BiNV bond: A hole-transfer bridge for high-efficient separation and transfer of carriers.

Addressing the inherent holes transport limitation of BiVO photoanode is crucial to achieve efficient photoelectrochemical (PEC) water splitting. The construction of the hole-transfer bridge between co-catalysts and BiVO photoanode could be an effective way to overcome sluggish hole-transfer kinetics of BiVO photoanode. Herein, CN/BiVO photoanode was prepared by coupling carbon nitride hydrogel (CNH) containing unsaturated N on the BiVO photoanode during annealing. CN/BiVO photoanode exhibited excellent PEC performance and stability. Photoelectrochemical tests proved that the coupling of CN accelerated holes transfer and enhanced oxygen evolution kinetics. X-ray photoelectron spectroscopy (XPS) and theoretical calculations confirmed the existence of the BiNV bond between BiVO photoanode and CN, which could serve as the hole-transfer bridge to significantly accelerate separation and transfer of carriers driven by the interfacial electric field. Moreover, it was found that the coupling of CN effectively inhibited the dissociation of metal ions through changing their coordination environment, resulting in the excellent stability of CN/BiVO photoanode. This result provides unique insights into vital roles of the interfacial structure, which might have a significant impact on the construction of PEC devices.