SPbGASU teacher Maxim Polyakov, candidate of chemical science, talks about the use of 3D carbon materials
Maxim Polyakov
Senior Lecturer of the SPbGASU Department of Building Physics and Chemistry Maxim Polyakov, Candidate of Chemical Science, conducts research on the structural and functional properties of 3D materials based on carbon nanotubes (CNTs). In his opinion, the creation of nanostructured three-dimensional carbon structures with controlled density and architecture is one of the fundamental tasks of nanotechnology and a necessary step for the emergence of new generation functional carbon materials based on carbon. These materials can be used as active layers of chemiresistive gas sensors.
– “I have been studying the properties of materials based on carbon nanotubes for about five years. In 2019 he defended his Ph.D. thesis on "Structural features and sensory properties of mesogenic phthalocyaninates, their hybrid and composite materials with carbon nanotubes.” Combining two substances into a new hybrid material, studying the properties of this material is an extremely relevant direction. In 2018, a grant from the Fund for Fundamental Research was received for this topic,” says Maxim Polyakov.
– What goals did you set for yourself?– My colleagues from Novosibirsk and Turkey and I planned to obtain new hybrid materials based on carbon nanotubes and polyaromatic molecules and to compare the properties of the obtained substances with each other. We wanted to create a combined, or hybrid, material with increased conductivity, because carbon conducts current well. This can be quite useful, as it allows the use of cheaper instruments for measuring conductivity, since higher accuracy is required to measure high-resistance materials, which makes the measuring instrument more expensive. In addition, based on a comparative analysis of our data (detection limit, thermal stability, sensor lifetime, sensitivity, and selectivity), films of hybrid materials that have the best sensory properties will be selected, which will subsequently provide an opportunity to select the most suitable materials for creating sensor devices.
– What did you find out during the research?– In the course of experiments, we studied resistive sensory properties - that is, the change in the conductivity of a substance when it comes into contact with a gas. The measured quantity was the conductivity of the material, which changes during the interaction of the hybrid material film with a gaseous substance (NH3, H2, H2S, CO2). As the experiment showed, when gas is puffed in, a sharp increase in the resistance of the material occurs, which indicates the presence of a sensory response to this gas. It is important that when purging with clean air, the resistance returns to its original values, and this indicates reversibility of the sensory response. The use of a hybrid material made it possible to increase the magnitude of the sensory response by more than ten times compared to the response of the initial carbon nanotubes.
Fig.1. Scheme of obtaining a hybrid material using single-wall carbon nanotubes and molecules of axially substituted silicon photalocyaninate IV
Fig. 2. Time dependence of the relative response R / R0 when feeding 1–50 ppm ammonia at a relative humidity of 5% and a temperature of 25°С; b - dependence of the response of the SWCNT / SiPc sensor and initial CNTs on the ammonia concentration
In addition to measuring the magnitude of sensory response and its reversibility, it is important to study how these characteristics are affected by temperature and humidity. We have conducted such studies and published the results. Another improvement of the experiment was the possibility of studying the selectivity of the response with the simultaneous introduction of two or more gases. We investigated the selectivity using the example of gas mixtures ammonia / carbon dioxide, ammonia / hydrogen sulfide, hydrogen / carbon dioxide, hydrogen / hydrogen sulfide.
– Where are the results of your research published??
– Earlier this year, the journal Applied Surface Science published an article describing the preparation and sensory properties of a material based on CNTs and coumarin molecules. And the Molecules journal " (ed. MDPI), indexed in Scopus, published an article "Hybrid material for chemoresistive sensors based on single-walled carbon nanotubes and axially substituted silicon phthalocyaninate IV".– How, in your opinion, chemistry differs from other sciences? In what direction will it develop?
– In a broad sense, chemistry surrounds us everywhere - any object consists of substances, and substances are in the field of close attention of chemists. For example, less than a hundred years have passed since man learned to make artificial polymers, which do not exist in nature, so that polymers would become firmly established in everyday life, and today it is difficult to do without them (plastics, rubbers, nylon, and many others). This is the merit of chemistry. After all, this is not just the processing of natural raw materials, their purification, enrichment, etc.; it is the creation of completely new substances, the study of their properties and the use of these properties for the benefit of man. Chemistry is a very broad scientific field to single out one line of development. I see that research is currently underway in the field of nanoobjects, a wide variety of hybrid and functional materials, in the field of biochemistry and pharmaceuticals.
– Could you please share your future plans?
– I would like to continue my scientific work on the electrophysical study of the properties of organic semiconductors in a wide range of parameters. A deep understanding of the conduction mechanisms of molecular organic semiconductors will serve as a prerequisite for their wider application in the field of sensing.Text: Tatyana Petrova
Photo: Sergey Klishis
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