Ag-doped ZnO nanorods embedded reduced graphene oxide nanocomposite for photo-electrochemical applications

Abstract

In this paper, the Ag-doped zinc oxide nanorods embedded reduced graphene oxide (ZnO:Ag/rGO) nanocomposite was synthesized for photocatalytic degradation of methyl orange (MO) in the water. The microstructural results confirmed the successful decoration of Ag-doped ZnO 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 ZnO:Ag/rGO nanocomposite is more effective than pristine ZnO to degrade the MO dye, and the degradation rate reached 40.6% in 30 min. The decomposition of MO with ZnO:Ag/rGO nanostructure followed first-order reaction kinetics with a reaction rate constant ( K _a) of 0.01746 min ⁻¹. The EIS, PCTR and OCVD measurements revealed that the Ag doping and incorporation of rGO could suppress the recombination probability in ZnO by the separation of photo-generated electron–hole pairs, which leads to the enhanced photocurrent generation and photocatalytic activity. The photocurrent density of ZnO:Ag/rGO, ZnO/rGO and pristine ZnO are 206, 121.4 and 88.8 nA cm ⁻², respectively.