Multiple optimization strategies for improving photocatalytic performance of the h-BN/flower-ring g-C3N4 heterostructures: Morphology engineering and internal electric field effect

[Display omitted] •h-BN/flower-ring g-C3N4 heterojunction photocatalyst was synthesized.•The surface area of the catalyst was markedly increased by morphology engineering.•Characterizations and DFT calculations confirmed a type-II heterojunction.•Built-in electric field enabled effective separation of photogenerated carriers.•The BM-5 photocatalyst has remarkable photoelectric properties. Morphology adjustment and semiconductor coupling have great potential in effectively improving the photocatalytic activity of graphite carbon nitride (g-C3N4). Herein, an advanced heterostructure photocatalyst constructed by hexagonal boron nitride (h-BN) and flower-ring g-C3N4 (MCN) was successfully synthesized. Combining experiments and density functional theories (DFT) calculation, the photocatalytic process and charge transfer mechanism of h-BN/flower-ring g-C3N4 (BM) heterojunction were deeply studied. MCN had a large specific surface area, which increased the light absorption area and facilitated the exposure of active sites. Through the calculation of work function and energy band charge density distribution, a type II heterojunction was formed between h-BN and g-C3N4, and the migration direction of photogenerated charge was also consistent with this result. By calculating the three-dimensional differential charge density, it was verified that there was a built-in electric field at the interface between h-BN and g-C3N4. Electric field provided driving force for charge transfer. Based on the above positive factors, the photocatalytic performance of the composites was greatly improved, and the k value (0.0703 min−1) of photocatalytic degradation of TC was 33 times higher than that of bulk g-C3N4. This work provides a new strategy for the improvement of photocatalytic effects and broadens the applications of photocatalysts.