Monitoring of Pt Nanoparticle Formation by H2 Reduction of PtO2: An in Situ Dispersive X-ray Absorption Spectroscopy Study

In situ dispersive X-ray absorption spectroscopy (DXAS) measurements were used to monitor the Pt nanoparticle formation by hydrogen reduction of PtO2 at 150 degrees C. The kinetics of the reduction process, as well its dependence on the percentage of H-2 in the reductive gas mixture, was investigated. The results reveal that a complete reduction of the PtO2 was obtained using a gas mixture with 55% of H-2 in the time of 20 min, resulting in nanoparticles with an estimated mean diameter of 2.8 nm. In addition, the in situ DXAS investigation of the H2S sulfidation of the formed Pt nanoparticles at 150 degrees C revealed a low degree of sulfidation, in opposition to the Pt-Pd bimetallic systems.