FeOOH Cocatalysts with Gradient Oxygen Vacancy Distribution Enabling Efficient and Stable BiVO₄ Photoanodes

Area of Science:

• Materials Science
• Electrochemistry
• Photocatalysis

Background:

• Highly active and stable cocatalysts are crucial for efficient bismuth vanadate (BiVO4) photoanodes.
• Thick iron oxyhydroxide (FeOOH) cocatalysts, while stable, exhibit poor hole transport, limiting photoanode performance.

Purpose of the Study:

• To enhance the performance of BiVO4 photoanodes by improving hole transport in FeOOH cocatalysts.
• To introduce gradient oxygen vacancies (GOv) in FeOOH layers using a simple photoetching strategy.

Main Methods:

• Fabrication of BiVO4 photoanodes with thick FeOOH cocatalysts.
• Application of a photoetching strategy to introduce gradient oxygen vacancies (GOv) into the FeOOH layer.
• Characterization of the structural and electronic properties of the modified FeOOH layer and the photoanode.

Main Results:

• The photoetching strategy successfully introduced gradient oxygen vacancies (GOv) in the FeOOH layer.
• GOv facilitated "relay transport" of photogenerated holes and provided abundant oxidation active sites.
• The modified BiVO4/FeOOH-GOv photoanode achieved a photocurrent density of 5.37 mA cm⁻² and 160 hours of stability at 1.23 VRHE.

Conclusions:

• The developed photoetching strategy effectively optimizes FeOOH cocatalysts for enhanced photoelectrochemical water splitting.
• Gradient oxygen vacancies significantly improve hole transport dynamics and oxygen evolution reaction (OER) activity.
• This approach offers a promising pathway for constructing highly efficient and stable photoelectrochemical devices.