Solar energy is arguably the most abundant and readily available energy source in nature. Among them, photocatalyst hydrogen production technology is one of the solar energy applications. Through the catalyst, the sun can split water, produce hydrogen and oxygen, and finally use hydrogen for fuel cells. The promising green hydrogen production option, but the realization of this technology is not an easy task, because the photocatalyst material is difficult to find, the technology is still in the laboratory stage.
However, Oxford University in the UK has made a breakthrough in photocatalyst research recently, and is expected to find a new generation of green energy hydrogen production materials. According to the paper "Applied Physics Letters", scientists at Oxford University discovered that in addition to being used in solar cell technology, the halide double perovskites may also be a good water-decomposition material.
Feliciano Giustino, a professor of materials at Oxford University, said that if effective photocatalyst materials can be proposed, this will be a major breakthrough for the team.
Research teams from various countries have tested a variety of photocatalyst materials, such as gallium phosphide, gallium arsenide or titanium dioxide, but the results have not been as expected. At present, scientists can use titanium dioxide to split sunlight into water. Unfortunately, the material cannot effectively absorb visible light, and the light conversion efficiency cannot be further improved. Therefore, no photocatalyst material has reached commercial application.
In order to identify potential materials, the Oxford University team used supercomputers to calculate the quantum energy states of the four halides of double perovskites, and found that double perovskites Cs2BiAgCl6 and Cs2BiAgBr6 are photocatalyst forces, and both materials have better visible light absorption capabilities than titanium dioxide. If it is better, it can also generate electrons and holes, and have enough energy to carry out the redox reaction, and then achieve the decomposition of water to produce hydrogen and oxygen.
Giustino said that few materials have these functions at the same time. Although the team was unable to package tickets to say that this must be a very effective material, these compounds seem to possess all the characteristics of a photocatalyst.
Accidentally found other applications of perovskite
It was an accident to find this photocatalyst material. The Giustino team was originally looking for solar cell materials, and found that this type of perovskite can also be used in photocatalysts.
In recent years, scientists have realized the application potential of perovskite in solar photovoltaics, and its conversion efficiency has also increased by 6 times in 9 years. At present, many research teams have combined silicon and perovskite through cascade design to greatly improve the photoelectric conversion efficiency. However, perovskite batteries contain lead. If they are used in large-scale solar power plants, leaded solar cells may be harmful to the environment. Therefore, scientists began to use computer simulation to find alternative materials in 2016, and then developed new lead-free perovskites.
The Oxford team research pointed out that in addition to having good photoelectric conversion potential, these materials can also be used in photocatalysts. George Volonakis, a postdoctoral researcher in the Department of Materials at Oxford University, said that the new double perovskite can not only be used in tandem solar cells, but also has great potential for development in the field of photocatalysis.
However, the current analysis only has a theoretical basis. The team's next step is to study whether these materials can be as predicted and can be effective in reality. The researchers will also use computer computing technology to test whether the double perovskite material can be used for light sensing. And other applications.
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