Abstract
Two platinum catalysts (6.3% Pt on SiO2, dispersion > 50%, designated EUROPT-1 and 0.47% Pt on Al2O3, designated PTAL) have been studied by extended X-ray absorption fine structure (EXAFS). Each Fourier transform is dominated by a single radial distance, assigned to Pt—O bonding. In EUROPT-1 the Pt—O distance is 1.94 ± 0.05 Å, slightly shorter than the Pt—O distance in βPtO2, 2.00 ± 0.02 Å. For PTAL a broad peak is observed centred at 2.00 ± 0.05 Å, which may contain a contribution due to Pt—C1 bonding. No evidence is found of metallic platinum or the Pt—Pt bonds in βPtO2. The platinum particles are thus largely amorphous, consisting of PtOx units (x⩽ 6). The comparitive ease of oxidation of small highly disperse platinum particles is discussed.

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