A novel supramolecular preorganization route for improving g-C3N4/g-C3N4 metal-free homojunction photocatalysis

Abstract

Heterojunction or homojunction construction has been demonstrated to be an effective method to boost photocarrier separation and transfer, leading to a greatly enhanced photocatalytic activity. However, the photocatalytic performance of conventional heterojunction or homojunction photocatalysts usually faces some challenges, such as low surface area, insufficient active sites, and poor interface contact area. In this research, for the first time, a novel graphitic carbon nitride/graphitic carbon nitride (g-C₃N₄/g-C₃N₄) metal-free homojunction was successfully synthesized by calcining the supramolecular precursor self-assembly formed between hydrothermal melamine and dicyandiamide. The novel g-C₃N₄/g-C₃N₄ metal-free homojunction features a nanomesh morphology with a high specific surface area, which is not detected in the other g-C₃N₄/g-C₃N₄ composites. In addition, the in situ formation of the homojunction creates abundant interface contact, which improves the charge transfer ability. As expect, the as-prepared sample exhibited significantly enhanced visible light activity for rhodamine B degradation compared to the use of g-C₃N₄ alone and was 4.3 times as active as conventional g-C₃N₄/g-C₃N₄ composites. The results presented in this paper demonstrate that the novel supramolecular pre-organization route is valuable for the creation of a g-C₃N₄ isotype homojunction with a large specific surface area and abundant interface contact. The feasibility of developing different supramolecular precursors for efficient C₃N₄ photocatalysis using simple hydrothermal melamine and other nitrogen-rich precursors is proposed.