Biaxially Compressive Strain in Ni/Ru Core/Shell Nanoplates Boosts Li-CO 2 Batteries.

Regulating surface strain of nanomaterials is an effective strategy to manipulate the activity of catalysts, yet not well recognized in rechargeable Li-CO 2 batteries. Herein, biaxially compressive strained nickel/ruthenium core/shell hexagonal nanoplates (Ni/Ru HNPs) with lattice compression of ≈5.1% and ≈3.2% in the Ru {10-10} and (0002) facets are developed as advanced catalysts for Li-CO 2 batteries. It is demonstrated that tuning the electronic structure of Ru shell through biaxially compressive strain engineering can boost the kinetically sluggish CO 2 reduction and evolution reactions, thus achieving a high-performance Li-CO 2 battery with low charge platform/overpotential (3.75 V/0.88 V) and ultralong cycling life (120 cycles at 200 mA g -1 with a fixed capacity of 1000 mAh g -1 ). Density functional theory calculations reveal that the biaxially compressive strain can downshift the d-band center of surface Ru atoms and thus weaken the binding of CO 2 molecules, which is energetically beneficial for the nucleation and decomposition of Li 2 CO 3 crystals during the discharge and charge processes. This study confirms that strain engineering, though constructing a well-defined core/shell structure, is a promising strategy to improve the inherent catalytic activity of Ru-based materials in Li-CO 2 batteries.