A facile band alignment of polymeric carbon nitride isotype heterojunctions for enhanced photocatalytic tetracycline degradation

Abstract

Construction of heterojunctions is generally adopted to improve photocatalytic activity by enhancing photogenerated charge separation. In this study, metal-free phosphorus-doped g-C₃N₄ (PCN) and g-C₃N₄ (CN) isotype heterojunctions (PCN/CN) were prepared by a facile calcination strategy to significantly enhance the charge separation. The band offset between PCN and CN could drive the transfer of photogenerated electron–hole pairs, which helped reduce the recombination and prolong the lifetime of photoinduced charges. The optimum photocatalytic activity of PCN/CN composite for tetracycline degradation was approximately 3.8 and 2.8 times higher than that of pure CN and PCN, respectively; it also exhibited remarkable stability and repeatability. The possible mechanism was ascribed to efficient separation of photogenerated charges as well as promoted visible light absorption and enlarged surface area. The coupling of heterostructures between PCN and CN is an excellent method to overcome the intrinsic drawbacks of CN for photocatalytic wastewater purification.