Article

Post-Synthesis Characterization of PtNi Nanowires for Enhanced Durability and Efficiency

Surface Analysis Spotlight: XPS

by Cesar Saucedo XPS Scientist

Hydrogen is poised to become a dominant energy carrier, essential for building a sustainable, low-carbon energy system. Achieving this goal requires the development of new technologies to produce, store, and utilize hydrogen in ways that are cost-effective, sustainable, and high performing. Polymer electrolyte membrane fuel cells (PEMFCs) present a promising solution for generating clean electricity with minimal environmental impact. However, the slow kinetics at the fuel cell cathode require effective catalysts to generate electricity effectively. Previous research has explored the synthesis of extended-surface platinum-nickel (PtNi) nanowires (NWs) through atomic layer deposition (ALD) and assessed their durability.¹

In this poster, we investigate how the composition and chemical states of these nanowires evolve following a series of post-synthetic modifications aimed at maximizing their longevity as catalysts. Auger Electron Spectroscopy (AES) is noted for its high-resolution imaging and elemental mapping, confirming the preservation of the nanowire structure after the removal of the nickel (Ni) core and providing detailed insight into the distribution of Ni and platinum (Pt) on the surface. In addition, X-ray Photoelectron Spectroscopy (XPS) and Hard X-ray Photoelectron Spectroscopy (HAXPES) were used to analyze the chemical composition at different depths, with XPS focusing on the surface and HAXPES probing the subsurface, both important regions for catalytic activity. These techniques together revealed surface oxidation of Ni, an increased concentration of Pt near the surface after acid leaching, and a predominance of metallic nickel in the subsurface.

For more information on how AES, XPS, and HAXPES can be used to develop a more complete model of the complex chemical nature of these catalysts, please attend the AVS 70th International Symposium & Exhibition where Dr. Cesar Saucedo will present a poster on "Post-Synthesis Characterization of PtNi Nanowires for Enhanced Durability and Efficiency.”

[1] Zaccarine, S. F., Alia, S. M., McNeary, W. W., Chattot, R., Dzara, M. J., Martens, I., Mauger, S. A., Weimer, A. W., Drnec, J., Pivovar, B. S., & Pylypenko, S. (2022). Optimization of Extended-Surface PtNi Nanowire Oxygen Reduction Electrocatalysts Produced via Atomic Layer Deposition. ACS Applied Energy Materials, 5(4).