(A) Photoelectrochemical overall water splitting over BiVO4 thin film electrode and (B) stability of photocurrent using BiVO4 thin film electrode and Pt counter under visible light irradiation. Dashed line: the half of the amount of electron, open square: the rate of H2 evolution. Preparation condition, calcined at 673 K for 2 h. Electrolyte, 0.1 mmol L-1 of an aqueous K2SO4 solution; potential, 1 V vs. Ag/AgCl; electrode area, 1.5 cm2; light source, 300 W Xe-lamp with a cut-off filter (λ > 420 nm).