# Recent Advances and Applications of Semiconductor Photocatalytic Technology
## 1 Introduction  
As industrialization accelerates, both energy and environmental issues arise. Nowadays, the world's major energy sources are still fossil energies, such as coal, oil, and natural gas. With the continuous development of industrialization, most fossil fuels are expected to be depleted in 21 st century. In addition, the use of fossil energy also causes severe pollution to the environment. In recent years, more and more serious air pollution and water pollution directly threaten human life and health [1]. In 1972, [PERSON] and [PERSON] found that the TiO\({}_{2}\) electrode can break down hydrogen in aquatic production under sunlight [2]. Since then, photocatalysis has attracted intense attention due to its direct conversion of solar energy to easily stored hydrogen, as well as its lack of environmental pollution. [PERSON] and [PERSON] then successfully oxidized CN\({}^{-}\) to OCN\({}^{-}\) using TiO\({}_{2}\) as a photocatalyst, an act which promoted and accelerated the application of photocatalysts in wastewater treatment [3]. Since then, TiO\({}_{2}\) has been used as a photocatalyst for a wide range of applications in the field of environmental management. The detailed research of photocatalyst technology also extends the potential applicationrange of photocatalysts. The main research directions at this stage are photocatalyst disinfection [4; 5; 6], photocatalytic hydrogen production [7; 8; 9; 10; 11], photocatalytic reduction of CO\({}_{2}\)[12; 13; 14; 15], photocatalyst wastewater treatment [16; 17; 18; 19; 20], and air purification [21; 22; 23]. However, photocatalytic technology is only at the laboratory stage, and there is still a long journey to apply this technology in practice [24].  
With the continuous development of photocatalytic technology, researchers have published many excellent reviews. For example, [PERSON] et al. [25] reviewed the use of nitrogen doping to modify oxide photocatalysts to improve their photocatalytic performance. [PERSON] et al. [26] outlined the application of graphene and its composites to photocatalysts. [PERSON] et al. [27] gave an overview of the all-solid Z-Scheme photocatalyst system, including the configuration, structure, optimization, and application of a Z-scheme photocatalyst system. [PERSON] et al. [24] presented the application of photocatalysts in air treatment, including catalyst development and reactor design. [PERSON] et al. [28] gave the latest developments and challenges in photocatalytic sterilization. Most of the current reviews focus on only one or several aspects of photocatalysts. A complete summary of the main content of photocatalysts is still missing.  
In anticipation of helping researchers with information on more efficient photocatalysts, we have summarized some common preparation and modification methods of photocatalysts. Meanwhile, a series of advances in photocatalyst technology have been reviewed to facilitate researchers' understanding of the latest research trends in photocatalysts. This review article aims to summarize researchers' efforts on the use of various preparation and modification methods to prepare ideal photocatalysts. In addition, this review also promotes the development of photocatalytic technology and even the industrialization of photocatalytic technology.