Breaking Scaling Relations by Bimodal Strain in Mixed-Phase Hybrid Intermetallic Nanocrystals.

Abstract

Catalytic performance of heterogeneous catalysis is inherently limited by the linear scaling relations of normalized binding energies among the adsorbed intermediates. Breaking this limitation would create opportunities in the development of high-performance catalysts. To this end, we propose a framework for breaking the scaling relations by evoking bimodal strain over the Pt catalyst in a model structure dictated by Pt-coated Pt₃Zn-PtZn mixed-phase hybrid nanocrystals. Such a hybrid heterostructure simultaneously introduces compressive and tensile strain over the Pt shell arising from distinct interfacial interactions between the Pt shell and Pt₃Zn/PtZn intermetallic nanodomains. The bimodal strain allows concurrently facilitated consecutive bond cleavage reactions against O-H and C-H groups in formic acid electro-oxidation, which are bridged by fast surface diffusion of formate species across the Pt surface with minimized energy barrier. The mixed-phase hybrid heterostructure outperforms similar Pt-terminated monophase nanocrystals accommodating unimodal strain of either compressive or tensile types and breaks the well-established activity versus strain volcano relationship.