PNNL

Abstract

Nanostructured gold catalysts have attracted increasing interest since the pioneer work of Haruta which demonstrated unusually high catalytic activities for CO oxidation when the nanoparticles were made less than ~10 nm diameter in size and supported on oxides. It is possible to use core-shell gold nanoparticles to construct the catalyst and activate the catalytic activity by applying a thermal-treatment process. The understanding of how the core-shell surface components reconstitute in such a catalytic activation process will have important implications in expanding this approach to the design and fabrication of nanostructured catalysts. We report herein the results of a study of decanethiolate-capped gold nanoparticles of 2-nm and 5-nm core sizes assembled on planar substrates using 1,9-nonanedithiol (NDT) and 11-mercaptoundecanoic acid (MUA) as molecular linkers were studied as a model system. XPS and IR are employed to detect the identity of surface species and to analyze the elemental composition or oxidation states of the nanomaterials, from which we derive structural information about the surface reconstitution of the core-shell nanostructured catalysts. Electrochemical methods are used to characterize the electrocatalytic activities.