Preparation Of Two-dimensional ?-d Conjugated MOFs Based Flexible Transparent Electrode For Energy Storage Application

Flexible transparent supercapacitors(FTSCs)have been developed as a kind of energy storage devices for powering smart portable electronic devices.The two-dimensional(2D)conductive metal organic frameworks(2D c-MOFs)with?-d conjugated structure have the advantages of large specific surface area,high active sites and fast ion transmission,which have great research values and application potentials in the field of FTSCs.At present,there are few reports on the construction of2D c-MOFs flexible transparent conductive electrodes(FTCEs)with mechanical flexibility,excellent photoelectric performance and capacitive properties.FTCEs based on inorganic nanomaterials or carbon materials lack low diffusion resistance and abundant active sites during the rapid charge and discharge process.Therefore,the fabrication of FTCEs with high-areal capacitance and excellent rate characteristics has become a research focus and difficulty in the field of FTSCs.Hence,the development of porous active materials with high conductivity and specific surface area is of great significance.In order to solve these problems of FTCEs,in this thesis,2D c-MOFs films with abundant active sites are designed and prepared,and further applied in the field of flexible transparent devices.The electrodes possess excellent flexibility,high capacitance,transparency and remarkable rate characteristics.The specific content is as follows:1.Research on the preparation and application of Cu₃(HHTP)₂ FTCEs2D Cu-MOFs FTCEs have been designed and constructed to solve the problem that is difficult for FTCEs to have good flexibility,capacitance and transparency.2D Cu₃(HHTP)₂ MOFs film(HHTP=2,3,6,7,10,11-hexahydroxytriphenylene)was synthesized on the substrate by a layer-by-layer self-assembly method,and Cu₃(HHTP)₂ FTCEs were successfully prepared.In this system,the transmittance(T)and sheet resistance(R_s)of the film can be adjusted through adjusting the number of layers and controlling the thickness to coordinate the photoelectric and capacitive properties of FTCEs.Due to the large-areal interconnected conductive framework and ultra-thin structure,the 2D Cu₃(HHTP)₂ MOFs film exhibits low internal resistance,high specific surface area and abundant active sites,which is conducive to achieve the rapid ion transmission and efficient ionization,adsorption/desorption and redox charge transfer.In addition,the reversible redox structure of 2D Cu₃(HHTP)₂ MOFs film is formed by the coordination reaction of HHTP organic ligand and Cu²⁺metal center,which is beneficial to increase the specific area capacitance,energy/power density,cycle life and further improve the electrochemical pseudocapacitance performance.Cu₃(HHTP)₂ is a kind of promising electrode materials for FTCEs,which provides a guidance for the construction of 2D c-MOFs film for flexible and transparent energy storage devices that integrate excellent mechanical flexibility,good capacitance properties and optoelectronic properties.2.Research on the preparation and application of Ni₃(HITP)₂ FTCEsThe porous Ni-MOFs with high conductivity and specific surface area are used as electrode materials to solve the problem of low rate characteristics of FTCEs.The nano-scale Ni₃(HITP)₂ MOFs(HITP=2,3,6,7,10,11-hexaaminotriphenylene)film was prepared by a simple gas-liquid interface method,and the thickness of the film is controllable.Using the van der Waals interaction between the interfaces,the film was transferred to a flexible transparent substrate by the Langmuir-Sch(?)fer(L-S)method,and Ni₃(HITP)₂ FTCEs were successfully prepared.In this system,Ni₃(HITP)₂ MOFs films have the advantages of nano-scale thickness,excellent electrical conductivity and high porosity,which endow Ni₃(HITP)₂ FTCEs with the synergy of low diffusion resistance and high ion accessibility.Therefore,Ni₃(HITP)₂ FTCEs exhibit excellent area capacitance and high rate characteristics,and the corresponding symmetric/asymmetric FTCEs have excellent energy storage properties and excellent cycle stability.It shows that FTSCs based on 2D c-MOFs films have good application prospects.