Enhanced photocatalytic reduction of nitroaromatic compounds using modified Ag-decorated magnetic g-C3N4 heterojunctions hybrid with arginine and cyanoguanidine

Abstract

This study presents the development of a magnetic graphitic carbon nitride (g-C3N4) nanocomposite modified with arginine (Arg) and cyanoguanidine (CG), followed by the green synthesis of Ag nanoparticles. The resulting nanocomposite, named Ag/Fe3O4-g-C3N4-Arg-CG, was thoroughly characterized and exhibited remarkable efficiency as a nanocatalyst for the photocatalytic reduction of nitroaromatics under both LED and solar light irradiation. The incorporation of Fe3O4 and Ag nanoparticles significantly broadened the visible light absorption range, enhanced electron excitation, and effectively inhibited electron-hole recombination. Ag nanoparticles further facilitated electron transport by serving as electron acceptors and photosensitizers. The arginine modification introduced functional groups that promoted charge separation and increased surface area, while cyanoguanidine optimized the electronic structure, improving light absorption and compatibility in aqueous environments. Under 2 h of solar and LED light irradiation, the photocatalyst achieved nitrobenzene reduction yields of 98 % and 100 %, respectively, with methanol identified as the optimal solvent. The Ag/Fe3O4-g-C3N4-Arg-CG nanocatalyst also demonstrated excellent stability and recyclability, showing minimal yield loss over six reaction cycles. These results mark a significant advancement in photocatalysis, offering promising potential for environmental remediation and sustainable chemical processes.