Enhancement of visible-light-driven photocatalytic activity of carbon plane/g-C3N4/TiO2 nanocomposite by improving heterojunction contact

Abstract

Effective interface contact between components in heterojunction is crucial to realize high photocatalytic performance of photocatalyst. In this paper, the improvement of heterojunction contact by forming new ternary heterostructure via calcining the mixture of tetracycline and melamine to obtain the graphene-like carbon plane grafted g-C3N4 and then coupling it with TiO2 is reported. The unique carbon plane, which is anchored into g-C3N4 basal domains, acts as a significant role to achieve the sufficient ternary heterojunction contact in the novel carbon plane/g-C3N4/TiO2 nanostructure system. Under visible-light irradiation, the new ternary nanocomposite exhibits excellent photocatalytic activity for efficient removal of aqueous organic contaminants: methylene blue (98.6%), tetracycline (94.0%), and norfloxacin (95.3%), with the corresponding degradation rate constants of 0.0441, 0.0302, and 0.0125 min−1, respectively, which are 54.1, 9.8, and 9.4 times higher than that of the pure g-C3N4. The mechanism study indicates that the excellent photocatalytic activity is attributed to the effective heterojunction, which can successfully extend visible-light absorption, promote charge separation efficiency, and suppress recombination of the photocatalytic electron-hole pairs. Moreover, the electron spin resonance (ESR) assay and radical scavenger experiments demonstrate that the photogenerated holes (h+), superoxide anion radicals (O2−), and hydroxyl radical (OH) play vital roles in photocatalytic degradation process. Importantly, this work may open up novel insights into the design of ternary heterostructure with highly efficacious photocatalytic performance, which suggests attractive applications in environment protection.