Designing ultrathin Ag-embedded g-C3N4 nanocomposites for enhanced disinfection performance under visible light

Using ammonium chloride (NH 4 Cl) as a gas template, we conveniently fabricated ultrathin two-dimensional layered silver-embedded graphitic carbon nitride nanosheets (AgCNS) by melamine blowing method with triazine groups of pristine graphite carbon nitride. Compared with bulk g-C 3 N 4 (BCN) and g-C 3 N 4 nanosheets (CNS), the antibacterial activity of the optimized AgCNS-5 at a minimum inhibitory concentration (MIC) of 40 ppm against Escherichia coli ( E. coli ) was significantly enhanced. Under visible-light irradiation, E. coli could be completely killed by 100 µg·mL −1 of AgCNS-5 within 30 min. The mechanism of enhanced antibacterial activity was systematically investigated by ultraviolet-visible diffuse reflectance spectra (UV-vis DRS), photoluminescence spectra (PL), electrochemical impedance spectroscopy (EIS), and photogenerated current densities. Surface plasmonic resonance (SPR) of Ag nanoparticles (NPs) with g-C 3 N 4 was found to lead to an enhancement of visible light absorption and an acceleration of photo-induced electron-hole migration/separation, which is responsible for the enhanced photocatalytic bactericidal performance. Through trapping experiments and electron spin resonance spectroscopy (ESR) techniques, the bactericidal mechanism was revealed that the species of •O 2 − and •OH play important roles in antibacterial process. Considering the facile preparation and excellent performance, AgCNS-5 may be a promising and competitive visible-light-driven candidate toward sterilizing agent.