## 1 Introduction
In addition, photocatalytic reduction can be achieved using solar energy, making it a sustainable and environmentally friendly process. However, there are still some challenges in implementing photocatalytic reduction on a large scale. These include improving the quantum efficiency of the process, increasing the selectivity for the desired product, and reducing the cost of the catalyst [4; 5; 9]. Future research efforts will focus on overcoming these challenges to make photocatalytic reduction a more practical and efficient method for converting CO\({}_{2}\) into useful chemicals. During the last decades, various semiconductors have been investigated as potential candidate photocatalysts for efficient and practical CO\({}_{2}\) reduction, such as TiO\({}_{2}\)[6], ZnGa\({}_{2}\)O\({}_{4}\)[4], LaPO\({}_{4}\)[9], WO\({}_{3}\)[10], ZnS [11; 12], and bismuthates [13; 14]. As one of the most investigated photocatalysts, TiO\({}_{2}\) has a wide range of applications, including environmental pollution control, energy conversion, and organic wastewater treatment. The photocatalytic activity of TiO\({}_{2}\) is based on its ability to absorb ultraviolet light and generate electron-hole pairs, which are responsible for the activation of oxygen and the reduction of electron acceptors. The holes generated in the valence band of TiO\({}_{2}\) can react with water to produce hydroxyl radicals (\(\bullet\)OH), while the electrons in the conduction band can reduce the adsorbed species on the catalyst surface. TiO\({}_{2}\) photocatalysis has been widely used for environmental purification, including the decomposition of organic pollutants in air and water. In addition, TiO\({}_{2}\) photocatalysis can also be used for energy conversion, such as in solar cells and artificial photosynthesis, to convert solar energy into chemical energy. The performance of TiO\({}_{2}\) photocatalysts is influenced by factors such as crystal structure, particle size, and surface structure. Nanostructured TiO\({}_{2}\) with a smaller particle size has a higher specific surface area and more active sites, resulting in higher photocatalytic activity. In addition, the surface structure and morphology of the catalyst can also affect its performance by providing more active sites or faster electron transfer kinetics. Despite its wide range of applications, TiO\({}_{2}\) photocatalysis still faces challenges such as its low activity in the visible light region and its sensitivity to water quality and environmental conditions [6; 15; 16]. Future research should focus on overcoming these limitations to further improve the efficiency and practicality of TiO\({}_{2}\) photocatalysis in various applications. Up to now, many efforts have been devoted to improving the photocatalytic activity of semiconductors on CO\({}_{2}\) reduction, such as doping or modification with foreign elements, composition with other semiconductors, and the adjustment of nanostructures [11; 17; 18; 19]. However, most of these photocatalysts exhibit poor photocatalytic performance for practical application, because of the large band gap and the rapid recombination of charge carriers [20; 21]. It is still necessary to further improve photocatalytic performance by developing a new type of photocatalyst with strong redox ability, a visible response, and high photocatalytic performance. Zn\({}_{2}\)SnO\({}_{4}\), also known as ZTO, is a ternary oxide semiconductor material with a cubic crystal structure in which zinc and tin exist in a tetrahedral coordination form and oxygen exists in a bidentate coordination form. The band gap of Zn\({}_{2}\)SnO\({}_{4}\) material at room temperature is about 3.6 eV, which has good insulating properties and chemical stability. In addition, Zn\({}_{2}\)SnO\({}_{4}\) also has high electrical conductivity, fast electron transfer, high chemical sensitivity, and excellent visible light absorption. Zn\({}_{2}\)SnO\({}_{4}\) has wide application value in many fields. Zn\({}_{2}\)SnO\({}_{4}\) is a versatile material with potential for a wide range of applications.