A joint research group of Tokyo Institute of Technology, University of Tsukuba, Kochi University of Technology, and the University of Tokyo has found that a hydrogen borohydride sheet consisting of boron and hydrogen releases hydrogen only by light irradiation at normal temperature and pressure.This will make it possible to achieve explosive hydrogen transport much more safely than conventional methods that require high temperatures and pressures.
The hydrogen borohydride sheet, also known as borophane, was successfully synthesized by our researchers for the first time in September 2017.Since it is a two-dimensional substance in which the light elements boron and hydrogen are combined in a composition ratio of 9: 1, the mass hydrogen density is extremely high at 1%, and it can be applied as a lightweight and safe hydrogen carrier to replace the high-pressure hydrogen gas bomb that has an explosion risk. It has been expected.
In this study, we predicted that electron transition from the bonding orbital of boron to the antibonding orbital of hydrogen would occur at the energy corresponding to ultraviolet rays by first-principles calculation.In other words, the research group thought that hydrogen bonds would be weakened only by irradiation with ultraviolet rays and hydrogen would be generated, and analyzed the gas released from the borohydride sheet using a light source.
As a result, as expected from the first-principles calculation, it was confirmed that hydrogen was generated by irradiation with ultraviolet rays, and in addition, it was found that the amount of hydrogen produced was as much as 8% of the mass of the borohydride sheet.
Even organic hydrides such as cyclomethylhexane, which have been regarded as promising hydrogen carriers, have a mass hydrogen density of only 6.2%, and hydrogen release requires heating at 300 ° C or higher.On the other hand, the borohydride sheet can extract an extremely large amount of hydrogen compared to the existing hydrogen carriers under mild conditions of room temperature and atmospheric pressure by a simple operation of irradiating with ultraviolet light.
In the future, as a safe, lightweight, and simple portable hydrogen carrier, it is expected to be applied to in-vehicle fuel cells currently equipped with a high-pressure hydrogen tank.
Paper information:[Nature Communications] Photo induced hydrogen release from hydrogen boride sheets
