Structurally modified graphitic carbon nitride with highly photocatalytic activity in the presence of visible light

The development of highly functionalized photocatalysts for the degradation of organic pollutants is an important environmental remediation objective. To this end, we report a facile synthetic strategy for the production of doubly modified graphitic carbon nitride (CN) with nitrogen deficiencies and an asymmetric planar structure. The addition of KOH and oxamide (OA) during the thermal polymerization of urea yields a photocatalyst that exhibits a significantly higher photocatalytic activity for the degradation of bisphenol A (BPA) compared to that of pure CN. The enhanced photocatalytic activity for the degradation of BPA exhibited by the doubly modified CN (KOH-OA-CN) structure is ascribed to a) a considerable red shift in its light absorption response compared to that of CN, and b) to its modulated energy band structure with a sub-bandgap and an increased charge separation efficiency. Furthermore, we confirmed that the in situ formation of cyano groups in the KOH-OA-CN photocatalyst acted as strong electron-withdrawing groups that efficiently separated and transferred photogenerated charge carriers to the surface of the photocatalyst. This study provides novel insights in the in situ modification strategy for g-C3N4, and also introduces KOH-OA-CN as a highly efficient, visible-light-responsive photocatalyst for use in environmental-remediation applications.