Dual Tuning of Ultrathin α‑Co(OH)₂ Nanosheets by Solvent Engineering and Coordination Competition for Efficient Oxygen Evolution

Large-scale preparation of ultrathin 2D Co-based nanosheets is of great importance in the fields of catalysis, energy conversion, etc. Herein, we have developed a simple preparation method of 2D ultrathin α-Co­(OH)₂ nanosheets by mixing an aqueous solution of Co salt and a methanolic solution of 2-methylimidazole at room temperature. The resulting α-Co­(OH)₂ materials are nanosheets with an average thickness of ∼2.5 nm and the size in micrometers. Benefiting from the ultrathin thickness, this α-Co­(OH)₂ nanosheet exhibits excellent oxygen evolution reaction performance with an overpotential of 267 mV at <i>j</i> = 10 mA cm^–2. This strategy can be applied to prepare other 2D Co-based layered double or triple hydroxides. Therefore, this work provides new strategies to prepare a series of 2D hydroxide nanosheets with solvent engineering and coordination competition.