Anion-exchange membrane fuel cells are promising to reduce cost by employing non-precious metal cathode catalysts, however, more efficient anode catalysts are needed to improve the sluggish hydrogen oxidation reaction in alkaline electrolytes. Here, we report that BCC-phased PdCu alloy nanoparticles, synthesized via a wet-chemistry method with a critical thermal treatment, exhibit up to 10-fold HOR improvement in both mass and specific activities, compared with the FCC-phased PdCu counterparts. In-situ HE-XRD characterization reveals that low annealing temperature favors formation of a PdCu fcc structure, but at higher annealing temperatures, the bcc structure dominates PdCu NPs. HOR activity of PdCu catalyst can be attributed to bcc phase dominance. Density functional theory (DFT) computations further unravel the enhanced HOR activity on the bcc structure PdCu NPs originates from contributions from both H and OH adsorption. With the incorporation of Cu, the PdCu catalyst exhibits much weaker hydrogen adsorption strength than that on Pd surface. The PdCu fcc and bcc surfaces possess very similar H binding strength, however, the PdCu bcc surface features much stronger OH binding as compared to that on PdCu fcc surface, which is closer to that on the most HOR active Pt model surfaces. Therefore, the PdCu-bcc phase exhibits much higher HOR activity than its fcc counterpart due to synergistic optimization of both H and OH binding strength. This work might open a new route to develop efficient HOR catalysts from the perspective of crystalline structure transformation.

BCC-phased PdCu nanoparticles as a highly active electrocatalyst for hydrogen oxidation reaction in alkaline electrolytes

2019 Spring National Meeting

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