Structural Engineering of BiVO₄ /CoFe MOF Heterostructures Boosting Charge Transfer for Efficient...

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Efficient photoelectrochemical (PEC) hydrogen generation relies on effective charge separation and transfer in photoanodes.
• Bismuth vanate (BiVO4) is a promising photoanode material, but its performance is limited by charge recombination.

Purpose of the Study:

• To enhance charge separation and transfer in BiVO4 photoanodes for improved PEC hydrogen production.
• To investigate the effect of a uniformly coated ultrathin CoFe bimetal-organic framework (CoFe MOF) layer on BiVO4 performance.

Main Methods:

• Structural engineering by uniformly coating an ultrathin CoFe MOF layer over a BiVO4 photoanode.
• Photoelectrochemical testing to measure photocurrent density and onset potential.
• Transient absorption spectroscopy to analyze charge dynamics and recombination pathways.

Main Results:

• The optimized BiVO4/CoFe MOF(NA) photoanode achieved a photocurrent density of 3.92 mA cm⁻² at 1.23 V vs RHE, a 6.03-fold increase compared to pristine BiVO4.
• A significant negative shift in onset potential was observed for the modified photoanode.
• Transient absorption spectroscopy indicated that CoFe MOF(NA) prolongs charge recombination lifetime by blocking hole transfer to trap states.

Conclusions:

• Uniformly coating an ultrathin CoFe MOF layer on BiVO4 photoanodes is an effective strategy for boosting charge separation and transfer.
• This structural engineering approach significantly enhances photocurrent density for solar hydrogen production.
• The findings provide insights into improving photoanode performance for efficient solar fuel generation.