Paper SS-TuA11
Alloy Surface Reactivity on Cu_xAu_yPd_1-x-y Composition Spread Alloy Films

Tuesday, November 1, 2011, 5:20 pm, Room 109

The key features of Cu-Au-Pd alloys relevant to their application as hydrogen purification membranes are the ability to dissociatively adsorb H₂ and the ability to transport H atoms through their bulk. We have developed tools for the preparation of Cu_xAu_yPd_1-x-y composition spread alloy films (CSAFs) as libraries for high throughput study of their catalytic surface properties. These ternary Cu_xAu_yPd_1-x-y CSAFs expose a broad and continuous distribution of compositions for spatially resolved analysis of their properties. Electron backscatter diffraction has been used to verify the structure of the films across their composiiton spread and to demonstrate that they have the atomic structure expected on the basis of their phase diagram. LIES has been used to study surface segregation as a continuous function of composition, (x,y), demonstrating that segregation is preferred in the order Au>Cu>Pd at the clean alloy surfaces. A multichannel microreactor array has been used to spatially resolve the surface activity for H₂ dissociation by measuring the kinetics of H₂-D₂ exchange as a function of alloy composition. This reveals that while both Cu and Au poison surface activity, Cu is more effective than Au at supressing H-D exhange activity. This work demonstrates the potential value of CSAFs as platforms for study of alloy surface chemistry and for comprehensive study of their properties across composition space.