Vacancy defect engineered BiVO₄ with low-index surfaces for photocatalytic application: a first principles study

Area of Science:

• Materials Science
• Surface Science
• Computational Chemistry

Background:

• Bismuth vanadate (BiVO4) is a promising photocatalyst for water splitting.
• Improving BiVO4's efficiency requires strategies like defect engineering.
• Understanding surface properties is key to optimizing photocatalytic performance.

Purpose of the Study:

• To systematically investigate the effects of Bi, V, and O vacancies on the (001) and (011) surfaces of BiVO4.
• To analyze the electronic properties, band alignments, and Gibbs free energy of pristine and defective BiVO4.
• To determine the influence of defects on water splitting capabilities.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Analysis of electronic structures and band gaps.
• Evaluation of band edge positions and reaction free energies.

Main Results:

• Pristine BiVO4 surfaces exhibit distinct band gaps.
• Oxygen vacancies induce n-type semiconducting behavior, while Bi and V vacancies lead to p-type behavior.
• Hole accumulation favors the (011) surface, and electron accumulation favors the (001) surface.
• Oxygen and Bi vacancies can reduce the overpotential for water splitting reactions.

Conclusions:

• Defect engineering, particularly O and Bi vacancies, can tune the electronic properties of BiVO4 surfaces.
• Specific vacancies can improve charge carrier separation and reduce reaction overpotentials.
• Theoretical insights guide the development of more efficient BiVO4-based photocatalysts for water splitting.