| AVS 63rd International Symposium & Exhibition | |
| Applied Surface Science | Wednesday Sessions |
| Session AS-WeA |
| Session: | Multiple Technique Approaches for Real-World Industrial Problem Solving |
| Presenter: | Svitlana Pylypenko, Colorado School of Mines |
| Authors: | S. Shulda, Colorado School of Mines C. Ngo, Colorado School of Mines S. Alia, National Renewable Energy Laboratory J. Nelson Weker, SLAC National Accelerator Laboratory B. Pivovar, National Renewable Energy Laboratory S. Pylypenko, Colorado School of Mines |
| Correspondent: | Click to Email |
Transition metal nanowires are emerging as an effective structure for various heterogeneous catalysis applications. Metal and metal oxide nanowires have demonstrated high activity for the oxidative coupling of methane into higher value products, hydrogenation of aromatic compounds, and water splitting, among others. Of particular interest is the application of platinum-nickel and platinum-cobalt nanowires as oxygen reduction catalysts in polymer electrolyte membrane fuel cells (PEMFCs) as they have shown activities that significantly surpass the current state of the art Pt nanoparticles supported on high surface are carbon and are considered a promising alternative. The activity and durability of Pt nanowires is dependent on both the surface and bulk properties, which continuously evolve during different steps of the synthesis, electrode preparation, and fuel cells operation, making a multi-technique analysis approach necessary.
High surface area platinum nickel (PtNi) nanowires have been synthesized via spontaneous galvanic displacement. Various post-processing treatments were applied altering the chemistry and structure of the nanowires to improve their activity and durability. This work focuses on the analysis of the surface and bulk composition and structure and their evolution with various treatments. X-ray photon spectroscopy (XPS), energy dispersive x-ray spectroscopy (EDS) via transmission electron spectroscopy (TEM), x-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) spectroscopies, and transmission x-ray microscopy (TXM) were utilized. All of the processing treatments altered the surface chemistry and in some instances the morphology of the nanowires, with some treatments resulting in increased activity and durability while others being detrimental to the performance. The extensive characterization of the nanowires pre- and post-processing provided a robust understanding of each treatments effect on the nanowires and guided the optimization of the post-processing treatments. Moreover, this study highlights the challenges associated with the characterization of nanowires structures, where evolution of both surface and bulk composition and structure are extremely important.