Alloyed Pt–Zn Oxygen Reduction Catalysts for Proton Exchange Membrane Fuel Cells

Abstract

Better oxygen reduction catalysts are needed to appreciably increase the efficiency of proton exchange membrane fuel cells. In this work, high-activity Pt−Zn alloy catalysts were prepared using two distinct synthetic approaches. The first�where Zn was introduced to Pt nanoparticles via atomic layer deposition�led to a 30% increase in Pt-mass-normalized fuel cell activity. Density functional theory calculations elucidated the origin of this enhancement and motivated the preparation of an alloy with increased Zn content. To this end, a fabrication technique leveraging Zn electroplating was employed to prototype a second Pt−Zn alloy with a rotating disk electrode (RDE). The higher-dosed structure (∼19 at. % Zn) delivered exemplary activity (MA = ∼3 A/mg Pt ), but the synthetic approach was not amenable to membrane electrode assembly (MEA) fabrication. An Arrhenius analysis was carried out to project the hypothetical catalytic enhancement under fuel cell operating conditions. This exercise introduced a discussion on the reduced activity observed in MEAs relative to the benchtop RDE setups used more ubiquitously for catalyst evaluation.

Atomic-scale engineering of advanced catalytic and energy materials via atomic layer deposition for eco-friendly vehicles

“…Besides the sequentially deposition of Pt and metal, ALD of Pt and metal oxide in combination with a subsequent reduction step was also performed to prepare Pt alloys. For instance, Pt 3 Ti and PtZn alloy nanoparticles were synthesized by reducing Pt and TiO 2 or ZnO at different temperature, the average sizes of which were ∼10 nm and ∼3 nm, respectively [198,199]. As shown in figure 9(b), Chen et al recently reported a strategy to construct uniform sub-3 nm Pt-based intermetallic nanocrystals based on selectively ultrathin metal oxide coating on Pt nanoparticles via ALD [200].…”

Synergistic Effect of Oxygen Vacancy-Rich SnO2 and AgCl in the Augmentation of Sustained Oxygen Reduction Reaction

“…Commercialization of DMFC is influenced heavily by the geometrical and economic constraints in producing Pt-based catalysts. Moreover, Pt- and Pt-alloy-based catalysts are prone to catalytic poisoning, which limits the performance of DMFCs. , Selectivity of the cathode catalyst toward ORR is essential in the event of methanol crossover, which is the crossing of unreacted methanol from the anode compartment to the cathode compartment through the membrane. The presence of methanol in the cathode compartment results in a mixed potential if the cathode catalyst is not methanol tolerant or ORR selective.…”