Unveiling Fast Charge Transfer Dynamics at Semiconductor/Electrocatalyst/Electrolyte Dual Interfaces via Boron Engineering for Efficient Water Splitting

Promoting the generation of highly active species at semiconductor/electrocatalyst/electrolyte interfaces can enhance photoelectrochemical (PEC) water splitting performance, yet achieving this goal remains challenging with current strategies. Herein, a feasible boron (B) engineering strategy is proposed to simultaneously modulate interface charge transfer and surface catalytic reaction dynamics by incorporating electron-deficient B into a state-of-the-art semiconductor/electrocatalyst system (BiVO₄/FeNiOOH). Scanning photoelectrochemical microscopy and X-ray photoelectron spectroscopy reveal that the introduction of B into FeNiOOH facilitates internal charge transfer (electrons migrate along the direction of Ni→B→Fe) via a charge relay effect, and generates more active species (Fe^3-δ and Ni^3+δ) at the BiVO₄/FeNiOOH-B/electrolyte interface, thereby accelerating both charge transfer and surface reaction dynamics. As anticipated, the BiVO₄/FeNiOOH-B photoanode achieves a remarkable photocurrent density of 6.58 mA cm⁻² at 1.23 V_RHE, along with excellent photostability. Furthermore, this B-engineering effect can be applied to develop alternative TiO₂/FeNiOOH-B configurations to further enhance PEC activity. This work opens new possibilities for B engineering in semiconductor/electrocatalyst systems, enabling highly efficient and stable water-splitting applications.