Novel electrochemical synthesis of N-doped ZnO–rGO films for the photoelectrocatalytic degradation of antibiotics

Abstract

This study involved the synthesis of modified ZnO materials for photoelectrocatalysis (PEC) by a simple and environmentally friendly electrochemical procedure. The objective was to assess their capacity to photochemically breakdown ofloxacin (OFX) in an aqueous solution. To enhance the PEC performance of pure ZnO, a zinc oxide–reduced graphene oxide (ZnO–rGO) composite was synthesized through an electrochemical co-deposition process without the use of a reducing agent. Subsequently, ZnO–rGO was doped with N (ZnO–rGO:N) to further augment the PEC performance of the photoanode. The surface morphology, microstructure, and optical characteristics of the materials were systematically investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and UV–visible spectroscopy. The parameters for synthesizing ZnO–rGO were optimized based on the experimental results” if it can more simply convey your intended meaning. Electrochemical tests demonstrated that N-doping significantly enhanced the photocurrent density of the ZnO–rGO films, which reached 15.14 μA cm⁻², representing 1.6- and 1.3-fold enhancements with respect to those of pure ZnO (9.25 μA cm⁻²) and ZnO–rGO (12.0 μA cm⁻²), respectively. Additionally, the band gap in ZnO was narrowed from 3.4 to 3.18 eV owing to rGO co-deposition and N-doping. After 180 min of Xe lamp irradiation, with a bias potential of 0.7 V (referenced to Ag/AgCl), ZnO–rGO:N demonstrated an OFX degradation rate of 55.7 %. Thus, the N-doped material exhibited higher PEC performance than either ZnO (31.8 %) or ZnO–rGO (36.3 %), implying its enhanced PEC capabilities. Therefore, the modified ZnO-based photoanode prepared using the straightforward electrochemical deposition method satisfied the objective of this study, which was to enhance its PEC activity while providing a viable foundation for nitrogen doping through electrochemical methods.