Rare earth-rich sublayer tuned Pd-skin for methanol and CO tolerance oxygen reduction and hydrogen oxidation reaction

Abstract

Storing hydrogen in green methanol is a well-known and cost-effective way for long-term energy storage. However, using green methanol in fuel cell technologies requires electrocatalysts with superior resistance to poisoning induced by intermediate species. This study introduces a new class of palladium-based rare earth (RE) alloys with exceptional resistance to methanol for the oxygen reduction reaction (ORR) and outstanding resistance to carbon monoxide poisoning for the hydrogen oxidation reaction (HOR). The PdEr catalyst achieved unparalleled ORR activity amongst the Pd-based rare earth alloys and demonstrated remarkable resistance to methanol poisoning, which is two orders of magnitude higher than commercial Pt/C catalysts. Furthermore, the PdEr catalyst shows high hydrogen oxidation activity under 100 ​ppm CO. Comprehensive analysis demonstrates that the RE element-enriched sublayer tuning of the Pd-skin's surface strain is responsible for the enhanced ORR and HOR capabilities. This modification allows for precise control over the adsorption strength of critical intermediates while concurrently diminishing the adsorption energy of methanol and CO on the PdEr surface.