Exploring the n–p type zinc oxide/copper oxide nanocomposite under Xenon light irradiation with enhanced photocatalytic activities for norfloxacin and methyl orange

Abstract

Metal oxides have demonstrated significant potential in water purification applications with the recent advancements in photocatalytic technologies. In this study, a ZnO/CuO nanocomposite was synthesized via a facile chemical co-precipitation method by successfully integrating zinc oxide and copper oxide semiconductors. The structural, compositional, and optical properties of pristine ZnO and the ZnO/CuO composite were comprehensively characterized. Under Xe light irradiation, the ZnO/CuO nanocomposite has exhibited superior photocatalytic performance, achieving substantial degradation of norfloxacin (NOR) and methyl orange (MO) within 120 min under optimized conditions. The degradation rates for 10 ppm concentrations of NOR and MO were calculated as k = 1.085 × 10^-2 min^-1 (99% degradation) and k = 3.849 × 10^-2 min^-1 (70% degradation), respectively. Kinetic analyses revealed that the degradation has followed pseudo-first-order kinetics, and observed to be consistent with the Langmuir–Hinshelwood model. Scavenger experiments have identified h⁺, O₂^•−, and ^•OH radicals as key species driving the photocatalytic degradation of MO, while O₂^•− primarily governed NOR degradation. In addition, the ZnO/CuO composite has maintained high photocatalytic efficiency after ten reuse cycles. These findings suggest that the ZnO/CuO nanocomposite is a promising candidate for the photocatalytic treatment of water contaminated with NOR and MO pollutants.