Structural Engineering of BiVO4/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 BiVO4 photoanode for boosted charge separation and transfer. The photocurrent density of the optimized BiVO4/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 BiVO4, 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 BiVO4. Transient absorption spectroscopy reveals that the CoFe MOF(NA) prolongs charge recombination lifetime by blocking the hole-transfer pathway from the BiVO4 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.

Automated summary

A structural engineering strategy is used to coat a ultrathin CoFe bimetal-organic framework (CoFe MOF) layer over a BiVO4 photoanode, resulting in boosted charge separation and transfer. The optimized BiVO4/CoFe MOF(NA) photoanode exhibits a photocurrent density of 3.92 mA cm(-2) at 1.23 V versus reversible hydrogen electrode (RHE), which is 6.03 times higher than that of pristine BiVO4, due to improved efficiency of charge transfer and separation. The CoFe MOF(NA) prolongs charge recombination lifetime and shifts the onset potential negatively, enhancing the performance of the photoanode for solar H-2 production.