Solar energy is the most abundant and readily available source of energy in nature. Among them, photocatalyst hydrogen production technology is one of solar energy applications. It uses the catalyst to let the sun break down water, produce hydrogen and oxygen, and finally use hydrogen for fuel cells. Promising green hydrogen production options, but the implementation 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, the University of Oxford recently made a breakthrough in photocatalyst research, and is expected to find a new generation of green energy hydrogen production materials. According to the "Applied Physics Letters" paper, Oxford University scientists found that the halide double perovskites (halide double perovskites) can be used in addition to Solar cell technology may also be a good water-decomposing material.
Feliciano Giustino, a professor of materials at the University of Oxford, said that if an effective photocatalyst material could be proposed, it would be a major breakthrough for the team.
National research teams have so far tested a variety of photocatalyst materials, such as gallium phosphide, gallium arsenide or titanium dioxide, but the results are not as good as expected. Scientists can now use titanium dioxide to let sunlight break down water, but unfortunately the material can not effectively absorb visible light. The light conversion efficiency cannot be further improved, so no photocatalyst material has yet reached commercial applications.
In order to find potential materials, the Oxford University team used supercomputers to calculate the quantum energy states of the four halides, and found that the double perovskites Cs2BiAgCl6 and Cs2BiAgBr6 are the photocatalysts. The visible light absorption capacity of both materials is better than that of titanium dioxide. If it is better, it can also generate electrons and holes, and have enough energy to carry out redox reaction, and then achieve water decomposition to produce hydrogen and oxygen.
Giustino said that very few materials have these functions at the same time. Although the team can't pack the ticket saying that this must be a more effective material, these compounds seem to possess all the characteristics of the photocatalyst.
Unexpected discovery of 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 noticed the potential of perovskite in solar photovoltaics, and its conversion efficiency has increased six-fold in 9 years. At present, many research teams have combined silicon and perovskite through tandem design to greatly improve photoelectric conversion efficiency. However, perovskite batteries contain lead. If used on a large scale in solar power plants, leaded solar cells may harm the environment. Therefore, in 2016, scientists began to use computer simulation to find alternative materials to develop new lead-free perovskites.
Oxford team research pointed out that in addition to good photoelectric conversion potential, these materials can also be used in photocatalysts. George Volonakis, a postdoctoral researcher at the University of Oxford's materials department, said that the new double perovskite can be used not only for tandem solar cells, but also in the field of photocatalysis. Has a very large development potential.
However, the current analysis only has a theoretical basis. The next step for the team is to study whether these materials can be as predictive and can be effective in reality. Researchers will also use computer computing technology to test whether dual perovskite materials can be used for light sensing. Applications such as devices.
