Combinatorial Studies of Palladium-Based Oxygen Reduction Electrocatalysts for Alkaline Fuel Cells

• Published in: Journal of the American Chemical Society 2020-02, Vol.142 (8), p.3980-3988
• Main Authors: Yang, Yao, Chen, Guanyu, Zeng, Rui, Villarino, Andrés Molina, DiSalvo, Francis J, van Dover, R. Bruce, Abruña, Héctor D
• Format: Article
• Language: English
• Subjects: catalysis (heterogeneous), electrocatalysis, hydrogen and fuel cells, charge transport, membranes, water, materials and chemistry by design, synthesis (novel materials)
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.9b13400

Hydrogen fuel cells have emerged as promising, potentially renewable energy-based, energy conversion technologies for powering electric vehicles. However, the sluggish oxygen reduction reaction (ORR) at the cathode has remained a longstanding challenge and requires the design of nonplatinum electrocatalysts with high activity and, ideally, low cost. Here, we present a combinatorial study of Pd–Cu thin-film electrodes with well-defined composition and structures, prepared by magnetron sputtering, as a fast method for assessing the ORR activity of binary alloys. This represents a facile catalyst screening method, using replaceable glassy carbon disk electrodes, which enables the rapid and reliable evaluation of ORR activity using standard rotating disk electrode (RDE) measurements. Among nine Pd–Cu alloys, Pd50Cu50 was identified as the most promising composition for the ORR and employed as a target for nanoparticle synthesis. The PdCu nanoparticles, supported on carbon, achieved a mass-specific and surface-specific activity, 3 and 2.5 times, respectively, as high as Pd/C in 1 M KOH. PdCu/C further exhibited an impressive durability with only 3 and 13 mV negative shifts in the half-wave potential after 20000 and 100000 potential cycles, respectively. The combinatorial approach guiding the nanoparticle synthesis, described herein, provides an optimized high-throughput screening method for other binary or ternary alloys as fuel cell electrocatalysts.