Synergistic Engineering of Electron Structure and Interface in BiVO₄ Photoelectrodes for Efficient PEC Water...

BiVO₄ shows promising application prospects for photoelectrochemical (PEC) devices such as water splitting and self-powered photodetectors, but several bottlenecks still remain, including severe charge recombination effects and slow oxygen evolution reaction (OER) kinetics. We proposed a strategy to address the above issues by introducing Mo doping combined with the use of NiFeOOH as a cocatalyst. Mo doping can modulate the BiVO₄ particle size and enrich the reactive surface area to enhance light absorption and the OER. Besides, Mo doping not only improves the conductivity and charge carrier concentration of the BiVO₄ photoanode but also causes low Fermi energy level and large energy band bending, thereby accelerating surface charge transfer. Moreover, the NiFeOOH cocatalyst electrodeposited on Mo-doped BiVO₄ can passivate the surface defect state and avoid hole accumulation. In the meantime, the increased oxygen vacancies induced by Mo doping and the presence of NiFeOOH collectively enhance the kinetics of the OER kinetics. Benefiting from the above combined effects, the synergistic integration of Mo and NiFeOOH effectively suppresses charge recombination while promoting electron extraction and hole injection. As a result, the obtained photoanode shows a photocurrent density of 2.24 mA/cm² at 1.23 V versus RHE, approximately 2.52-fold higher than that of pristine BiVO₄ photoanode. Furthermore, the as-prepared photodetector demonstrates excellent photodetection performance with high responsivity (R_ph, 31.06 mA/W), superior detectivity (D*, 2.02 × 10¹¹ Jones), and large external quantum efficiency (EQE, 7.7%) in the Na₂SO₄ electrolyte under 488 nm with zero bias voltage. This work contributes to the development of multifunctional strategies for enhancing the charge transport properties of PEC devices.