MXene-modified BiVO₄/FePO₄ photoanodes for solar oxygen evolution

Photoelectrochemical reactions in aqueous systems represent a promising route for solar fuel production; however, their efficiency is often constrained by the sluggish kinetics of the anodic oxygen evolution reaction (OER). BiVO₄ is one of the most promising photoanode materials and has demonstrated the ability to efficiently convert light into electrical and then chemical energy. However, the conversion efficiency of pure BiVO₄ remains insufficient. In this work, BiVO₄ photoanodes are first modified with FePO₄ using a simple Autodrop process and subsequently integrated with Ti₃C₂T _x MXene overlayers deposited via automated spray coating. The thus modified photoanodes exhibit a superior performance thanks to the synergistic interaction between the FePO₄ and MXene layers, which promotes the movement of electrons and efficient charge separation, thus suppressing surface recombination in BiVO₄. Meanwhile, both the FePO₄ and MXene layers can act as hole-transport channels and co-catalytic interfaces, facilitating interfacial charge transfer and accelerating OER kinetics. Importantly, achieving an optimal balance between MXene coverage and FePO₄ exposure is critical to maximizing catalytic activity within the BiVO₄/FePO₄/MXene heterostructure. By optimizing the MXene loading, the modified BiVO₄/FePO₄ photoelectrode exhibits an approximately 50% improvement in photocurrent performance. Overall, this work presents a simple and effective strategy for fabricating high-performance photoanodes with potential for scalable production. The proposed heterojunction design provides a promising pathway toward the development of efficient and stable photoanodes for solar fuel applications.