A photocatalytic reaction can directly convert solar energy to chemical energy in order to produce hydrogen and oxygen by decomposing water using the energy provided by sunlight. Therefore, research concerning photocatalytic reactions has grown as energy and environmental problems have become increasingly serious.
There have been many studies on photocatalytic reactions, and this has recently become a very active area of research because of demands for reducing the usage of fossil-fuel-based energy. In order to compete with other energy sources, hydrogen must be produced efficiently at a low cost. Conventional photocatalytic materials such as TiO2, however, can only utilize ultraviolet light, which comprises only 3% to 4% of the available solar energy. Therefore, the conversion efficiency of water to hydrogen is low when solar energy is used in this process.
WO3 is a potentially good visible-light-response photocatalytic material, although tungsten is expensive and not an abundant element. In contrast to these drawbacks, the raw material graphite-type carbon nitride (g-C3N4) is cheap and abundant in nature; hence, it is expected to be a next-generation photocatalytic material.
g-C3N4 can represent a solution to the aforementioned environmental problems because it can efficiently produce hydrogen by utilizing solar energy and because it may be used to further hydrogen-based energy as a next-generation energy. If large amounts of hydrogen can be produced efficiently at a low cost by utilizing sunlight and water, which are both sustainable and natural resources, then we may no longer need to depend on the usage of fossil-fuel-based energy sources such as petroleum oil and coal.
g-C3N4 is an organic-type semiconductor photocatalytic material that does not contain metal. It has been reported to produce hydrogen and oxygen under visible light by combining with other appropriate chemicals. g-C3N4 is chemically and thermally stable and can be synthesized at a low cost. Because it possesses a unique ability to respond to visible light, researchers are also attempting to apply g-C3N4 as an electrochemical and fluorescent imaging material.
By combining g-C3N4 with an appropriate metal complex, such as metal oxide, metal nitride, or organic materials such as black phosphine, CO2 may be reduced and valuable substances such as formic acid or CO may be synthesized under normal temperature and pressure conditions. This may be regarded as an artificial photosynthetic reaction. This is the first time in the world that the synthesis of g-C3N4 has been achieved and commercialized.
SOURCE Green Science Alliance Co., Ltd.