Fabricating heterostructured photocatalysts composed of semiconductors with staggered band energies has proved to be an efficient approach to improve the carrier separation and visible light absorption. In addition to the intrinsic material properties for suitable band alignments, carefully controlled morphology that exposes the heterojunction interfaces to the reaction solution can enhance the conversion of photons to electrons. In particular, well-controlled shell coverage in the core/shell heterostructure is highly desirable, and a reliable methodology is urgently needed to be developed to control the coverage of the shell materials.
Now, new research from Tianjin University describes the fabrication of an efficient g-C3N4/BiVO4 heterojunction photocatalyst with BiVO4 networks decorated by discrete g-C3N4 nano-islands, forming high quality island-core interfaces in contact with the reaction solution with an optimized interface exposure. Based on a template-assisted mechanism, the coverage of g-C3N4 islands on the BiVO4 core can be easily tuned through a simple thermal annealing process. The as-synthesized g-C3N4/BiVO4 photocatalyst shows superior visible light photocatalytic activities.
In addition to excellent visible light response, the enhanced photocatalytic activity can be ascribed to the increased charge separation efficiency, fully exposed reactive sites, and separated redox reaction sites, which is likely due to the existence of a steady state photocurrent within the area near the g-C3N4-BiVO4 islands-core interfaces, driven by the internal built-up electric field at the interface. The researchers have provided a general and feasible approach to construct island-core structures with controllable coverage through a simple thermal annealing process based on a template-assisted mechanism, and will hopefully stimulate more studies exploring the shell coverage in the huge amount of the existing core-shell heterostructured photocatalysts.