NEW-GENERATION “ELECTORNIC NOSE”

Physicists of Saratov State University for the first time demonstrated the extraordinary properties of nanoset graphene as one of the most promising materials for the manufacture of gas sensors. Now the sensors will become more sensitive to detect and recognize harmful substances. The research results are published in the scientific journal "Science and Technology of Advanced Materials".

How exactly were the new results obtained? With this question, we turned to the head of the scientific project, Chair of the Department of Radiotechnology and Electrodynamics, SSU, Doctor of Physical and Mathematical Sciences, Professor Olga Glukhova. Recall that scientists at Saratov University were the first in the world to discover optimal modes of laser synthesis of hybrid nanostructures based on carbon nanotubes and graphene. The research is carried out in accordance with the SSU development program within the framework of the federal program of the Ministry of Education and Science of Russia "Priority 2030".

Super-cells with COOH functional groups

– Olga Evgenievna, what did you find out as a result of your research?

– Nanoset graphene refers to 2D nanomaterials, which have recently been increasingly used in electronics, including such modern areas as flexible transparent electronics and electronics for personalized medicine.

As a result of extensive multidisciplinary work that combined the research of chemists-technologists synthesizing nanoset graphene and physicists identifying new properties of the material, it was found that for the formation of matrices in the form of graphene monolayers with nanoscale holes functionalized with carboxyl groups (COON), the introduction of up to 95 at is necessary. % of carboxyl groups.

For the first time, the mechanism of functionalization was theoretically revealed based on the principle of an energetically advantageous process of modification of the initial structure by certain functional groups. Using the example of functionalization by carboxyl groups of nanoset graphene, it is shown that the theoretically developed approach is fully confirmed by experimental studies. This allows us to talk about a new method of numerical modeling of the functionalization of nanostructures, which provides prediction of new nanomaterials.

The effect of carboxylation on the conduction mechanism and electronic structure is proved. Taking into account the perforated structure, lateral heterogeneity and the predominance of high-affinity carboxyls, enhanced detection and recognition of various alcohols, acetone and ammonia vapors at room temperature has been demonstrated. The chemoresistive response to ammonia in moist air was also found experimentally and justified using the density functional theory method by modeling the effect of ammonia, water and their mixture on the electronic structure and resistivity of carboxylated graphene.

– How best to explain the result of your work to a layman?

– Alcohol, acetone and ammonia vapor sensors will become much more sensitive and will be able to detect the presence of even one molecule of these harmful substances out of a million!

– How would you characterize the practical significance and applicability of the results of your work at the moment or in the future?

– All our work is aimed at increasing the sensitivity of sensor devices configured to detect alcohols and other harmful substances in the air. Such sensors will be able to warn about the appearance of harmful substances in time and prevent poisoning of people. Such devices can be in great demand not only in production, but also in everyday life. Their main goal is to preserve the health of the population.

Due to the perforated structure, high-affinity carboxylates and inherent heterogeneity in the structure and chemical composition of carboxylated graphene, it is advantageous to use it as a sensitive layer for multi-sensor chips. Selective recognition of various alcohols, acetone and ammonia at room temperature is of great importance in "electronic nose" systems, that is, electronic devices designed to detect odors or tastes. Their next generations will have reduced energy consumption and will be used not only to monitor the state of the environment, but also to diagnose diseases.

– What is the advantage and novelty of the results obtained by your group?

– Of course, we are not the only ones working in this direction. In our case, the most optimal concentration of COON groups on the surface of nanoset graphene has been found, providing improved sensory properties.

– What further tasks are facing your team?

– The results obtained showed the effect of adsorbed ammonia, water and their combination on the Fermi level and partial charge transfer. This gives a clearer idea of the nature of the chemical-resistive response of C-xy graphene, which can be extended to other functionalized graphene materials.

We plan to study in more depth the properties of mesh graphene functionalized by amino groups (NH2) in combination with nanocrystals of transition metal oxides. This should open up new perspectives in the work on the "electronic nose".

A team of physicians, physicists and technologists is engaged in the study of hybrid nanostructures based on carbon nanotubes and graphene. Part of this large team, in particular the scientific group of Saratov University, is engaged in mathematical modeling. The scientific group led by O.E. Glukhova includes eight people, including candidates of physical and mathematical Sciences, associate professors of the Department of Radio Engineering and Electrodynamics of SSU M.M. Slepchenkov, V.V. Shunaev, assistant D.A. Kolosov, as well as graduate students and undergraduates.