Bismuth vanadate (BiVO₄) is a promising material for photoelectrochemical (PEC) water splitting, however, its PEC performance is limited by the high surface and bulk charge recombination rates. Here we present a comprehensive study to elucidate a recombination phenomenon of BiVO₄ that arises with Mo doping. The Mo doping produces multiple effects including the formation of MoO_x (reduced form of Mo⁶⁺) species and oxygen vacancies (V_Os) on the surface of the BiVO₄ that work in tandem with V⁴⁺ species (and MoO_x) acting as surface-active intermediates (i-SS) providing improved hole transfer to the electrolyte. In contrast, in the absence of V⁴⁺ species, the V_Os can act as recombination centers (r-SS). Further, CoOOH co-catalyst coating is used to minimize such recombination centers. Eventually, a photocurrent enhancement of ~37 times (1.1 mA/cm² at 1.23 V vs. RHE) and a cathodic shift in onset potential of ~500 mV compared to that of pristine BiVO₄ (0.03 mA/cm² at 1.23 V vs. RHE) is obtained. We carried out in-depth PEC analysis using hole scavenger measurements, PEC impedance spectroscopy, and intensity-modulated photocurrent spectroscopy to elucidate the effect of the surface reduction process upon doping, the impact of Vos, MoO_x species and CoOOH layer on the enhanced PEC performance.

钒酸铋（BiVO ₄）是用于光电化学（PEC）水分解的一种有前途的材料，但是，其PEC性能受到高表面电荷和大量电荷复合率的限制。在这里，我们提出了一项全面的研究，以阐明Mo掺杂引起的BiVO ₄的重组现象。Mo掺杂产生多种效应，包括形成MoO _x（Mo ^6+的还原形式）和BiVO ₄表面上与V ⁴⁺物种（和MoO _x）协同作用的氧空位（V _O s）。作为表面活性中间体（异SS）改善了空穴向电解质的转移。与此相反，在不存在第V ⁴⁺物种中，V _ø S可充当复合中心（ř -SS）。此外，使用CoOOH助催化剂涂层来最小化这种复合中心。最终，与原始BiVO ₄相比，光电流提高了约37倍（1.23 V时相对于RHE为1.1 mA / cm ²），起始电位的阴极位移为约500 mV（相对于1.23 V时为0.03 mA / cm ²。 （RHE）。我们使用空穴清除剂测量，PEC阻抗谱和强度调制光电流谱进行了深入的PEC分析，以阐明表面还原工艺对掺杂的影响，Vos，MoO的影响_x物种和CoOOH层增强了PEC性能。