Strained heterointerfaces in sandwich–like NiFe layered double hydroxides/Co1-xS for highly efficient and superior long–term durable oxygen evolution reaction

Sandwich–like NiFe layered double hydroxides/Co1-xS (NiFe LDH/Co1-xS) heterostructure with synergistic electrocatalytic effects for highly efficient oxygen evolution reaction is successfully prepared by electrodepositing Co1-xS on the surface of NiFe LDH grown on nickel foam (NF). The NF supported heterostructure possesses three-dimensional (3D) catalytic space and strained heterointerface. Thereinto the Co1-xS layer provides extra active sites over the original NiFe LDH. Besides, the lattice mismatch in the surface of NiFe LDH induces the formation of lattice strain in Co1-xS, which thus modulates the local electronic structures. Density functional theory (DFT) calculations validate that the strained heterointerface has advantageous OER activity. From the results of electrochemical tests, the NiFe LDH/Co1-xS possesses large number of active sites and fast charge transfer. More importantly, optimized structure and interface characteristics improve the electrocatalytic stability, resulting in long–term durability with almost no attenuation after 150 h constant current test.