Multi-scale exploring the output performance mechanism in MEA with high intrinsic activity PtCo intermetallic compounds

摘要

Intermetallic compounds offer the high activity of alloy catalysts with greatly improved alloy stability, making them a promising replacement for commercial Pt/C. However, few studies have focused on their catalytic properties in practical applications. Herein, the PtCo intermetallic compounds are adopted as substitutes for commercial Pt/C to explore their practical application and deeply analyze the catalytic mechanism by combining multi-scale research methods. Experimental results indicate that PtCo intermetallic compounds can increase the maximum power density up to 863.2 mW cm-2 in membrane electrode assembly, 20.2 % higher than commercial Pt/C under the loading of 0.15 mgPt center dot cm- 2 in the cathode. The membrane electrode assembly with PtCo intermetallic compounds exhibits high activity at high potentials while preemptively encountering concentration polarization. The introduction of transition metals not only reduces the limiting step energy barrier but also reduces the adsorption force of reactants on the activity sites, increasing the resistance of oxygen transport. The catalytic layer of PtCo intermetallic compounds exhibits higher current density inhomogeneity compared to Pt/ C, this will limit the utilization of highly active catalysts and reduce membrane electrode assembly durability. This phenomenon can be effectively relieved by adjusting the operating conditions.

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