Construction of dendritic Pt–Pd bimetallic nanotubular heterostructure for advanced oxygen reduction

Abstract

Compositions and morphologies of Pt-based electrocatalysts have great impact on the electrocatalytic activity and stability of oxygen reduction reaction (ORR). Herein, we report a novel design of one-dimensional (1D) Pt–Pd dendritic nanotubular heterostructures (DTHs) by controlling the degree of Pt²⁺-Pt reduction reaction and Pd-Pt galvanic replacement reaction with uniform Pd nanowires as sacrificial templates. The obtained Pt–Pd bimetallic DTHs catalyst exhibited uniform and dense Pt dendritic nanobranches on the surface of 1D hollow Pt–Pd alloy nanotubes, possessing superior catalytic activity for ORR compared to state-of-the-art commercial Pt/C catalysts. Typically, the Pt₄Pd DTHs catalyst showed efficient mass activity (MA, 1.05 A mg_Pt⁻¹) and specific activity (SA, 1.25 mA cm_Pt⁻²) at 0.9 V (vs. RHE), and the catalyst exhibited high stability with 90.4% MA retention after 20 000 potential cycles. The Pt–Pd bimetallic DTHs configuration combines the advantages of 1D hollow nanostructures and dense Pt dendritic nanobranches, which results in rich electrochemical active surface sites, fast charge transport, and multiple dendritic anchoring points contact on carbon support, thus boosting its catalytic activity and stability towards electrocatalysis.