Herein, porous Co3O4-CoO heterostructured nanosheets are constructed by plasma treatment. The density-functional theory calculations demonstrate that constructing Co3O4-CoO heterostructures modify the electronic structure to achieve enhanced electrical conductivity, but also boost the charge transfer to realize enhanced surface reactivity. Contributing to the short ion diffusion path, the rich electroactive surface sites and enhanced charge transfer capability, the resulting Co3O4-CoO nanosheet arrays possess the low overpotential of 270 mV at 10 mA cm(-2) and the low Tafel slope of 49 mV dec(-1). This work provides a novel strategy to construct heterostructured nanosheet arrays by surface reorganization for costeffective OER electrocatalyst. (C) 2020 Elsevier Inc. All rights reserved.