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. (C) 2020 Elsevier Inc. All rights reserved.