Volatilization Behavior of Supported Au Nanoparticle Arrays under H₂ at High Temperature

The fabrication and experimental study of model Au nanoparticle arrays (nanodots) were used to allow a direct comparison of reactive evaporation at elevated temperatures and nonambient H₂-containing gas atmospheres with theoretical models. Strong temperature and H₂-concentration dependencies were confirmed as expected, and the observed dependence in particle diameter with time was effectively described using a reactive evaporation and gas phase diffusion based quantitative model. Deviations from model expectations for a monolithic film of Au due to nanoparticulate structure were effectively captured by accounting for both (1) the reduced effective surface area of Au on the substrate surface and (2) the enhanced partial vapor pressure of Au-containing species in the vapor phase due to surface energy effects. The approach described here is broadly applicable to the quantitative study of stability in noble and precious metal nanoparticles and thin films for sensing and catalytic applications in harsh environmental conditions.