Formation of Dispersed Particles of Tungsten Oxide and Deposition of Platinum Nanoparticles on Them Using Organometallic Precursors from Solutions in Supercritical Carbon Dioxide

A one-pot synthesis of dispersed platinum-tungsten composites has been developed. Initially, using tungsten hexacarbonyl as a precursor in solution in supercritical CO2 in the presence of oxygen as an oxidizer promoting thermal decomposition of the precursor, dispersed particles of tungsten oxide with a grain size of about 100 nm and an aggregate size of 200-500 nm have been synthesized. Then, these dispersed particles have been used as a substrate for the subsequent deposition of platinum nanoparticles, which includes two stages: (1) forming a film of an organometallic precursor by deposition from a solution in supercritical CO2 and (2) thermal decomposition of the precursor. Two types of platinum precursors, the dimethyl(1,5-cyclooctadiene)platinum and platinum hexafluoroacetylacetonate, which are both soluble in supercritical CO2, are typically used in the practice of similar studies. The size of the platinum nanoparticles formed using the former and latter precursors are 2.3 +/- 0.7 nm and 3.5 +/- 0.8 nm, respectively. The composites obtained are characterized by a relatively narrow size distribution of the noble metal nanoparticles and their uniform distribution over the surface of the particles of the dispersed carrier. Such materials may be of interest for (electro)catalysis tasks.