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In this paper, we report a new modified solution combustion synthesis technique for one-step production of metallic Co nanoparticles. The main unique feature of our approach is the use of microwave-assisted foam preparation. Also, the effect of different types of fuels (urea, citric acid, glycine, and hexamethylenetetramine) on the combustion process and characteristics of resultant solid products were investigated. It was shown that the combination of microwave-assisted foam and hexamethylenetetramine as a fuel allows us to produce metallic Co nanoparticles with the broad size distribution (∼5-40 nm), high coercivity (370 Oe), and high value of saturation magnetization (137 emu/g) by the one-step solution combustion synthesis under normal air atmosphere without any post reduction.

Graphene (G) and metal-decorated G nanocomposites are among the most promising materials for a wide variety of practical applications, and, therefore, the development of fast and reliable methods for nanocomposite synthesis is an important task. Herein we report the new fast approach for solution combustion synthesis (SCS) of large-area G−metallic nanocomposites in an air atmosphere. The G-based nanocomposites were obtained by a SCS using copper and nickel nitrates, as well as their stoichiometric mixture as the metal source and citric acid as a fuel and carbon source. The G structures started on the catalytic surface of freshly synthesized metallic nanograins during the combustion process and formed large-area freestanding films due to the high-energy and fast synthesis process. We proposed a mechanism of formation of the G-based nanocomposites. The phase compositions, structural features, and magnetization behavior of G@Cu, G@Ni, and G@CuNi nanocomposites are carefully studied and described. G@metal nanocomposites were studied as a material for the creation of a highly effective sensing element of semiconductor gas sensors.

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A spray solution combustion synthesis method has been developed to produce hollow spherical metal nanostructured particles. In this approach, combustion reactions in the liquid solution contribute 100% of the overall energy released during the synthesis process without the involvement of an external gaseous flame. It has been shown that this method is effective for the synthesis of spherical hollow particles of metals (Ni, Cu) with an average diameter of about 3 μm and wall thicknesses of about 20 nm.

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In this work, we studied possibility to obtain bimetallic nanopowders by our modified solution combustion synthesis method using citric acid as a fuel. Stoichiometric amounts of metal nitrates with metal to metal ratios 1:1 and 1:2 and fuels with final oxidizer to fuel ratio of 1.75 were used as initial components to prepare aqueous solutions. The almost complete absence of metal oxide phases was confirmed by energy-dispersive X-ray spectroscopy. The X-ray diffraction analysis of obtained materials showed that all samples are pure bimetallic nanopowders with distorted cubic crystal structure of each metal. According to high resolution transmission electron microscopy the mean diameter of metallic particles are about 10 nm for all nanopowders. The calculated interplanar distances of crystals of metal particles as well as detailed scanning transmission electron microscopy studying showed uniform distribution of different metal spices into nanoparticles. Thus, we can conclude the nanopowders are bimetallic particles with co-integrated crystal structures of different metalic spices. We suppose, the possibility of solution combustion synthesis of bimetallic nanopowder in the air environment is due to a combination of type and amount of the fuels as well as technological conditions of the synthesis. These lead to rapid combustion process at low temperature. In addition, protective inert atmosphere appears above freshly synthesized metal nanopowders during thermal decompositions of the fuels that eventually prevent metal oxidation. Modified SCS method could be successfully used for one-step synthesis of complex oxide-oxide and metal-oxide core-shell nanostructures. For citation: Romanovskii V.I., Khort A.A., Podbolotov K.B., Sdobnyakov N.Y., Myasnichenko V.S., Sokolov D.N. One-step synthesis of polymetallic nanoparticles in air invironment. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 42-47