Improved Photoelectrochemical Performance of WO₃/BiVO₄ Heterojunction Photoanodes via WO₃ Nanostructuring

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Photoelectrochemical (PEC) water splitting is crucial for producing molecular oxygen, a key step in water conversion.
• WO3/BiVO4 heterojunctions are promising photoanodes for PEC water splitting, but their performance is often limited by charge transport and recombination.

Purpose of the Study:

• To investigate the impact of nanostructuring WO3 underlayers in WO3/BiVO4 heterojunctions on PEC performance.
• To compare the PEC efficiency of nanoflake-like WO3/BiVO4 photoelectrodes with planar counterparts.

Main Methods:

• Synthesis of WO3/BiVO4 photoelectrodes with nanoflake-like and planar morphologies.
• Photoelectrochemical (PEC) testing, including measurements with a sacrificial hole scavenger.
• Electrochemical impedance analysis under simulated solar irradiation.
• Incident photon to current efficiency (IPCE) measurements.

Main Results:

• Nanostructured WO3/BiVO4 photoanodes with a nanoflake-like morphology exhibited superior PEC performance compared to planar structures.
• The nanoflake morphology effectively mitigated charge transport and charge recombination issues that plagued the planar composite.
• Enhanced charge dynamics were confirmed through impedance analysis and IPCE measurements.

Conclusions:

• Nanostructuring the WO3 underlayer into a nanoflake-like morphology is a viable strategy to enhance WO3/BiVO4 heterojunction performance in PEC water splitting.
• This nanostructuring approach overcomes kinetic bottlenecks and charge recombination limitations, paving the way for more efficient solar water splitting technologies.