are active in water splitting. Co-catalysts substantially increase the activity, the most preferred one is Pt with an order of magnitude increase in performance.