The effect of non-spherical platinum nanoparticle sizes on the performance and durability of proton exchange membrane fuel cells

Abstract

Platinum (Pt) nanoparticles with different sizes of 2 nm and 5 nm supported on functionalized high surface area carbon (HSC) have been successfully synthesized with a one-pot synthesis technique in large scale. Of the interest for the proton exchange membrane fuel cell applications, the synthesized supported catalysts are evaluated by physical characterizations, half-cell and scaled up single cell tests to study the impact of the catalyst sizes on cell performance and durability. Physical characterizations clearly demonstrate the sizes, shapes, crystallinity phases, and the total loading of the Pt nanoparticles on HSC. Half cell characterizations demonstrate higher electrochemical surface area, higher mass activity, and less durability for the working electrode prepared by the smaller Pt nanoparticle sizes (2 nm) than the larger Pt nanoparticles (5 nm). Scaled up single cell tests using air and hydrogen as the cathode and anode reactants demonstrate the membrane electrode assembly (MEA) prepared by smaller Pt nanoparticle sizes (2 nm) shows the maximum power density of 1.1 W/cm2, which is 7% higher than the maximum power density of MEA prepared by larger Pt nanoparticles (5 nm) under similar operational conditions. The 30,000 cycles of accelerated stress test on the membrane electrode assembly prepared by larger Pt nanoparticles (5 nm) demonstrates 13% drop at maximum power density, illustrating the excellent performance against degradation (ageing).