Regulation of the shell thickness and shell components in PtCu/PdCu core–shell tripods for ethylene glycol and glycerol oxidation reactions

Abstract

Bi-component core–shell catalysts constructed from both noble and transition metals have been widely used in alcohol oxidation reactions, especially the introduction of transition metal components that can improve the anti-poisoning ability of core–shell catalysts. However, excessive amounts of non-precious metal components can show leaching characteristics in electrocatalytic tests, thus hindering the durability of the catalyst. In this work, we report a simple strategy based on seed-mediated growth to synthesize PtCu/PdCu core–shell tripod nanocrystals (TDNs). The construction of PdCu shells with different thicknesses and the modulation of the low Cu content in the shells are achieved via the galvanic replacement reaction between Pd and Cu as a feasible mitigation strategy. PtCu/PdCu TDNs with different shell thicknesses and Cu fractions in the shell exhibit various catalytic activities in ethylene glycol and glycerol oxidation. The PtCu/Pd₄₂Cu core–shell TDNs with a shell thickness of about 1.3 nm exhibit significantly high catalytic activities towards the ethylene glycol oxidation reaction (EGOR) and glycerol oxidation reaction (GOR), due to the unique structure of the branched TDNs and stable PdCu shell. Both the specific and mass activities for the EGOR and GOR on PtCu/Pd₄₂Cu TDNs are an order of magnitude higher than those of commercial Pt/C and Pd/C. Moreover, this synthetic strategy is not restricted to PtCu/PdCu TDNs, and it can be extended to PtCu/MCu (M = Rh, Ru, Au, Ir) heterostructure TDNs. The present work could provide a simple and effective strategy for the design and regulation of multi-component core–shell catalysts.