Facile Solid-State Synthesis of Supported PtNi and PtCo Bimetallic Nanoparticles for the Oxygen Reduction Reaction

Proton-exchange membrane fuel cells (PEMFCs) represent an essential technology for the future decarbonization of the transportation sector. A major component of PEMFCs is the catalyst, often Pt-based alloys supported on carbon black, which are sufficiently active and stable upon long-term operation under the harsh reaction conditions implied by PEMFCs. However, the catalyst synthesis is typically laborious and challenging to upscale, employing organic solvents, surfactants, or uneconomical metal deposition routes. To solve this, we offer a mechanochemically assisted two-step solvent-less methodology to produce supported metal catalysts, particularly supported PtNi and PtCo catalysts. Accordingly, metal salts are first dispersed on the designated support by planetary ball milling. Subsequently, the mixture is reduced with hydrogen and annealed under an inert atmosphere to yield supported alloyed nanoparticles. Notably, by applying our procedure to the synthesis of carbon-supported PtNi and PtCo nanoparticles, we demonstrate that size, composition, and total metal loading can be finely adjusted, leading to highly performant catalysts in the oxygen reduction reaction (ORR).