1650 hydrogen molecules per hour
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The Novosibirsk scientists have proposed a new efficient method for synthesis of a highly active photocatalyst for hydrogen production under the action of sunlight. The materials developed are porous "sponges" made of graphite-like carbon nitride with platinum nanoparticles. The system showed one of the highest values of photocatalytic activity, among all known analogues, with a low content of noble metals, the Russian Science Foundation says.

The photo is sourced from rupec.ru

“We have high hopes for solar energy, and hydrogen can be used as fuel there. The energy density of this environmentally friendly gas is high, exceeding the one of diesel by six times and that of gasoline by 12 times. The approach we develop within the project combines these two promising areas, namely the method of photocatalytic production of hydrogen from water under the action of visible light,” said Ekaterina Kozlova, the Project Leader, Doctor of Chemistry, Professor of the Russian Academy of Sciences, the leading researcher of the G.K. Boreskov Institute of Catalysis SB RAS.

Previously, there was not enough effective and at the same time stable photocatalyst. The staff of the G. K. Boreskov Institute of Catalysis SB RAS and their colleagues from the Nikolayev Institute of Inorganic Chemistry SB RAS have solved this problem.

The method turned out to be quite simple. The scientists made a porous carbon nitride base by thermal decomposition of melamine cyanurate, the complex widely used in the chemical industry, in which two organic acids are connected by hydrogen bonds. This material is a catalyst itself; the matter is its semiconducting properties. Under the action of sunlight, there are formed electron-hole pairs in it, which enter into chemical transformations with the molecules adsorbed on the material surface. However, the semiconductor would work much better if a co-catalyst, such as platinum, were applied to it, as the chemists did in this work.

This approach made possible obtaining of a system with the highest “turnover rate” of hydrogen production among all currently known photocatalysts – 1650 gas molecules generated by a single platinum atom per hour.

This can be explained by a simultaneous favourable combination of several factors: a large specific surface area together with a uniform distribution of metal nanoparticles and the developed pore system. In addition, the catalyst turned out to be quite stable, and its crystal structure and chemical composition practically did not change after reaction, which is due to the peculiarities of the platinum location in the porous base: the metal nanoparticles spontaneously adsorbed around the defects and at the edges of the carbon nitride layers. As a result, a chemical reaction took place in these very areas.

“We have also assembled a photocatalytic demonstration plant, for which we still have to select the optimal composition of the reaction mixture. The results obtained will serve as a scientific basis for creation of prototypes of the devices for hydrogen production under the action of sunlight. In fact, the approach under development can be considered in the future as the basis for development of solar hydrogen energy,” the report quotes E. Kozlova.


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May 2022