MIET scientists figured out a way to obtain a catalyst for processing gas into alcohol
Scientists from MIET as part of a research team have proposed a new method for obtaining a material that allows processing carbon dioxide into methanol under the influence of sunlight. According to them, the new technology allows to obtain a photocatalytic material with improved properties quickly and with simple equipment. The results of the study are published in the "Nanomaterials" scientific journal.
An important direction of the development of green technologies today is the use of inexhaustible natural resources (energy of tides, winds or the sun). They are used not only to generate electricity, but also to carry out chemical processes, for which an external source of additional energy is needed.
The chemical processes occurring when the reaction system is irradiated with light are called photocatalytic. With the use of the sun's energy, photocatalysts can convert carbon dioxide into fuel (for example, methane or methanol).
Under the influence of radiation, charge carriers – electrons and holes - are generated in the catalyst material. The electron-hole pairs participate in redox reactions, converting carbon dioxide and water into other organic compounds.
Groups of scientists around the world are developing conditions under which the combination of light and the catalyst material allows for the highest yield of the reaction product at the lowest cost. Titanium dioxide TiO2 is most often used as a basis for photocatalysts due to its exceptional mechanical and optical properties, as well as low market value.
TiO2-based materials are often combined with other semiconductor materials to improve their photocatalytic properties. This stage of production is the most resource-intensive and high-tech, according to Andrey Tarasov, a researcher at the "Technology of Nanomaterials" laboratory of the National Research University "MIET".
"When two semiconductors, for example, titanium dioxide and copper oxide, are in contact with each other, a heterojunction is formed, which increases the lifespan of the charge carriers. As a result, the photocatalytic activity increases," he said.
MIET scientists in collaboration with other Russian researchers have proposed a method for forming a composite material from TiO2 and SiO by a very simple and fast method – electrophoretic deposition. This method allows to control the properties of the deposited material by controlling the composition, morphology and thickness of the formed layer.
"Imagine a magnet that attracts magnetic particles to itself. Similarly, during electrophoretic deposition, charged particles are attracted to an oppositely charged surface. In this case, not magnetic but electric lines of force make particles move in a certain direction. The particles need to have a surface charge. For example, ink in electronic books (e-ink) works on the basis of the electrophoretic phenomenon", said Larisa Sorokina, a researcher at the "Technology of Nanomaterials" laboratory.
The proposed combination of semiconductors made it possible to obtain a material with increased photocatalytic activity compared to a classical photocatalyst based on titanium dioxide. When the layers contains only 10 mass percent of copper oxide, the efficiency of converting carbon dioxide to methanol doubles, the researchers said. "Further research will focus on changing the structure of copper oxide particles by converting them into nanowires. Preliminary results show that the filamentous form of a catalytic nanomaterial may have higher photocatalytic properties compared to powder ones," Larisa Sorokina added.
Research and development of composite photocatalysts are conducted on the basis of the Institute of Advanced Materials and Technologies of MIET.