Efficient photodegradation of methyl orange dye using electrogenerated copper-zinc oxide hybrid

Abstract

A photoactive Cu-doped ZnO (Cu/ZnO) hybrid was synthesized via a simple electro-generation procedure. The resultant catalyst was then subjected to UV–vis DRS and BET analysis for band gap and porosity properties studies. The photocatalytic efficiency of the Cu/ZnO hybrid was then evaluated via discoloration reaction of dye pollutant, methyl orange (MO) under visible light irradiation. To study the effect of Cu loadings on the hybrid catalyst performance, a series of catalysts with different Cu wt.% were synthesized and tested for MO degradation. As result, ZnO doped with 5 wt% Cu was found as the most active catalyst with 100 % MO removal followed by 3 wt% Cu/ZnO (94 %), 7 wt% Cu/ZnO (71 %) and 10 wt% Cu/ZnO (40 %). Whereas, in the presence of pure ZnO, only 23 % MO was managed to be degraded, remarking its low catalytic reactivity compared to Cu/ZnO hybrids, especially 5 wt% Cu/ZnO. This might be due to the increase in surface area and lower band gap of 5 wt% Cu/ZnO (3.11 eV) compared to ZnO (3.20 eV) as analyzed by BET and UV–vis DRS respectively. Meanwhile, the optimum reaction conditions were found to be pH 3, 10 mg/L initial dye concentration, and 0.38 g/L of 5 wt% Cu/ZnO. Conclusively, the electrogenerated Cu/ZnO catalyst was highly capable of degrading methyl orange dye pollutants and therefore has a high potential for future wastewater treatment application.