The photoelectrochemical response of the lanthanides of chromium, rhodium, vanadium and gold on a titanium base

Abstract

A number of active photo-anodes, involving lanthanum-containing compounds with chromium oxides and similar perovskitic transition metal oxides—namely, compounds involving gold, nickel, rhodium and vanadium - on a titanium base, have been studied. The electrodes were made by heating a paste of lanthanum oxide, La 2O 3, with the individual oxides of Cr 2O 3, Au 2O 3 Rh 2O 3, V 2O 3, on a titanium base. The anodic photocurrents observed were found to be 2–6 times higher than those obtained with a TiO 2 single crystal for the same intensity of the solar spectrum. The LaCrO 3TiO 2 electrode, coupled with GaP, was found to have and efficiency (overall solar spectrum) of about 2% for hydrogen evolution. This is one order of magnitude better than that for the previously examined photo-fuel cell, TiO 2GaP, and somewhat better than the for the average of the efficiencies of the values observed in natural photosynthesis. The absolute efficiency for the biased cells of LaCrO 3, LaAuO 3, LaRhO 3 and LaVaO 3 varies between 5–8% for the solar spectrum, as compared with about 1.5% for TiO 2.