A photo-active anode involving lanthanum chromite has been studied. The electrodes were made by firing lanthanum and chromium oxides, or salts which are converted upon heating to the oxide, in a paste of citric acid on a titanium oxide base. The anodic photo currents obtained were around four times greater than on an TiO2 single crystal in the same potential region on a conventional scale. The photoelectrochemical spectrum showed a pronounced and characteristic peak which differed markedly in wave length region from that on TiO2. The efficiency of conversion of solar light at a LaCrO3-TiO2 electrode is at least one order of magnitude greater than on TiO2. Hence, the situation for photo-assisted electrolysis is improved. In self-generating photo-electrolysis cells in solar light, the expected efficiency of conversion is calculated to be about one order of magnitude more than the hitherto most efficient couple, GaP-TiO2. The efficiency of hydrogen production from solar light is expected to be about 1.8% (up from 0.2175%), but the implication for the use of transition metal oxides for photo anodes is encouraging. © 1979.
