Binary Transition Metal NiFeO_x and CoFeO_x Cocatalysts Boost the Photodriven Water Oxidation over Fe₂TiO₅ Nanoparticles

Abstract Although achieving a perfect match between a cocatalyst and a photocatalyst is challenging, it is a key factor to maximize the production of solar fuels. Herein, the nanostructured binary transition metal oxides NiFeO_x and CoFeO_x, loaded through magnetron sputtering deposition, were employed as cocatalysts for Fe₂TiO₅ nanoparticles, applied to the oxygen production from solar water splitting. After the coverage of Fe₂TiO₅ with exceptionally small CoFeO_x and NiFeO_x nanoparticles, the O₂ evolution boosted from 7.0 (pure Fe₂TiO₅) to 56.0 and 63.0 μmol, respectively, under visible light irradiation. To the best of our knowledge, these performance enhancements are the highest reported for the particulate Fe₂TiO₅ photocatalyst, so far. The improvements result from the alleviation of charge transfer resistance at the solid/liquid interface, as the binary metal oxides aid the charge carriers separation at the heterojunctions and improve the kinetics of the water oxidation reaction.