Adjusting the d-band center of metallic sites in NiFe-based Bimetal-organic frameworks via tensile strain to achieve High-performance oxygen electrode catalysts for Lithium-oxygen batteries

Developing effective electrocatalyst and fundamentally understanding the corresponding working mechanism are both urgently desired to overcome the current challenges facing lithium-oxygen batteries (LOBs). Herein, a series of NiFe-based bimetal-organic frameworks (NiFe-MOFs) with certain internal tensile strain are fabricated via a simple organic linker scission strategy, and served as cathode catalysts for LOBs. The introduced tensile strain broadens the inherent interatomic distances, leading to an upshifted d-band center of metallic sites and thus the enhancement of the adsorption strength of catalysts surface towards intermediates, which is contributed to rationally regulate the crystallinity of discharge product Li2O2. As a result, the uniformly distributed amorphous film-like Li2O2 tightly deposits on the surface of strain-regulated MOF, resulting in excellent electrochemical performance of LOBs, including a large discharge capacity of 12317.4 mAh g-1 at 100 mA g-1 and extended long-term cyclability of 357 cycles. This work presents a novel insight in adjusting the adsorption strength of cathode catalysts towards intermediates via introducing tensile strain in catalysts, which is a pragmatic strategy for improving the performance of LOBs.