A green approach to synthesis of Ag-doped CeO2 nanorods embedded reduced graphene oxide nanocomposite for excellent photocatalytic and antimicrobial activity

In this paper, the Ag-doped cerium oxide nanorods embedded reduced graphene oxide (Ag@CeO2/rGO) nanocomposite was synthesized via Punica Granatum peel extract for for photocatalytic degradation of methylene blue (MB) and 4-nitrophenol (4-NP). The microstructural results confirmed the successful decoration of Ag-doped CeO2 nanorods on rGO matrix. The photocatalytic properties, including photocatalytic degradation, charge transfer kinetics and photocurrent generation, are systematically investigated using electrochemical impedance spectroscopy (EIS), photocurrent transient response (PCTR) and open circuit voltage decay (OCVD). The results of photocatalytic dye degradation measurements indicated that Ag@CeO2/rGO nanocomposite is more effective than pristine CeO2 to degrade the MB dye, and the degradation rate reached 100 % in 60 min. The decomposition of MB with Ag@CeO2/rGO nanostructure followed first-order reaction kinetics with a reaction rate constant (Ka) of 0.0198 min 1. The EIS and OCVD measurements revealed that the Ag doping and incorporation of rGO could suppress the recombination probability in CeO2 by the separation of photo-generated electron-hole pairs, which leads to the enhanced photocurrent generation and photocatalytic activity. The photocurrent density of Ag@CeO2/rGO, CeO2/rGO and pristine CeO2 are 215, 167.4 and 98.8 mAcm(-2), respectively.