How can composite catalysts improve alkaline fuel cell performance?
Chang Liu, Thomas Mallouk, and their colleagues at the University of Pennsylvania, University of Virginia, and Cornell University published recent work using their Hummingbird Scientific in-situ TEM liquid cell sample holder to investigate nanoscale Pt catalyst stability and performance in alkaline fuel cell environment. Commercial Pt-C was compared under in-situ and ex-situ scanning transmission electron microscopy (STEM) to a composite cathode with Nb-doped brookite TiO2 nanorods to lend stability to the Pt-nanoparticle catalysts.
Figures showing a) Schematic of experimental setup, showing particle dissolution rates, ion capacity, and potential difference between commercial Pt-C and Pt/Nb-TiO2. b) Liquid-phase STEM video showing Pt catalysts on Nb-TiO2 on a gold working electrode under -1.6 V applied potential, showing stability of Pt-nanoparticles over ~30 min. c) TEM image of Nb-TiO2 nanorods. d) STEM image of nanorods next to atomic model of TiO2. e) EELS elemental mapping of nanorods. f) XRD patterns for Nb-doped and undoped TiO2. g) Nb K-edge in FT-EXAFS spectra. h) High-resolution HAADF-STEM image of Pt/Nb-TiO2 with indicated area for EDS. i) EDS mapping of Pt/Nb-TiO2. Copyright © 2024 The Authors. Published by Elsevier Inc.
The liquid electrochemistry cell allowed for biasing of a three-electrode system on the microfabricated chip, at various voltages, with in situ imaging of structural changes. The composite cathode outperformed the commercial Pt-C in power density and voltage retention, effectively immobilizing the Pt-nanoparticles. A solvent residue derived from N-methylpyrrolidone (NMP) was found to play an important role in charge transfer and mass transport. The ionomer-free Nb-TiO2 catalyst support as an alternative to carbon will improve anion exchange membrane alkaline fuel cell technology.
Reference: Chang Liu, Wonil Jung, Sungho Jeon, Grayson Johnson, Zixiao Shi, Langqiu Xiao, Shengsong Yang, Cheng-Yu Chen, Jun Xu, Cherie R. Kagan, Sen Zhang, David A. Muller, Eric A. Stach, Christopher B. Murray, and Thomas E. Mallouk. Cell Rep. Phys. Sci. 5 (7) 102090 (2024). DOI: 10.1016/j.xcrp.2024.102090
Full paper Copyright © 2024 The Authors. Published by Elsevier Inc.
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