Addressing phase instability and charge recombination in pyrolysis-synthesized BiVO₄ via DFT-guided Mo doping for...

Area of Science:

• Materials Science
• Photocatalysis
• Renewable Energy

Background:

• Transparent bismuth vanadate (BiVO4) photoanodes are crucial for solar-to-chemical energy conversion.
• Current MOD methods suffer from charge recombination and phase instability, limiting BiVO4 application.
• Developing stable and efficient BiVO4 photoanodes is essential for advancing solar fuel production.

Purpose of the Study:

• To identify effective dopants for improving BiVO4 photoanode performance using DFT calculations.
• To experimentally validate the role of dopants in enhancing charge transport and phase stability.
• To achieve high solar-to-hydrogen (STH) efficiency in a tandem water-splitting device.

Main Methods:

• Density functional theory (DFT) calculations for dopant screening.
• Metal-organic decomposition (MOD) method for synthesizing doped BiVO4 films.
• Fabrication and characterization of Mo-doped BiVO4 photoanodes.
• Assembly of a tandem device with a photovoltaic cell for water splitting.

Main Results:

• DFT identified Molybdenum (Mo) as a dual-role dopant enhancing charge transport and stabilizing the monoclinic scheelite phase.
• Mo-doped BiVO4 (3Mo-BVO) exhibited 96.2% charge separation efficiency at 1.23 V vs. RHE.
• A tandem device with 3Mo-BVO photoanode and NiFeOx co-catalyst achieved a 4.7% STH efficiency.

Conclusions:

• Mo doping effectively suppresses inactive phases and improves charge separation in BiVO4 photoanodes.
• The MOD method combined with Mo doping provides a scalable route to high-performance photoanodes.
• This work demonstrates a promising strategy for efficient solar water splitting using engineered BiVO4 photoanodes.