MXene-derived TiO2 coupled with Fe-doped perovskite fluoride for efficient photo-assisted electrocatalytic oxygen evolution and overall water splitting

Abstract

ABF₃-type perovskite fluorides have emerged as a promising platform for the oxygen evolution reaction (OER), owing to their tunable A/B sites and unique F⁻ induced electronic effects. However, the inherent low electrical conductivity and narrow light absorption range of perovskite fluorides pose significant challenges for achieving efficient and stable photo-assisted electrochemical water splitting. Herein, a three-level heterostructure of "conductive skeleton-photosensitive shell-active core" comprising iron-doped perovskite fluoride (KNi_1-xFe_xF₃) hollow nanocubes and partially oxidized Ti₃C₂ MXene (MXene@TiO₂) matrix was rationally designed via a hydrothermal strategy. The conductive MXene skeleton facilitates efficient electron transfer, while the in situ derived TiO₂ nanoparticles function as photoactive centers to promote photogenerated electron transfer, thereby boosting the catalytic OER process. Concurrently, Fe doping effectively modulates the electronic structure of KNiF₃, further optimizing its intrinsic activity. The designed MXene@TiO₂-KNi_1-xFe_xF₃ composites enable excellent OER performance in alkaline solution, requiring an overpotential of merely 199 mV to achieve 10 mA cm⁻². Notably, for overall water splitting (OWS), the assembled electrolyzer delivers a current density of 20 mA cm⁻² at a low overpotential of 266 mV. Furthermore, the electrocatalyst delivers exceptional durability, sustaining over 90 h of continuous operation for both OER and OWS. Under AM 1.5 G simulated sunlight, the photocurrent density is significantly enhanced, underscoring the composite's potential in solar-energy-assisted water electrolysis. This work not only offers a strategic design for MXene-perovskite hybrids but also paves the way for developing highly efficient and stable solar-driven electrochemical systems.