| AVS 66th International Symposium & Exhibition | |
| Applied Surface Science Division | Thursday Sessions |
| Session AS-ThA |
| Session: | Role of Surfaces and Interfaces in Energy Material and Industrial Problems |
| Presenter: | Sarah Zaccarine, Colorado School of Mines |
| Authors: | S.F. Zaccarine, Colorado School of Mines W.W. McNeary, CU Boulder S. Shulda, National Renewable Energy Laboratory S.A. Mauger, National Renewable Energy Laboratory K. Hurst, National Renewable Energy Laboratory A.W. Weimer, CU Boulder S.M. Alia, National Renewable Energy Laboratory B.S. Pivovar, National Renewable Energy Laboratory S. Pylypenko, Colorado School of Mines |
| Correspondent: | Click to Email |
Polymer electrolyte membrane fuel cells (PEMFCs) produce electricity with only heat and water as byproducts, but sluggish kinetics of the oxygen reduction reaction (ORR) at the cathode restrict widespread commercialization, motivating development of advanced catalysts such as the extended surface platinum nickel (PtNi) and platinum nickel cobalt (PtNiCo) nanowires investigated in this work.
These catalysts were synthesized using atomic layer deposition (ALD), a scalable route that allows controlled deposition of Pt on Ni or Co nanowires. Surface and bulk composition and structure of the PtNi and PtNiCo nanowires was investigated as a function of synthesis conditions and a series of post-synthesis modifications. A variety of characterization techniques was used to gain a comprehensive understanding of structure-property-performance relationships. The catalyst was first studied using a combination of x-ray absorption near-edge structure (XANES) spectroscopy, extended x-ray absorption fine structure (EXAFS) spectroscopy, x-ray photoelectron spectroscopy (XPS), and scanning transmission electron microscopy (STEM) coupled with energy dispersive x-ray spectroscopy (EDS) hypermapping to obtain detailed complementary information about speciation and distribution of Pt and Ni, distinguishing differences between surface and bulk. Rotating disk electrode (RDE) testing was conducted to assess activity and stability of the catalysts. Differences between ALD-derived PtNi and PtNiCo samples will be discussed and compared to previously reported catalysts synthesized via spontaneous galvanic displacement (SGD). Catalysts were then integrated into membrane electrode assemblies (MEAs) and properties of the fabricated catalyst layers were investigated using STEM/EDS and transmission x-ray microscopy (TXM) to better understand the interfaces between catalyst and ionomer, with and without addition of carbon into the structure of the electrode. Our results demonstrate important advances in the performance of this class of materials achieved through optimization of surfaces and interfaces of the catalyst and catalyst layer.