Segregation and CO-induced reconstruction of Pd in AuPd bimetallic catalyst was studied using a 2-dimensional model system where various amounts of Pd were deposited onto a Au(111) single crystal. Combining infrared reflection absorption spectroscopy (IRRAS), scanning tunneling microscopy (STM) and density functional theory (DFT) calculations, we aim reaching a better understanding of the dynamics of Pd segregation and CO-induced reconstruction in the Pd/Au(111) system. STM results show that as-deposited Pd atoms form islands at low coverages (0.3 ML). After annealing, a surface alloy is formed that implies high surface roughness (Fig. 1a). Pd tends to segregate to the subsurface and this is investigated by STM and IRRAS. CO pressure stabilizes Pd back on the surface by forming both Pd monomers and dimers/trimers at high Pd coverages (&gt;0.38 ML), while only forming Pd monomers at coverages of 0.1 ML. By conducting temperature-programmed IRRAS (TP IRRAS), apparent activation energy of Pd dissolution to Au in the presence of CO can be determined to be 0.48 eV (Fig. 1b and 1c).

Surface science study of segregation and CO-induced reconstruction on bimetallic AuPd catalysts

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.