A Synergistic Ag-Fe/rGO Photocatalyst for the Visible-Light Degradation and Detoxification of 2-Nitrophenol

Abstract

Ag-Fe engineered on Reduced graphene oxide (Ag-Fe/rGO) was prepared and analysed as an effective photocatalyst in the degradation of 2-Nitrophenol (2-NP) suspended in water. The catalyst was also highly active as it was able to degrade almost fully when exposed to visible light in a minimal reaction time. The kinetic study revealed that the degradation was of pseudo-first-order and the rate constants grew with increase in temperature. The thermodynamic researches indicated the activation energy of about 50.0 kJ mol^-1 and also indicated that there is a kinetically controlled reaction whereas the positive change in entropy indicated an increase in disorder in the formation of the activated complex. The Ag-Fe/rGO photocatalyst was highly stable and reusable during a series of cycles, and the activity decreased only slightly. The mechanistic studies revealed that synergistic effects of Ag-Fe nanoparticles (Ag-Fe NPs) and the rGO contribute to the favorable charge separation and the increase in reactive oxygen species (OH and O^2-), which dominated the oxidative degradation of 2-NP. The results show that Ag-Fe/rGO is a potential, reusable, and very effective photocatalyst in the decontamination of nitroaromatic pollutants in water, and can be used in practical applications in the treatment of waste water.