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 Li 2 O 2 . As a result, the uniformly distributed amorphous film-like Li 2 O 2 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.