Formation of Catalytically Active Nanoparticles under Thermolysis of Silver Chloroplatinate(II) and Chloroplatinate(IV)

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Abstract

The thermal behaviour of Ag2 [PtCl4 ] and Ag2 [PtCl6 ] complex salts in inert and reducing atmospheres has been studied. The thermolysis of compounds in a helium atmosphere is shown to occur in two stages. At the first stage, the complexes decompose in the temperature range of 350–500C with the formation of platinum and silver chloride and the release of chlorine gas. At the second stage, silver chloride is sublimated in the temperature range of 700–900C, while metallic platinum remains in the solid phase. In contrast to the thermolysis of Ag2 [PtCl6 ], the thermal decomposition of Ag2 [PtCl4 ] at 350C is accompanied by significant heat release, which is associated with disproportionation of the initial salt to Ag2 [PtCl6 ], silver chloride, and platinum metal. It is confirmed by DSC measurements, DFT calculations of a suggested reaction, and XRD. The thermolysis of Ag2 [PtCl4 ] and Ag2 [PtCl6 ] compounds is shown to occur in a hydrogen atmosphere in two poorly separable steps. The compounds are decomposed within 170–350C, and silver and platinum are reduced to a metallic state, while a metastable single-phase solid solution of Ag0.67Pt0.33 is formed. The catalytic activity of the resulting nanoalloy Ag0.67Pt0.33 is studied in the reaction of CO total (TOX) and preferential (PROX) oxidation. Ag0.67Pt0.33 enhanced Pt nano-powder activity in CO TOX, but was not selective in CO PROX.

Original languageEnglish
Article number1173
JournalMolecules
Volume27
Issue number4
DOIs
Publication statusPublished - 1 Feb 2022

Keywords

  • CO PROX
  • Platinum
  • Silver
  • Solid solution of metals
  • Thermolysis

OECD FOS+WOS

  • 1.04 CHEMICAL SCIENCES
  • 1.06.CQ BIOCHEMISTRY & MOLECULAR BIOLOGY

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