Photoelectrochemical properties of LuRhO₃

Rare earth rhodates of the distorted perovskite structure are semiconductors with a band gap of 2.2 eV. They may be doped either n- or p-type. The oxides are stable against photodecomposition at the potential for hydrogen evolution. With ceramic p-type LuRhO₃ as the cathode and n-type TiO₂ as the anode of an electrolytic cell sufficient photopotential is developed both to photoelectrolyze water in sunlight with no externally applied potential and to generate power simultaneously. LuRhO₃ possesses deep lying impurity levels and surface capacitance does not exhibit ideal Mott-Schottky behavior. The Fermi level at the surface of LuRhO₃ is pinned at the same potential independent of whether the oxide is p- or n-type.