Garland-like intercalated carbon nitride prepared by an oxalic acid-mediated assembly strategy for highly-efficient visible-light-driven photoredox catalysis

Microstructure modulation has emerged a great potential to effectively improve photocatalytic efficiency of graphitic carbon nitride for solar H2 production from water splitting and clean organic synthesis. Bearing the merits of the 2D g-C3N4 nanosheets and the ring-structured materials in mind, an intercalated g-C3N4 ring composed of nanosheets can be envisioned to exhibit outstanding photocatalytic performance. However, the synthesis of this kind of g-C3N4 ring has never been realized. In this work, for the first time, a novel three-dimensional (3D) garland-like intercalated graphitic carbon nitride (GICN) has been successfully prepared through a facile oxalic acid-mediated molecular assembly strategy followed by thermal polymerization with the low-cost and commercially available melamine and cyanuric acid as starting materials. GICN integrates the merits of both the 2D g-C3N4 nanosheets and the ring-structured materials, which creates a highly efficient and practical photocatalyst for both the photoreductive water splitting to solar H2 and the photooxidative homocoupling of amines to imines (O2 activation) and CC cleavage of olefins to carbonyls (H2O2 activation), ascribed to its more exposed active sites and the enhanced light harvesting and improved separation efficiency of charge carriers. This work not only produces an outstanding graphitic carbon nitride photocatalyst, but also presents some guidance for designing other advanced graphitic carbon nitride materials with outstanding optical, electrical, and adsorption properties for versatile applications in the fields of thermocatalysis, photocatalysis, photoelectrocatalysis, optoelectronic devices, CO2 capture, supercapacitor, and drug-delivery systems.