Electrosynthesis of Porous Cu-Based Metal-Organic Framework and Its Nanocomposite with p-Type Conductive Polymer as a Novel Electrode Material for Highly Capacitive Pseudocapacitors

Metal–organic frameworks (MOFs) are a new member in the vast field of porous materials. MOFs are attracting considerable attention because of their unique structural properties, such as high surface areas, tunable pore sizes, and open metal sites, which enable them to have potential applications in gas storage, catalysis, sensors, drug release, and separation [1,2]. Several preparation methods for the formation of MOFs have been developed throughout the years such as hydro- and solvothermal, ionothermal, microwave assisted, sonochemical, electrochemical, and mechanochemical syntheses [3,4]. Among the common methods to prepare of MOFs, the mechanochemical method is a most promising technique due to its simple procedure, ease of handing, high yield efficiency, high purity of products and very short reaction time. In this work, we have electrosynthesized Cu(btec)0.5DMF (H4btec = 1,2,4,5- benzenetetracarboxylate acid) on the surface of graphite electrodes by applying a constant voltage to the solution of H4btec, metal ions and NaNO3. The electrosynthesized Cu(btec)0.5DMF was characterized by X-ray diffraction and scanning electron microscopy. Furthermore, POAP/ Cu(btec)0.5DMF nanocomposite film has been synthesised by using a simple and general strategy namely in situ electropolymerization on the surface of the working electrode. Different electrochemical methods including galvanostatic charge–discharge experiments, cyclic voltammetry and electrochemical impedance spectroscopy are carried out in order to investigate the performance of the system. The electrochemical behavior shows that the POAP/Cu(btec)0.5DMF composites possess excellent electrochemical stability with 91% of its initial capacitance retained after 1000 charge/discharge cycles. The enhancement of electrochemical performance of the POAP/Cu(btec)0.5DMF composite originate from the high specific surface area of Cu(btec)0.5DMF. 220 Therefore, Cu(btec)0.5DMF has an obvious improvement effect, which makes the composites have more active sites for faradic reaction and larger specific capacitance than pure POAP.