High-efficiency photoelectrocatalytic oxygen evolution reaction enabled by MXene-derived TiO2 coupled with FeP nanoparticles

Abstract

When two-dimensional MXene derivatives couple with electroactive agents, their photo-assisted effects can facilitate charge separation and transport. In this work, a heterostructure of MXene-derived TiO₂ coupled with FeP nanoparticles (MXene@TiO₂/FeP) for the photoelectrocatalytic oxygen evolution reaction (OER) was successfully designed via pre-oxidation and phosphorization processes. Due to the high specific surface area of MXene and the highly dispersed active species (FeP), the constructed MXene@TiO₂/FeP inherits excellent electrocatalytic performance. The catalyst has an overpotential of only 240 mV at a current density of 10 mA cm⁻² and a long-term stability of more than 100 h, which is superior to numerous reported MXene-based electrocatalysts. Importantly, MXene@TiO₂/FeP enables remarkable photoelectrocatalytic OER activity. Under light conditions, the overpotential is reduced by 31 mV and 43 mV at current densities of 20 mA cm⁻² and 50 mA cm⁻², respectively. The photocurrent transient response further confirms the enhanced photoluminescence charge transfer and energy band separation upon integration of TiO₂ with FeP. Experimental results reveal that MXene@TiO₂ captures photogenerated holes, inhibits charge complexation and promotes charge transfer to FeP, thereby accelerating OER kinetics. This work elaborates the significance of MXene derivatives as effective photoanodes to enhance water splitting, which highlights their potential to address the problem of hydrogen production.