Atomic Structure of Au Nanoparticles on a Silica Support by an X-ray PDF Study

We investigated the atomic structure of gold nanoparticles with an average size of ∼5 nm in diameter, supported by silica. We used high-energy X-ray diffraction and the atomic pair distribution function (PDF) to probe the local atomic structure. Measurements were performed from 25 to 950 °C. The structure is approximately fcc in average but exhibits small distortions. The structural distortion increases with the temperature and could be related to the catalytic activity of gold nanoparticles. Above 425 °C, rapid particle growth and coalescence were observed.