Dual Mo-Doping in BiVO₄/FeCoNiO_x Photoanode Enables Near-Theoretical Photocurrent Density via Synergistic...

Bismuth vanadate (BiVO₄) is an auspicious photoanode material for photoelectrochemical (PEC) water splitting, but its performance is fundamentally limited by severe charge recombination and sluggish kinetics of the oxygen evolution reaction (OER). Herein, a dual electronic modulation strategy is developed by incorporating molybdenum (Mo) dopants simultaneously into the FeCoNiO_x cocatalyst surface and the bulk phase of BiVO₄. The resulting Mo:FeCoNiO_x/Mo:BiVO₄ photoanode delivers a near-theoretical photocurrent density of 7.15 mA cm⁻² at 1.23 V versus reversible hydrogen electrode (RHE) under AM 1.5 G illumination. This exceptional performance arises from the Mo-triggered cross-scale electronic reconstruction: (1) In the bulk, Mo substitution at vanadium (V) sites in BiVO₄ enhances charge transport via n-type doping; (2) At the surface, Mo incorporation into FeCoNiO_x triggers electron redistribution, creating localized electron reservoirs at Fe/Co/Ni sites. Combined density functional theory (DFT) calculations and experimental validation reveal that the reconfigured Fe sites serve a dual function as efficient hole traps and highly active OER centers, reducing the reaction energy barrier (ΔG_*OH) by 1.26 eV. Moreover, the optimized interfacial charge transport boosts carrier separation efficiency from 84.9% to 96.5% and accelerates hole migration by 2.7-fold compared to pristine BiVO₄. This work provides insights into multi-scale electronic engineering for solar energy conversion.