Photocatalytic degradation of an organophosphorus pesticide using a ZnO/rGO composite

Abstract

A zinc oxide (ZnO)/reduced graphene oxide (rGO) nanocomposite was synthesized via a hydrothermal synthesis method and used for the photocatalytic degradation of dimethoate. In the synthesis process of the ZnO/rGO nanocomposite, hexamethylenetetramine (HMT) was used as both a mineralizer and reducing agent. When the ZnO nanoparticles formed on the surfaces of graphene oxide sheets, the sheets were simultaneously reduced by HMT to form rGO. The photodegradation rate and photodegradation efficiency of dimethoate by the ZnO/rGO nanocomposite were 4 and 1.5 times, respectively, higher than those of bare ZnO. The ZnO/rGO nanocomposite possessed a high surface area of 41.0 m² g⁻¹ and pore volume of 4.72 × 10⁻³ cm³ g⁻¹, which were conducive to the adsorption and mass transfer of pesticides and oxygen. The enhanced photocatalytic performance of the ZnO/rGO nanocomposite was attributed to the decrease in electron–hole recombination rate and effective carrier transport caused by the presence of rGO. Photoelectrochemical measurements confirmed that the nanocomposite exhibited a high charge transfer rate at the ZnO/rGO interface. These results indicate that ZnO/rGO nanocomposites have great application potential in pollutant degradation.