In Situ Fabrication of a Highly Active Heterophase Junction for Photocatalytic Water Oxidation through Dual Modulation of Phase Composition and Micromorphology of BiVO4.

Photocatalytic water oxidation constitutes a pivotal reaction step in the development of artificial photosynthetic systems. Among prospective photocatalysts, BiVO4 is widely regarded as an ideal candidate for visible-light-driven water oxidation owing to its favorable band gap energy. Nevertheless, its practical implementation remains impeded by rapid photogenerated charge-carrier recombination and inefficient charge transport, factors that severely constrain the oxygen evolution efficiency. To address this challenge, this study developed a hydrothermal strategy for the in situ fabrication of BiVO4 heterophase junctions by precisely tuning the pH, precursor concentration, and surfactant dosage. Through these process optimizations, the morphology of BiVO4 was successfully engineered, enabling the targeted design of spherical, rod-shaped, flake-shaped, and block-shaped architectures, thereby significantly enhancing photocatalytic oxygen evolution activity. Notably, flake-shaped BiVO4(s-m) featuring high exposure of the {010} facets exhibits the optimal photocatalytic performance. Furthermore, the BiVO4(z-t)/BiVO4(s-m) heterophase junction was fabricated in situ at pH = 4 using 5 mmol of each precursor. Benefiting from efficient interfacial charge separation and optimized surface reaction kinetics, this heterophase junction exhibits an excellent oxygen evolution rate of 582.04 μmol/g/h, representing enhancements of 1.998- and 2.969-fold relative to the flake-shaped and block-shaped single-phase BiVO4(s-m) counterparts, respectively.