Metal-free efficient photocatalyst for stable visible-light photocatalytic degradation of refractory pollutant

- Metal-free h-BN/g-C3N4 heterojunction prepared by a facile in-situ growth strategy.
- h-BN/g-C3N4 exhibited enhanced photocatalytic activity for TC and RhB degradation.
- h-BN nanosheets in this system serve as an efficient holes transfer channel.
- The photo-degradation is dominant by the hole and O2− while without OH radicals.
- Larger surface area and enhanced separation of photoinduced carriers are obtained.

The photocatalytic performance of the star photocatalyst g-C3N4 is restricted by the insufficient solar light absorption, low surface area and the fast recombination of photogenerated electron-hole pairs. The present study developed a facile in situ method to construct hexagonal boron nitride (h-BN) decorated g-C3N4 metal-free heterojunction with the aim to greatly enhance the surface area and promote the charge separation. The physical, chemical and optical properties of the resulted samples were thoroughly characterized. The photocatalytic performance of h-BN/g-C3N4 composites were evaluated under visible light irradiation using antibiotic tetracycline (TC) and rhodamine B (RhB) as target pollutants. Results showed that h-BN/g-C3N4 composites exhibited much higher photocatalytic activity than pure g-C3N4 and h-BN. The optimum photocatalytic efficiency of BC-3 sample for the degradation of TC was about 2.3 and 60.3 times higher than that of individual g-C3N4 and h-BN, respectively. Meanwhile, it was about 7.3 and 11.8 times higher than that of individual g-C3N4 and h-BN for RhB degradation, respectively. The enhanced photocatalytic activity of h-BN/g-C3N4 composite is mainly attributed to the larger surface area and the unique physicochemical properties of h-BN nanosheet which acts as a promoter for photoexcited holes transfer. This work indicates that the metal-free h-BN/g-C3N4 hybrid photocatalyst is a promising material in wastewater control.

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