Facet-Orientated Pd Core Impels Quasi-Monolayer Pt Shell To Boost the Oxygen-Reduction Electrocatalysis

Abstract

Pd core (Pdc) supported quasi-monolayer Pt shell (Ptqms) can efficiently utilize noble-metal Pt in the electrocatalytic oxygen-reduction reaction (ORR). Here, we report that the facet orientation of Pdc is tuned for impelling Ptqms to boost the ORR electrocatalysis. Facet-orientated Pdc is achieved by the cyclic-voltammetry treatment, which restructures Pdc to form the typical (111)-facet exposure. The (111)-facet-orientated Pdc induces the moderately compressed Ptqms, exhibiting over 4-fold specific activity and near 9-fold mass activity in the ORR than commercial carbon-supported Pt nanoparticles (TKK, 2.1 nm). The volcano-type relationship between the Pt–Pt bond distance and ORR activity of Ptqms demonstrates the strain control of electrocatalytic activity and also predicts the optimal strain of 2.695 Å. These findings pave the way for developing highly efficient PdcPtqms ORR electrocatalysts.