p-Type BiVO₄ for Solar O₂ Reduction to H₂O₂.

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Photoelectrochemical cells (PECs) offer sustainable solar energy conversion.
• Oxide semiconductors provide stability but lack p-type photocathodes.
• Bismuth vanadate (BiVO4) is typically n-type and used as a photoanode.

Purpose of the Study:

• To synthesize and characterize p-type monoclinic scheelite (ms) BiVO4.
• To evaluate its performance as a photocathode for solar fuel production.
• To understand the mechanism of p-type conductivity and hole transport.

Main Methods:

• Atomic doping of Ca2+ into ms-BiVO4 under an O2-rich environment.
• Synthesis and characterization of the material.
• Performance testing as a photocathode for solar O2 reduction.
• Computational investigation using hybrid density functional theory.

Main Results:

• Successfully prepared p-type ms-BiVO4 with a 2.4 eV bandgap.
• Demonstrated its use as a photocathode for solar O2 reduction to H2O2.
• Computational results confirmed Ca as an effective shallow acceptor dopant.
• Identified stable polaronic holes with low self-trapping energy.

Conclusions:

• p-type ms-BiVO4 can be achieved through Ca doping.
• This material shows promise for solar fuel and chemical production.
• Insights into polaronic hole behavior are crucial for designing oxide photocathodes.