Recent advances in visible light-driven water oxidation and reduction in suspension systems

In order to solve the shortage of sustainable energy and the related concern about combustion of fossil fuels, converting the most abundant solar energy into chemical fuels becomes one of the most promising choices to provide the everlasting and environmentally friendly energy vector along with the minimum impact on environment. Among the methods of converting solar energy into chemical fuels, there is a significant interest in the renewable hydrogen production by photocatalysts from abundant water under visible light irradiation. Therefore, the development of efficient photocatalysts for water reduction and oxidation in a suspension system is the footstone for the development of solar energy conversion. In this review, the fundamental theory of photocatalysis and key factors affecting photocatalysis will be introduced first. Then the new materials development covering inorganic materials (oxides, nitrides and sulfides), carbon-based photocatalysts, and semiconductor-coordination compound photocatalysts developed over the past 10 years will be addressed with discussion about dominating factors in the photochemical process. This review would provide a comprehensive reference to exploring the efficient and novel materials working for the solar energy conversion to affordable and sustainable fuels. Finally, the perspective of the technology is also discussed.