In the context of rapid urbanisation and industrialisation, traditional fossil energy fuels have been over-consumed, which has led to increasingly serious energy problems and a series of environmental issues. Hydrogen energy, which is known to us as a clean energy, is the most ideal alternative to traditional energy sources. Solar photocatalytic and photoelectrochemical water splitting to produce hydrogen is an energy conversion process that converts solar energy into chemical energy. As a new hydrogen production technology, it is undoubtedly one of the best means to solve energy and environmental problems. As one of the most researched photocatalytic materials, TiO₂ has a series of advantages such as not easy to be photocorroded or chemically corroded during the reaction, pollution-free, cheap and easy to obtain. But it also has certain disadvantages, such as a large forbidden bandwidth coefficient, the influence of its own crystalline phase, and the low utilisation of visible light, etc. In order to better solve the defects of TiO₂, this paper focuses on exploring the development of photocatalytic hydrogen-producing materials with low cost and high efficiency of hydrogen production. It reviews the photocatalytic and photoelectrochemical mechanism of TiO₂, which analyses the influence of TiO₂ itself on its own phase as well as other aspects of the limitations of the TiO₂ and also can be used to address the corresponding countermeasures for these problems. In this paper, the methods of doping metal ions, non-metal ion doping and heterojunction construction of TiO₂ semiconductor catalyst water splitting were raised in order to enhance the performance of hydrogen evolution. Doping metal and non-metal ions can inhibit the complexation of electrons and holes as a way to increase the forbidden bandwidth. Moreover, the contracting heterojunction is an effective solution to boost the performance of TiO₂ hydrogen evolution. As one of the most commonly used and optimal photocatalytic materials, TiO₂ is of great significance to explore and improve its photocatalytic efficiency. The above methods can be used to improve the photocatalytic efficiency of TiO₂. The above-mentioned methods can improve the photocatalytic efficiency of photocatalytic materials, which can help to break through a major problem in today's research, and lay a solid foundation for the rapid development of TiO₂ photocatalytic reaction technology for hydrogen production.

Keywords: TiO₂, Hydrogen evolution, Ion doping, Heterojunction construction, Water splitting.