(739c) High Throughput Study of Catalytic Surface Chemistry Over CuxAuyPd1-X-Y Alloys

A suite of tools has been developed and is now being applied for the high throughput study of catalytic surface chemistry on composition spread alloy films (CSAFs) and on surface structure spread single crystals (S⁴Cs).  

A fairly simple offset filament tools is being used for deposition of Pd_xCu_yAu_1-x-y CSAFs.  These alloys have been chosen for study because of their use as dense metal membranes for hydrogen separation and purification from coal gas.  The Pd_xCu_yAu_1-x-y CSAFs are being used as libraries for the study of surface segregation in both binary and ternary alloys.  Segregation impacts the ability of these Pd_xCu_yAu_1-x-y alloys to dissociatively adsorb hydrogen, the first step in hydrogen transport through their bulk.  X-ray photoemission spectroscopy (XPS) and low energy ion scattering (LEIS) are being used to determine the near surface and the topmost surface compositions as functions of the bulk film composition.  Surface energetics favors the segregation of Cu and Au to the alloy surfaces.  In parallel with these efforts, a multichannel microreactor has been developed for high throughput measurements of catalytic surface chemistry.  It is being used to study to composition dependence of the kinetics of H₂-D₂ exchange on the Pd_xCu_yAu_1-x-y alloys.