Research about development of photocatalyst for water oxidation reaction and carbon dioxide reduction reaction can offer enhanced photoreactivity expanded to the visible light region, which enables the commercialization due to the enhanced efficiency of the photocatalytic reaction. It also offers method for production of hydrocarbon fuels such as methane, methanol, and ethanol using water and carbon dioxide under visible light irradiation. Since the dramatic increase of the global warming gases such carbon dioxide is now becoming to give the major disastrous effects on environments for the earth, the policy to reduce these global warming gases is being considered as the most important one in international societies.
Consequently, the development of photocatalyst for carbon dioxide reduction and sustainable carbon dioxide cycle will make the leading contributions to solve these problems facing with our humanity through developing the technology to regenerate sustainable liquefied fuels and hydrogen using carbon dioxide and water with solar energy. Furthermore, the high efficiency photocatalyst also can be applied to removal of organic pollutants and hydrogen production as well as water splitting, which promote related areas of research and industrialization by providing an alternative energy sources.