Tailoring morphology symmetry of bismuth vanadate photocatalysts for efficient charge separation

In a study published in the journal Science China Chemistry and led by Prof. Rengui Li (State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences), a distinct charge separation difference has been found via rationally tailoring the morphology symmetry of BiVO₄ photocatalyst.

Interestingly, for octahedral BiVO₄ crystals, photogenerated electrons and holes can be separated between edges and quasi-equivalent facets. However, as for truncated octahedral BiVO₄, photogenerated electrons tend to transfer to {010} facets while photogenerated holes prefer to accumulate on {120} facets, thus realizing the spatial separation of photogenerated charges between different facets.

Morphology tailoring of BiVO₄ crystals leads to a significantly improved photogenerated charge separation efficiency and photocatalytic water oxidation activity. The built-in electric field for driving the separation of photogenerated electrons and holes is considered to be modulated by tuning the morphology symmetry of BiVO₄ crystals.

"Among artificial photosynthesis via photocatalytic water splitting which enables the direct utilization and storage of solar energy into chemical fuels, photo-induced charge transfer from a photocatalyst to catalytic surface sites is vital in ensuring solar energy utilization efficiency," Li says.

"Therefore, it is of great significance to explore the influence of morphology and facet on the charge separation. Based on the previous research on spatial charge separation between different facets in semiconductor crystals, taking bismuth vanadate with low-symmetry structure as a platform, this work has revealed the significant role of morphology symmetry in charge separation, which is important to facilitate the rational design of artificial photocatalysts."