New strategy for enhancing the photocatalytic degradation of sulfadiazine by polymerized carbon nitride: Modulation of short-lived radicals to long-lifetime reactive species

Modulating the generation pathway of reactive species is an appealing approach for improving the photocatalytic performance of polymerized carbon nitride (PCN). In this study, boron-doped tubular PCN with carbon defects (BCNT) was synthesized via thermal polymerization. It was confirmed that boron dopants with adjacent carbon defects were introduced into the heptazine ring of carbon nitride, which redistributed the localized electron density and strengthened the adsorption of O2. The generation of long-lived reactive species, e.g., •O2− and 1O2, was thus enhanced markedly, whereas the generation of short-lived radicals, e.g., •OH, was decreased. Additionally, the electron-deficient boron dopants and neighboring carbon defects synergistically reduced the Gibbs free energy of H2O2 formation, thereby promoting its participation in photocatalytic reactions. Although •O2− was the main reactive species, 1O2 and H2O2 also played considerable roles. Consequently, the photocatalytic degradation of sulfadiazine by BCNT was significantly enhanced (by 6.39 times) compared to that by PCN.