Environmentally sustainable biogenic fabrication of AuNP decorated-graphitic g-C3N4 nanostructures towards improved photoelectrochemical performances

Abstract

Noble-metal gold (Au) nanoparticles (NPs) anchored/decorated on polymeric graphitic carbon nitride (g-C₃N₄), as a nanostructure, was fabricated by a simple, single step, and an environmentally friendly synthesis approach using single-strain-developed biofilm as a reducing tool. The well deposited/anchored AuNPs on the sheet-like structure of g-C₃N₄ exhibited high photoelectrochemical performance under visible-light irradiation. The Au-g-C₃N₄ nanostructures behaved as a plasmonic material. The nanostructures were analyzed using standard characterization techniques. The effect of AuNPs deposition on the photoelectrochemical performance of the Au-g-C₃N₄ nanostructures was examined by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), incident photon-to-current efficiency (IPCE) and cyclic voltammetry (CV) in the dark and under visible-light irradiation. The optimal charge transfer resistance for Au-g-C₃N₄ nanostructures (6 mM) recorded at 18.21 ± 1.00 Ω cm⁻² and high electron transfer efficiency, as determined by EIS. The improved photoelectrochemical performance of the Au-g-C₃N₄ nanostructures was attributed to the synergistic effects between the conduction band minimum of g-C₃N₄ and the plasmonic band of AuNPs, including high optical absorption, uniform distribution, and nanoscale particle size. This simple, biogenic approach opens up new ways of producing photoactive Au-g-C₃N₄ nanostructures for potential practical applications, such as visible light-induced photonic materials for real device development.