In this study, pure ZnO, CeO 2 and ZnO/CeO 2 nanocomposites were synthesized using a thermal decomposition method and subsequently characterized using different standard techniques. Highresolution X-ray photoelectron spectroscopy measurements confirmed the oxidation states and presence of Zn 2+ , Ce 4+ , Ce 3+ and different bonded oxygen species in the nanocomposites. The prepared pure ZnO and CeO 2 as well as the ZnO/CeO 2 nanocomposites with various proportions of ZnO and CeO 2 were tested for photocatalytic degradation of methyl orange, methylene blue and phenol under visible-light irradiation. The optimized and highly efficient ZnO/CeO 2 (90:10) nanocomposite exhibited enhanced photocatalytic degradation performance for the degradation of methyl orange, methylene blue, and phenol as well as industrial textile effluent compared to ZnO, CeO 2 and the other investigated nanocomposites. Moreover, the recycling results demonstrate that the ZnO/CeO 2 (90:10) nanocomposite exhibited good stability and long-term durability. Furthermore, the prepared ZnO/CeO 2 nanocomposites were used for the electrochemical detection of uric acid and ascorbic acid. The ZnO/ CeO 2 (90:10) nanocomposite also demonstrated the best detection, sensitivity and performance among the investigated materials in this application. These findings suggest that the synthesized ZnO/CeO 2 (90:10) nanocomposite could be effectively used in various applications.In recent years, many researchers have focused on semiconductor nanomaterials because of their versatile properties and applications [1][2][3] . Generally, such nanomaterials enable the highly sensitive detection of numerous enzymes and can degrade various organic pollutants 4-6 . Nanosemiconductor-based biosensing and photocatalysis are essential applications for monitoring, controlling and improving the conditions of the ecosystem [1][2][3][4][5][6] . Among the various semiconductors, zinc oxide (ZnO) is an efficient, non-toxic and low-cost material with a large band-gap energy (~3.2 eV). ZnO exhibits many fascinating properties and is used in multiple applications, including paints, sunscreens, solar cells, photocatalysts, antibacterial agents, biosensors, and gas sensors 7-11 .Currently, textile dyes are the most important worldwide source of water pollution because of their release into water resources 7 . Water pollution is considered to be a major factor that affects the environment; hence, solving this issue will benefit human living conditions. In recent decades, many researchers have investigated the use of semiconductor nanometal oxides for the photocatalytic treatment of wastewater and other pollutants. This approach was believed to be the best way to reduce the contaminants present in the water under different light sources. The photocatalytic process of treating pollutants is the most advanced method because it requires a smaller amount of catalyst and generates almost no or very few harmful by-products 3,4,8 . Metal oxides are the most convenient materials used as photocatalysts ...
