Direct epitaxial growth of Au nanoparticles on Pd metallene enables robust oxygen reduction electrocatalysis

Pd-based structures have been demonstrated as promising Pt-free catalysts for the oxygen reduction reaction (ORR), but suffer from undesirable structural degradation and poor durability. Herein, the direct epitaxial growth of Au nanoparticles on Pd metallene (Au@Pd metallene) is reported. The obtained heterostructure exhibits the most positive half-wave potential and the highest mass activity among all reported PdAu bimetallic catalysts for ORR and greatly enhanced stability compared to Pd metallene, with very slight mass activity decay after 10,000 cycles. This work reveals that the epitaxial heterointerfaces between Au nanoparticles and Pd metallene optimize the electronic structure of Pd and suppress Pd dissolution for enhanced activity and stability.