Ligand-induced growth of Co/Cu bimetallic metal organic frameworks with different morphology for energy storage†

Abstract

The morphological structure is of particular importance to the energy storage properties of metal organic framework (MOF) electrode materials. Herein, a series of Co/Cu bimetallic MOFs were achieved by the facile hydrothermal method of cobalt nitrate and copper nitrate with phthalic acid (PA), terephthalic acid (TPA) and isophthalic acid (IPA). Co/Cu–IPA MOF, prepared by the reaction between cobalt nitrate, copper nitrate and IPA ligand, exhibits a loose lamellar structure while Co/Cu–PA MOF and Co/Cu–TPA MOF display a thin-strip structure. Co/Cu–IPA MOF displays a high specific area of 375.8 m² g⁻¹ compared with Co/Cu–PA MOF (44.09 m² g⁻¹) and Co/Cu–TPA MOF (9.64 m² g⁻¹). Besides, Co/Cu–IPA MOF possesses more Cu⁺ content. Therefore, Co/Cu–IPA MOF shows a high specific capacitance of 369.1 F g⁻¹ at 1 A g⁻¹. A Co/Cu–IPA MOF//AC asymmetric device was constructed successfully. This device shows an energy density of 6.81 W h kg⁻¹ at a power density of 500 W kg⁻¹.