A lamellar reverse micelle directed assembly strategy was proposed to integrate NiCo layered hydroxides (NiCoDH) nanodots and NiCo sulfide (NiCoS) nanosheets (NiCoDH/NiCoS) by one-step solvothermal method. The NiCoDH/NiCoS features with an interconnected 3D architecture composed of ultrathin amorphous NiCoS nanosheets (similar to 1.5 nm), decorated by ultra-small NiCoDH nanodots (2-3 nm). The optimal NiCoDH/NiCoS exhibits a low overpotential of 303 mV at current density of 20 mA cm(-2), together with a small Tafel slope of 77.6 mV dec(-1), the high Faraday efficiency of about 95% as well as good stability. The excellent OER performance and enhanced stability should be ascribed to the strong interface-coupling of NiCoDH nanodots/NiCoS nanosheets, highly synergistic effect of bimetal Co and Ni, amorphous-like structure to expose more active sites, and interconnected 3D architecture for effective mass transport and structural stability. This work provides a significant insight regarding the strong interface-coupling effect on OER electrocatalysis, and offers a new strategy to design highly efficient OER catalysts. (C) 2018 Elsevier Ltd. All rights reserved.