Structural Engineering of BiVO 4 /CoFe MOF Heterostructures Boosting Charge Transfer for Efficient Photoelectrochemical Water Splitting.

Boosting charge separation and transfer of photoanodes is crucial for providing high viability of photoelectrochemical hydrogen (H 2 ) generation. Here, a structural engineering strategy is designed and synthesized for uniformly coating an ultrathin CoFe bimetal-organic framework (CoFe MOF) layer over a BiVO 4 photoanode for boosted charge separation and transfer. The photocurrent density of the optimized BiVO 4 /CoFe MOF(NA) photoanode reaches a value of 3.92 mA cm -2 at 1.23 V versus reversible hydrogen electrode (RHE), up to 6.03 times that of pristine BiVO 4 , due to the greatly increased efficiency of charge transfer and separation. In addition, this photoanode records one onset potential that is considerably shifted negatively when compared to BiVO 4 . Transient absorption spectroscopy reveals that the CoFe MOF(NA) prolongs charge recombination lifetime by blocking the hole-transfer pathway from the BiVO 4 to its surface trap states. This work sheds light on boosting charge separation and transfer through structural engineering to enhance the photocurrent of photoanodes for solar H 2 production.