Donghua University has made important progress in the field of pore and electronic structure control of carbon nanofibers

Recently, academician Yu Jianyong and research team Ding bin of Donghua University have made important progress in the research field of pore and electronic structure regulation of flexible carbon nanofibers Relevant achievements were published in nature communications (DOI: 10.1038 / s41467-019-13430-9) on the topic of "multifunctional flexible members from spine like groups carbon nanofibers with high conductivity" ）, the first author of this paper is researcher Yan Jianhua, and the corresponding author is researcher Ding bin Porous carbon nanofibers are rich in pores and electronic structures They not only have the small size effect of inorganic nanomaterials, excellent heat resistance and chemical stability, but also are easy to form self-supporting films, avoiding the defects of increased interface resistance and reduced mass transfer efficiency caused by the use of binders Therefore, they play a huge role in energy, sensing, environment and other fields At present, the main methods to prepare porous carbon nanofibers are activation method and template method The activation method mainly uses KOH or HNO 3 and other corrosive chemicals to etch carbon nanofibers for pore formation The template method mainly uses the mixture of calcined asphalt or polyacrylonitrile and pore forming agent to form porous carbon fibers in situ However, the activation method is usually complex and has pollution and safety problems, while the template method needs to consume a lot of organic solvents In addition, the porosity and conductivity of carbon nanofibers prepared by these two methods are low On the one hand, in order to ensure the integrity of carbon nanofiber membrane structure, the porosity of most reported porous carbon nanofibers is less than 20%; on the other hand, the conductivity of these porous carbon nanofibers is usually less than 10 s / cm Therefore, it is a challenge to improve the porosity and conductivity of porous carbon nanofiber membrane while maintaining its integrity Based on this problem, the research team developed a method based on water electrospinning and macro micro biphase separation technology to prepare flexible porous carbon nanofiber membranes with high porosity and high conductivity In this study, the uniform mixing of carbon precursor and pore forming agent is the key factor to control porosity and conductivity Here, polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE) particles and boric acid (BA) are used as carbon precursor, macroporous inducer, crosslinker and microporous inducer respectively Among them, Ba formed stable pva-ba-ptfe spinning sol through chemical crosslinking with PVA and PTFE, avoiding self entanglement of PVA macromolecules; during preoxidation at 280 ℃, PVA dehydrogenation formed conjugated C = C bond, improving the stability of primary fiber; after high-temperature pyrolysis in nitrogen, it formed B-f-n ternary doped flexible, high conductivity, porous carbon nanofibers The continuous carbon skeleton in the whole porous carbon nanofibers provides a fast channel for electron conduction, while the three-stage pore structure (macropore mesopore micropore, porosity higher than 80%) reduces the transport resistance of ions, molecules, particles and other substances, so it shows versatility in the fields of gas adsorption, sewage treatment, liquid storage, super capacitors and batteries For example, the fiber membrane has high liquid storage capacity and fast methylene blue dye adsorption capacity; the all carbon symmetrical super capacitor prepared with the fiber membrane has high power density and energy density; when used as a sulfur electrode, the capacity of the lithium sulfur battery can reach 1200 MAH / G under the charge and discharge of 1 c current The research results have been greatly supported by NSFC, national key research and development plan, double hundred technology research project of national defense science and Engineering Bureau, major natural science project of Shanghai Municipal Education Commission, Shanghai overseas high-level talent project, youth support project of China Association for science and technology.