Abstract:
The world's total primary energy consumption was about ~ 6.2 x 1020 J in 2023 and it is expected to reach double by 2050. On the other hand, about 80% of today's total energy supply originates from fossil fuels (e.g. petroleum, gas and coal) that are major responsible for air and water pollution. In addition, these non-renewable energy sources are discharging a large amount of CO2 in the environment after their combustion which creates severe problems such as global warming and climate changes. Therefore, it is an urgent need to develop renewable energy technologies and resources that neither rely on fossil fuels nor emit carbon dioxide for safer society and sustainable growth. Photocatalysis as a surface phenomenon is one of the most important advanced oxidation processes (AOP) is a promising and environmental-friendly method that applies in various industrial wastewater treatment. Most of semiconductors use as photocatalysts in these processes face challenges like low optical absorption, insufficient charge carrier separation and electron-hole recombination. After a brief history and introduction on principles of semiconductor photocatalysis, physics and technology of different nanostructures (0D, 1D and 2D) and novel 2D materials as semiconductor photocatalysts are presented. Several strategies on materials design and optimization of photocatalysts and influencing factors on photocatalytic reactions will be described. Then three types of photocatalytic reactions for clean energy production and environmental remediation namely i) photoelectrochemical (PEC) water splitting towards hydrogen generation, ii) photocatalytic degradation of major wastewater pollutants such as dyes and drugs and iii) CO2 reduction to value-added products, will be briefly introduced. Then, role of surfaces/interfaces of photocatalysts in improving reaction yield under visible light and UV photoirradiation as well as kinetics and mechanism of the reactions will be summarized. Finally, recent advances and prospects of semiconductor photocatalysts will be presented.