Nanostructures with nonprecious metal cores and ultrathin precious metal shells are promising catalysts for many electrochemical reactions, including oxygen reduction reaction (ORR) and methanol/ethanol oxidation reaction (MOR/EOR), as they can enhance precious metal efficiency through core/shell interfacial strain and ligand effects. However, core/shell interaction within a real catalyst is complex and due to the presence of various interfaces in all three dimensions is often oversimply interpreted. We start with an example of Co2P/Pt core/shell nanorods to demonstrate the importance of synthesizing nanocrystals with well-designed and well-tailored core/shell interfaces. Through density functional theory (DFT) calculations, we found that forming Co2P(001)/Pt(111) interface could greatly improve Pt energetics for ORR, while Co2P(010)/Pt(111) would be highly detrimental to ORR catalysis. We developed a seed-mediated approach to core/shell Co2P/Pt nanorods (NRs) within which Co2P(001)/Pt(111) interface was selectively expressed over the side facets and the undesired Co2P(010)/Pt(111) interface was minimized. The resultant Co2P/Pt NRs were highly efficient in catalyzing ORR in acid, superior to benchmark CoPt alloy and Pt nanoparticle catalyst. Then this strategy was extended to other one-dimensional (1D) core/shell nanostructures with nonprecious element cores to enable their applications in MOR and EOR. The relevant theoretic calculation, materials synthesis and structural/catalytic characterization will be discussed.

One-dimensional core/shell nanocrystals with favorable interfacial synergy for electrocatalysis

2019 Fall National Meeting

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