Over the past decade, advances in the colloidal syntheses of octahedral-shaped Pt-Ni alloy nanocatalysts for use in fuel cell cathodes have raised our atomic-scale control of particle morphology and surface composition, which, in turn, helped raise their catalytic activity far above that of benchmark Pt catalysts. Future fuel cell deployment in heavy-duty vehicles caused the scientific priorities to shift from alloy particle activity to stability. Larger particles generally offer enhanced thermodynamic stability, yet synthetic approaches toward larger octahedral Pt-Ni alloy nanoparticles have remained elusive. In this study, we show how a simple manipulation of solvothermal synthesis reaction kinetics involving depressurization of the gas phase at different stages of the reaction allows tuning the size of the resulting octahedral nanocatalysts to previously unachieved scales. We then link the underlying mechanism of our approach to the classical "LaMer"model of nucleation and growth. We focus on large, annealed Mo-doped Pt-Ni octahedra and investigate their synthesis, post-synthesis treatments, and elemental distribution using advanced electron microscopy. We evaluate the electrocatalytic ORR performance and stability and succeed to obtain a deeper understanding of the enhanced stability of a new class of relatively large, active, and long-lived Mo-doped Pt-Ni octahedral catalysts for the cathode of PEMFCs.
|Number of pages||13|
|Journal||ACS applied materials & interfaces|
|State||Published - 6 Jul 2022|
Bibliographical noteFunding Information:
The authors are grateful for the financial support by the Deutsche Forschungsgemeinschaft (DFG) under grant numbers HE 7192/1-2, STR 596/5-2, and STR 596/18-1. R.C. and P.S. received financial support from the European Union’s Horizon 2020 Research and Innovation Programme, Fuel Cells and Hydrogen 2 Joint Undertaking under the GAIA Project, Grant Agreement No. 826097.
© 2022 American Chemical Society.
- LaMer model
- Mo dopant
- oxygen reduction
- platinum-nickel alloy