Near-surface study of structure-property relationships in electrochemically fabricated multi-component catalysts

• Main Author: Rettew, Robert E.
• Published: Georgia Institute of Technology 2013
• Subjects: Nanofilm; Electrodeposition; Redox replacement; SLRR; Platinum; XPS; Catalysis; X-ray absorption; Surface chemistry; Electrocatalysis; Thin films
• Online Access: http://hdl.handle.net/1853/45841

This work outlines a series of developments and discoveries related to surface chemistry of controlled near-surface architectures. Through a combination of various X-ray spectroscopy techniques and innovative electrochemical fabrication techniques, valuable knowledge has been added to the fields of electrochemical fabrication, electrocatalysis, and fundamental surface chemistry. Described here is a specific new development in the technique of surface limited redox replacement (SLRR). This work, along with an accompanying journal publication1, reports the first-ever use of nickel as an intermediary for SLRR. In addition, this work identifies specific deviations from the nominal reaction stoichiometry for SLRR-grown films. This led to the proposal of a new reaction mechanism for the initial stages of the SLRR process, which will assist future fabrication attempts in this field. This work also discovered fundamental changes in Pt overlayer systems as the thickness of the overlayer on a gold support is increased from less than a single atomic monolayer to multilayer thicknesses. It was found that Pt overlayers below a certain threshold thickness exhibited increased affinity for hydroxyl groups, along with an increased propensity for formation of oxide and chloride species. These films were also studied for methanol, carbon monoxide, and ethylene glycol electro-oxidation. Finally, this work reports controlled surface architectures of Pt and Cu deposits on application-oriented TiO₂ nanotube arrays and Au-carbon supports.