(689a) Characterization of Isolated Pt Atoms on Anatase TiO2
In this study, we have employed comprehensive characterization methods to compare isolated Pt atoms and nanoparticles anchored on anatase TiO2. Aberration-corrected HAADF-STEM images clearly reveal isolated Pt single atoms dispersed on the TiO2 surface. We used FTIR to monitor the changes in vibrational frequency of the CO adsorbed on Pt SACs and Pt nanoparticles. Our in situ EXAFS results also provide evidence of SACs by monitoring the Pt-Pt coordination to determine the spatial location of isolated Pt atoms and Pt nanoparticles. We further conducted in situ near ambient pressure XPS that demonstrated that the Pt single atoms are stable at 250 °C upon exposure to 1.5 Torr H2 due to the full coordination of Pt with O on TiO2; in contrast, Pt nanoparticles were progressively reduced under the same condition. We provide computational insights into the stability of the catalyst.