Wang Yaobing research group of Fujian Institute of physical composition, Chinese Academy of Sciences: functional covalent organic skeleton materials for direct storage of solar energy to electrochemical energy

Lead to store solar energy in electrochemical energy storage devices is an effective way to solve the intermittent supply of solar energy and realize its wide application The traditional method is to connect the solar cell with the energy storage device through a long wire The introduction of a long wire will lead to ohmic loss, thus reducing the conversion and storage efficiency of solar energy The design and preparation of high-efficiency (optoelectronic) functional electrode materials, the development and construction of simple two electrode system devices are the key to obtain high-efficiency and low-cost optical assisted electrochemical energy storage equipment Covalent organic framework materials (COFS) are a new kind of porous polymers, which can assemble the required structural units precisely into a solid network structure with open channels, so it provides a new strategy to combine redox active sites and organic semiconductor molecules in a rigid network with high designability Recently, Wang Yaobing's research group of Fujian Institute of material structure, Chinese Academy of Sciences and its collaborator yuan Daqiang's research group have made a breakthrough in this field (angel Chem Int ed., DOI: 10.1002/anie.201806596) Wang Yaobing, Ph.D., graduated from the school of chemistry and materials science, Hubei University in 2003, received his Ph.D in physical chemistry from the Institute of chemistry, Chinese Academy of Sciences in 2008 (Tutor: academician Yao Jiannian), and then engaged in postdoctoral research in the Department of chemistry, University of California, riverside, United States (co Tutor: Chris Bardeen ) In 2009, he returned to Shenzhen to work on graphene industrialization project In December 2012, he was introduced to Fujian Institute of material structure of Chinese Academy of Sciences with high-level talents and served as a researcher and project leader He has published more than 30 articles in adv mater., angelw Chem Int ed., adv func Mater., nano energy, j.mater Chem A and other internationally famous journals, and obtained more than 40 authorized patents Cutting edge research results: functional covalent organic skeleton materials are used for direct storage of solar energy to electrochemical energy recently, Wang Yaobing of Fujian Institute of material structure, Chinese Academy of Sciences The research group and Yuan Daqiang research group reported a new method to directly convert solar energy into electrochemical energy by using dual functional materials with both light absorption and reversible electrochemical energy storage First of all, Dr Tan Yanxi of Yuan Daqiang's research group has synthesized a covalent organic framework material (nt-cof) with naphthalene diimide (NDI) and triphenylamine (TPA) units The specific surface area of the two-dimensional porous nt-co nano sheet is up to 1276 M 2 / g Dr Lu Jiangquan of Wang Yaobing's research group carried out detailed photochemical / electrochemical characterization, revealed the efficient intramolecular charge transfer from TPA to NDI unit in nt-cof and the highly reversible electrochemical reaction of the material Nt-cof is the cathode material of lithium-ion battery Under the illumination, the charging voltage is reduced by 0.5 V, the discharge voltage is increased by 0.5 V, and the efficiency of the whole battery is increased by 38.7%, which realizes the effective utilization of solar energy Based on the bifunctional cathode materials with reversible electrochemical properties and intramolecular charge transfer synergy, a new solar electrochemical energy conversion / storage system is designed, which provides a new idea for replacing integrated solar cells and battery systems The nt-cof material was successfully obtained by a simple dehydration condensation reaction According to X-ray powder diffraction analysis and structural simulation, the material has good crystallinity and belongs to the hexagonal space group (p-31m) The specific surface area of the material is as high as 1276 M 2 / g, and the pore size distribution is concentrated at 1.2-3.0 nm (Fig 1) This kind of rigid structure is conducive to the stability of the material in the subsequent electrochemical reaction At the same time, high specific surface area and rich pore structure are also conducive to the mass transfer process in the electrochemical reaction Fig 1 Synthesis, structure and characterization of nt-cof (source: angel Chem Int ed.) the naphthalene diimide (NDI) and triphenylamine (TPA) in nt-cof are often used in organic optoelectronic devices as electron deficient and electron rich units In order to explore the optical properties of nt-cof, the author has carried out a detailed characterization By comparing the UV absorption, fluorescence absorption and emission spectra of nt-cof and the two monomers, it is inferred that there is an intramolecular charge transfer process in nt-cof The results of femtosecond transient absorption spectroscopy (FS TA) further prove that there is an effective intramolecular charge transfer from TPA unit to NDI unit in nt-cof, and the charge transfer efficiency is very high Figure 2 The optical properties of nt-cof (source: angel Chem Int ed.) cyclic voltammetry test results show that the redox reaction of nt-cof is reversible C = O in nt-cof can be used as the site of reversible lithium removal and intercalation Under the illumination, the redox peak of nt-cof shifted, which proved that the photoelectric conversion process can be effectively coupled with the electrochemical process Figure 3 Electrochemical characterization of nt-cof (source: angelw Chem Int ed.) because nt-cof has both photoelectric response and reversible lithium removal and intercalation functions, the author uses nt-cof as cathode material of lithium-ion battery, and explores the change of battery performance under light It can be seen from Fig 4 that when the constant current is charged and discharged, the light reduces the charging voltage by about 0.5 V, and the discharge voltage increases by about 0.5 V, and the device remains stable under multiple light dark alternating cycles Figure 4 Response of lithium-ion battery with nt-cof as cathode material under light (source: angel Chem Int ed.) a series of results show that the COF material designed by the author has the ability of solar energy utilization and energy storage at the same time, which is expected to provide new ideas for the design of new generation solar energy storage devices Nowadays, people and scientific research have been paid more and more attention in the economic life China has ushered in the "node of science and technology explosion" Behind the progress of science and technology is the work of countless scientists In the field of chemistry, in the context of the pursuit of innovation driven, international cooperation has been strengthened, the influence of Returned Scholars in the field of R & D has become increasingly prominent, and many excellent research groups have emerged in China For this reason, CBG information adopts the 1 + X reporting mechanism CBG information, chembeangoapp, chembeango official microblog, CBG wechat subscription number and other platforms jointly launch the column of "people and scientific research", approach the domestic representative research group, pay attention to their research, listen to their stories, record their demeanor, and explore their scientific research spirit.