Zuo Jinglin and Ding mengning of Nanjing University have made important progress in the study of the conductive mechanism of two-dimensional organometallic frame materials

Recently, Professor Zuo Jinglin, Professor Ding mengning and Professor LAN Yaqian of Nanjing Normal University have made important progress in the research of conductive metal organic framework materials They developed a new two-dimensional complex material with redox activity and high proton conductivity, and found a new conductive motor based on "in-plane proton conduction / interface pseudocapacitance coupling" in the material The related work was published online on matter (DOI: 10.1016 / j.mat 2019.12.018) with a paper entitled "high electrical conductivity in a 2D MOF with intrinsic superprotonic production and interactive pseudocapital" Matter is the flagship journal of cell press materials Su Jian, postdoctoral student, he Wen and Li Xiaomin, Ph.D student of Nanjing Normal University are the co first authors of this paper, and Professor Zuo Jinglin, Professor Ding mengning and Professor LAN Yaqian are the corresponding authors Dr Sun Lei from Northwestern University also participated in the research Porous metal organic framework materials with both electronic conductivity and ionic conductivity may bring new opportunities and development for the design of new fuel cells, green energy technology and semiconductor related fields The above research team worked closely together to prepare a two-dimensional metal organic framework material in ttfoc (1.30 × 10 − 2 s cm − 1, 303 K, 98% RH) with high proton conductivity by using tetrathiafulvalene benzooctacarboxylic acid ligand (h8ttfoc) based on topology guided synthesis and spatial placement of carboxyl groups (Fig 1) By means of single crystal X-ray diffraction and variable temperature proton conductivity study, it is proved that the higher proton conductivity in in ttfoc comes from the synergistic action among a large number of water molecules, dimethylammonium cations and uncoordinated carboxyl groups in the pore channel, and the proton conductivity mechanism is grothuss mechanism Fig 1 crystal structure diagram of in-m-ttftb and in ttfoc, two-dimensional metal organic framework materials (source: matter) When they further studied the electronic conductivity behavior of in ttfoc, they found that the proton conductivity of the material can be completely converted into the electronic conductivity of the total circuit In general, the contact interface between the ionic conductive material (such as PEDOT) and the metal electrode will limit the further conduction of protons Therefore, the pure ionic conductivity needs to achieve further interface charge transfer through a special mechanism, and finally converted into the total circuit conductive behavior Based on solid-state electrochemical studies and the potential correlation of nonlinear I-V curves, the team pointed out that TTF ligands with redox activity in in ttfoc structure play an important role in the process of interface charge transfer, namely TTF with electrochemical activity The Faraday current (i.e., ligand induced pseudocapacitance) can be provided by the self redox of the building element at the interface between the gold electrode and the sample (Fig 2) Based on this, they propose a novel "ion conduction / pseudocapacitance coupling" mechanism in this paper, which explains the charge transfer process at the interface between the two-dimensional metal organic framework material and the metal electrode This mechanism provides theoretical guidance for the subsequent design of conductive complex porous materials and devices This kind of two-dimensional complex materials with both effective proton and electron conduction can be used in new functional electronic devices, neural morphology and energy conversion or memory devices Fig 2 the results of conducting test of in ttfoc and the schematic diagram of "ion conducting / pseudocapacitance coupling" electronic conducting mechanism (source: matter) the above research work has been supported or supported by the National Key Laboratory of coordination chemistry, the collaborative innovation center of Artificial Microstructure science and technology, the Key Laboratory of mesoscopic chemistry Ministry of education, the national major scientific research program of quantum control of the Ministry of science and technology, the National Natural Science Foundation, Jiangsu Natural Science Foundation and other projects.