Vertically aligned Fe2TiO5 nanorods and coupling of NiMoO4/CoMoO4 as a hole-transfer cocatalyst for enhancing photoelectrochemical water oxidation performance

Abstract

Fe₂TiO₅, a promising photoanode material for photoelectrochemical (PEC) water splitting, is limited by its poor conductivity and short carrier diffusion length. Herein, a novel Fe₂TiO₅ nanorod photoanode coated with a cocatalyst NiMoO₄/CoMoO₄ has been designed for efficient PEC water splitting. The Fe₂TiO₅/NiMoO₄/CoMoO₄ photoanode shows a photocurrent density of 1.67 mA cm⁻² at 1.23 V versus the reversible hydrogen electrode (RHE) under an irradiation of 100 mW cm⁻², which is 2.25 times that of Fe₂TiO₅ nanorods (0.74 mA cm⁻²) at 1.23 V versus RHE. And the onset potential of Fe₂TiO₅/NiMoO₄/CoMoO₄ illustrates a 247 mV cathodic shift from that of the Fe₂TiO₅ nanorod photoanode. Moreover, Fe₂TiO₅/NiMoO₄/CoMoO₄ exhibits excellent stability at 1.23 V versus RHE under 2 h illumination. Further investigation indicates that NiMoO₄/CoMoO₄ modifies the surface states of Fe₂TiO₅ nanorods and effectively promotes the reaction kinetics at the semiconductor/electrolyte interface. This work emphasizes that the design of a nanorod structure and the loading of a cocatalyst provide a novel strategy for achieving excellent PEC performance.