It is of great importance to design and exploit high-efficiency low-costelectrocatalysts for the oxygen evolution reaction (OER) under mild conditions for applications. In this Article, we propose that formation of a thin amorphous Ni carbonate layer on Ni3N nanoarray supported on carbon cloth (Ni3N NA/CC) is an effective strategy to boost its OER activity in at near-neutral pH. When used as a 3D non noble-metal OER electrocatalyst, the resulting core-shell Ni3N@Ni-Ci NA/CC displays superior catalytic activity with extremely small overpotential of 400 mV for 20 mA cm(-2) in 1.0 M KHCO3 (bulk pH: 8.3). Moreover, it also exhibits considerable long-term electrochemical durability with its activity being preserved for at least 12 h. Conductive Ni3N nanoarray not only provides as the Ni source for in-situ electrochemical derivation of 3D Ni-Ci catalyst with high surface area, more exposed active sites and facilitated mass diffusion, but effectively prompts the electron transport from Ni-Ci shell to CC, enabling more efficient water oxidation electrocatalysis. (C) 2017 Elsevier Inc. All rights reserved.