Reduced and modified graphene oxide with Ag/V2O5 as a ternary composite visible light photocatalyst against dyes and pesticides

Abstract

Water pollution by dyes and pesticides poses significant threats to our ecosystem. In this research, a visible-light ternary composite photocatalytic system was fabricated using graphene oxide (GO) by reducing with N2H4, modifying with KOH, and decorating with Ag/V2O5. The fabricated photocatalysts were characterized through FTIR, SEM, XRD, BET, PL, EDX, ESR, UV–vis spectroscopy, TGA, ESI-MS, and Raman spectroscopy. The point zero charge of the reduced and modified GO (RMGO/Ag/V2O5) was measured to be 6.7 by the pH drift method. This ternary composite was able to achieve complete removal of methyl orange (MO) and chlorpyrifos (CP) in solutions in 80 min under the optimum operation conditions (e.g., in terms of pollutant/catalyst concentrations, pH effects, and contact time). The role of active species responsible for photocatalytic activity was confirmed by scavenger analysis and ESR investigations. The potential mechanism for photocatalytic activity was studied through a fragmentation process carried out by MS analysis. Through nonlinear fitting of the experimental data, MO and CP exhibited the best fit results with the pseudo 1st-order kinetics (quantum yields of 1.07 × 10−3 and 2.16 × 10−3 molecules photon−1 and space-time yields of 1.53 × 10−5 and 2.7 × 10−5 molecules photon−1 mg−1, respectively). The structure of the nanomaterials remained mostly intact to support increased stability and reusability of the prepared photocatalysts even after 10 successive regeneration cycles.