Facile fabrication of a visible-light stable metal-free g-C3N4/COF heterojunction with efficiently enhanced photocatalytic activity

Abstract

The development of metal-free photocatalyst systems is becoming a new trend in practical applications. We proposed a simple strategy for the fabrication of g-C₃N₄/COF 2D/2D heterojunction photocatalysts, and studied their photocatalytic activity and stability. g-C₃N₄ nanosheets (CNNSs) were prepared by thermal condensation and TPA-COF was grown on the surface of the CNNS to obtain a COF modified CNNS. Compared with the pure CNNS and TPA-COF, CNNS/TPA-COF heterojunction photocatalysts have higher removal efficiency towards organic dye rhodamine B (RhB). The enhancement of the photocatalytic performance may be due to the fact that after the introduction of the large conjugated COF, the absorption of visible light and the separation of photogenerated electron and hole pairs of CNNSs are promoted, which can be verified by the high photocurrent density, small electrochemical impedance radius, weak fluorescence intensity, and broad UV-visible absorption regions. In addition, we have proposed a possible mechanism for CNNS/TPA-COF photocatalysis. The introduction of a polymeric heterojunction will provide a reference method for the design of photocatalysts with low cost, high performance and high stability.