## 1 Introduction  
The excessive emission of CO\({}_{2}\) has caused great harm to the environment and human beings. CO\({}_{2}\) is the main greenhouse gas that causes global warming, which has brought about a series of environmental problems, including melting ice caps and glaciers, rising sea levels, changes in precipitation patterns, more extreme weather events, and biodiversity loss [1, 2]. The increase in CO\({}_{2}\) concentration in the atmosphere has also led to a decrease in the pH value of the ocean, resulting in ocean acidification. This has damaged marine ecosystems and the ability of coral reefs to survive, affecting fisheries and other industries that rely on ocean resources. Moreover, human health is also affected by high concentrations of CO\({}_{2}\) in the atmosphere. Exposure to high concentrations of CO\({}_{2}\) can cause respiratory problems, such as asthma and other respiratory infections. To address the issue of excessive CO\({}_{2}\) emissions, it is necessary to take measures to reduce emissions. This includes using clean energy sources, such as solar, wind, and nuclear energy, instead of coal and other fossil fuels that emit large amounts of CO\({}_{2}\)[3]. In addition, planting trees and other carbon-absorbing plants can help absorb some of the excess CO\({}_{2}\) in the atmosphere. Finally, policies should be implemented to encourage more sustainable practices and reduce emissions from vehicles and other sources. The burning of fossil fuels, such as coal, oil, and natural gas has produced a large amount of greenhouse gas emission, especially CO\({}_{2}\), which has caused global climate change and environmental problems [4, 5]. To solve these serious problems, developing clean and renewable energy sources, such as solar energy, is of great importance for human beings [6]. As a new type of technology, the photocatalytic reduction of CO\({}_{2}\) into hydrocarbons has drawn a lot of attention, as it converts the greenhouse gas, CO\({}_{2}\), into renewable energy via solar light irradiation, solving the energy crisis and greenhouse effect simultaneously [7, 8, 9]. One of the most commonly used photocatalysts for CO\({}_{2}\) reduction is titanium dioxide (TiO\({}_{2}\)), which has a high photocatalytic activity and stability under UV light. The photocatalytic reduction process typically involves two main steps: (1) the absorption of light by the photocatalyst, resulting in the generation of electron-hole pairs, and (2) the transfer of the electrons to a reducing agent, such as H\({}_{2}\) or CO, to generate the desired product. In the first step, the photocatalyst absorbs light energy, typically in the form of visible or ultraviolet light, and generates excited electrons. These electrons are transferred to the surface of the photocatalyst, where they can participate in reduction reactions. The excited electrons reduce the CO\({}_{2}\) molecule, which is adsorbed on the photocatalyst surface. This reduction process involves the addition of electrons to the CO\({}_{2}\) molecule, reducing it to a lower-energy species. One common product of this reduction process is methane (CH\({}_{4}\)), but other compounds such as methanol or formic acid can also be produced. The overall process of photocatalytic reduction of CO\({}_{2}\) involves several steps, including the absorption of light by the photocatalyst, the generation of excited electrons, the reduction of CO\({}_{2}\), and the formation of the final product. The mechanism is highly efficient and can convert CO\({}_{2}\) into useful compounds without the need for external reducing agents. This process has attracted significant interest for its potential to convert waste CO\({}_{2}\) into valuable products while reducing the environmental impact of industrial processes. The main advantage of photocatalytic reduction is that it can convert CO\({}_{2}\) into useful chemicals without the need for high temperatures or pressures.