Dual-Channel Charge Manipulation for Enhancing Charge Separation and Transfer Kinetics in BiVO ₄ Photoanodes

This work presents a synergistic dual-modification strategy to engineer distinct pathways for electrons and holes. Terbium (Tb) doping establishes a bulk ″electron highway″ within BiVO4, enhancing charge separation efficiency. Concurrently, a solution-processed high-entropy oxyhydroxide (CoFeMoCuOOH) overlayer acts as a multifunctional “hole-trapping net”, accelerating surface reaction kinetics. The modified photoanode after optimization exhibits a 6.8 mA/cm2 photocurrent density, with stable performance at 1.23 V vs RHE. The enhancement mechanism is unraveled through density functional theory (DFT) calculations and in situ Raman spectroscopy. In situ Raman spectroscopy confirms the accumulation of holes at the catalyst layer by detecting key metal-oxo (M═O) intermediates under operational conditions. DFT further verifies that Tb doping facilitates electron transport by reducing the effective electron mass, while the multimetal synergy in the high-entropy catalyst optimizes the adsorption of reaction intermediates and lowers the thermodynamic barrier of the oxygen evolution reaction. This work provides a design principle of directional charge management for advanced photoelectrodes.