Synthesis of CeO2/ZrO2/ZnO nano alloy oxide and investigation of photocatalysis of naphthol orange under sunlight

Abstract

Novel metal-like cerium- and zirconium-doped ZnO photocatalysts were prepared herein with various proportions of molar ratios via a cost-effective co-precipitation method. The effects of novel metal doping on the photocatalytic activity of ZnO were studied. Various techniques were used to investigate the structural, morphological, and elemental composition, particle size, optical properties, and catalytic activity of the synthesized photocatalysts. It was found that the crystallite size and particle size of the nano alloy oxides were 15.12 ± 1 and 5 ± 1 nm, respectively, and the surface morphology of the nanoparticles indicated a satisfactory surface area. Among all synthesized nanocomposites, Ce_xZr_xZn_xO₅ (x = 1) [CZ₁Z₂-A] exhibited satisfactory photo-oxidation activity against naphthol orange (NO) under sunlight with a rate constant of 57.5 × 10⁻³ min⁻¹. The effects of pH, inorganic salts, dye concentrations, and catalytic dosage on NO degradation were studied. A probable mechanistic pathway for the degradation of NO in the presence of CZ₁Z₂-A was proposed, and studies of sacrificial agents indicated that superoxide radical anion (O₂˙⁻) was the main accountable active species in NO degradation. In addition, CZ₁Z₂-A exhibited excellent recyclability potential, and XRD studies revealed that there was no change in the crystal structure before or after degradation, which indicated its high stability. The intriguing finding was that Ce- and Zr-doped ZnO did not exhibit satisfactory catalytic performance in the photo-oxidation of NO. However, the composite formula of Ce_xZr_xZn_xO₅ (x = 1) with a 1 : 1 : 1 ratio of metal ions offered excellent catalytic activity.