Catalysis of nickel ferrite for photocatalytic water oxidation using [Ru(bpy)₃]²⁺ and S₂O₈^2-

Single or mixed oxides of iron and nickel have been examined as catalysts in photocatalytic water oxidation using [Ru(bpy)₃]²⁺ as a photosensitizer and S₂O₈^2- as a sacrificial oxidant. The catalytic activity of nickel ferrite (NiFe₂O ₄) is comparable to that of a catalyst containing Ir, Ru, or Co in terms of O₂ yield and O₂ evolution rate under ambient reaction conditions. NiFe₂O₄ also possesses robustness and ferromagnetic properties, which are beneficial for easy recovery from the solution after reaction. Water oxidation catalysis achieved by a composite of earth-abundant elements will contribute to a new approach to the design of catalysts for artificial photosynthesis.