Interfacial modulation of BiVO4 photoanodes with SnO2 quantum dots and FeOOH for efficient solar-driven water oxidation

Abstract

Addressing the global energy crisis, photoelectrochemical water splitting offers a sustainable route for solar-to-hydrogen conversion. Herein, we present a BiVO₄-based photoanode synergistically modified with (tin dioxide) SnO₂ quantum dots (QDs) and a FeOOH cocatalyst to overcome efficiency-limiting bottlenecks. The optimized BiVO₄/SnO₂ QD/FeOOH system achieves a photocurrent density of 3.92 mA cm⁻² at 1.23 V_RHE under AM1.5G, marking a 2.46-fold enhancement over pristine BiVO₄, coupled with a 140 mV cathodic shift. In situ XPS and theoretical calculations reveal that a built-in electric field forms between BiVO₄ and SnO₂ QDs. This field drives hole accumulation at the BiVO₄ interface near the SnO₂ QDs, thereby enhancing the surface photovoltage. These findings offer insights into improving the utilization efficiency of hole carriers at the photoanode surface, significantly enhancing charge separation and transfer. First-principles calculations show that SnO₂ QD incorporation induces interfacial charge redistribution and enhances the electronic conductivity in BiVO₄. Furthermore, the FeOOH overlayer, as demonstrated in recent studies, simultaneously enhances charge transfer kinetics, mitigates surface corrosion, and accelerates the oxygen evolution reaction. This dual-functional interfacial engineering strategy integrates quantum dot-mediated electronic modulation with catalytic surface activation, addressing critical challenges of charge recombination and sluggish water oxidation in BiVO₄. The work establishes a rational co-modification paradigm for developing robust semiconductor photoelectrodes, emphasizing interfacial defect control and catalytic synergy for efficient solar energy conversion.