SYNTHESIS OF METAL NANOPARTICLES AND THEIR ALLOYS USING SUPERCRITICAL FLUIDS

Recently, proton-conducting oxides have been intensively studied in connection with the possibility of their use in various electrochemical devices (fuel cells, separators and hydrogen sensors, etc.). In particular, LaNbO₄ lanthanum orthoniobate is a perovskite ABO₃ c structure and has a mixed ion-electron conductivity, which has a proton conductivity of the order of 10-³ Om-¹ cm-¹ at temperatures above 700°C and high stability in a humid and enriched CO₂ environment. These materials are promising for the creation of membranes for the separation of oxygen and medium temperature solid oxide fuel cells. But studies have shown that lanthanum orthoniobates have insufficient electronic conductivity. One approach to solving this problem is to create nanocomposite materials based on them using metals and their alloys. Optimization of the composition, microstructure and texture of such materials will improve the characteristics of fuel cells and membranes. In this work, nanoparticles of metals and their alloys NiCuO_x, CoCuO_x, NiCoAgO_x in the presence of isopropyl alcohol in a supercritical medium were first synthesized. The morphology and particle size of the alloys was studied using electron microscopy JSM-6460 LV (JEOL, Japan), and the phase composition was studied on a BrukerAdvance D8 diffractometer using CuKα. The results of the study showed that using supercritical alcohols allows one to obtain metals and alloys in one stage. According to TEM, the obtained powders after calcination are almost spherical nanoparticles with an average size of 25-45 nm. The obtained bimetallic powders are promising materials for the preparation of composites and deposition on a porous substrate to create proton-conducting membranes.

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