Controllable one step electrochemical synthesis of PANI encapsulating 3d-4f bimetal MOFs heterostructures as electrode materials for high-performance supercapacitors

Abstract

Two new 3-dimensional (3D) 3d-4f bimetal organic frameworks (ZnCe-MOF and CuCe-MOF) were created through hydrothermal method. These MOFs have the similar formula (M2(imidazole)2Ce(H2O)(C2O4)1/2(4,5-ida)2·2(H2O), M = Zn, Cu; 4,5-ida: 4,5-imidazole dicarboxylate) and possesses monoclinic symmetry in the P21/n space group. The electrodeposition method was used to in-situ coat polyaniline (PANI) to improve the electrical conductivity. As the electrode materials for supercapacitors in three-electrode system, the specific capacitance of CuCe-MOF@PANI-1 and ZnCe-MOF@PANI-1 electrodes can reach 724.4F g−1 and 713.2F g−1 at 1 A g−1. Using the as-synthesized CuCe-MOF@PANI-1 heteorostructure as positive material, the assembled hybrid capacitor delivers an energy density of 87.45 Wh kg−1 and 58.05 Wh kg−1 at power density of 850 W kg−1, demonstrating that the heteorostructure of MOF coated with PANI has promising applications in portable energy storage devices.