Strain-Driven Bimetallic-Interface Orbital Hybridization for Hydrogen Evolution Reaction.

Enforcing the bimetallic-interface orbital hybridization in single-atom catalysts (SACs) plays a critical role in determining their catalytic activity. However, the electronic state coupling among interacting sites can be affected by surficial strain, but the relative physical mechanism still needs to be understood. Herein, we propose a series of bimetallic-hybridized SACs with structural strain to disclose their interfacial charge transfer and orbital interaction, in which asymmetric superexchange interaction between adjacent Fe and Ni sites can enforce their electronic state coupling by a structural deformation. As a result, the spin-resolved electronic structure, d-band center, and Gibbs free energy can be changed by external strain, leading to a higher reactive activity. Our findings provide a new insight into understanding the contribution of surface strain to enhancing their catalytic activity.