Cobalt hydroxide in alpha-form (a-Co(OH)(2)) is an attractive electrocatalyst for oxygen evolution reaction (OER). Traditional preparation of alpha-Co(OH)(2) nanosheets often leads to a packing morphology after synthesis or post electrode fabrication, which severely limits the exposure of surface active sites. In this work, we report the synthesis of a self-supported 3D flower-like structure consisting of 2D alpha-Co(OH)(2) nanosheets through a metal-organic-framework (MOF)-mediated synthetic method. We found that the formation of MOF intermediates can produce dispersive alpha-Co(OH) 2 nanosheets with a stable 3D hierarchical structure which can effectively avoid the packing of individual nanosheets. The developed alpha-Co(OH)(2) nanosheets exhibit an obviously enhanced OER activity in comparison with the nanosheets prepared with traditional method. The prepared alpha-Co(OH)(2) nanosheets have been well characterized and their formation mechanism is proposed. (C) 2018 Elsevier Ltd. All rights reserved.