(341f) Solid State Chemistry Mass Production of Platinum Group Metal Catalysts with Tailored Particle Morphology

Catalytic property of platinum group metal (PGM) nanoparticles can be altered significantly by the nature of facets exposed. For example, Pt (100) plane excels in activity/selectivity compared to other planes in many reactions, including ring-opening hydrogenation of pyrroles, benzene hydrogenation, methanol oxidation (MOR), and electro-oxidation of ammonia (AOR). Pt-Ni (111) surface can exhibit exceptionally high activity towards oxygen reduction reaction (ORR) for polymer electrolyte membrane fuel cells (PEMFCs). The findings have stimulated the exploration of new methods for preparing PGM catalysts with tailored particle morphology, because the usage of PGMs and thus the cost can be largely decreased. However, to date, there have been no feasible methods for cost-effective and mass production of the shaped PGM catalysts.

We realize mass production of PGM catalysts with tailored particle morphology by developing a robust, green, and low-cost solid state chemistry approach. A variety of shaped PGM catalysts, including cubic Pt/SiO₂, cubic Pt/C, tetrahedral Pd/C, octahedral Pt-Ni/C, and cubic Pt-Cu/C, have been demonstrated for preparation. The experiments suggest that the formation of shaped PGM nanoparticles is resultant of employing both CO and H₂ gases, wherein H₂ aids transportation and reduction of the metal precursors on support and CO is responsible for the particle morphology formation. The prepared octahedral Pt_1.5Ni/C catalyst exhibits high ORR activities of 3.99 mA/cm² Pt and 1.96 A/mg Pt at 0.90 V vs. RHE, which are about 20 and 10 times the values for commercial Pt/C specifically. The cubic Pt/C catalyst shows 1.44 mA/cm² at 0.6 V vs. RHE in AOR, which is five times that of 0.30 mA/cm² using commercial Pt/C.