Zhao Dongyuan, academician of Fudan University, JACS: accurately control the pore size and structure of mesoporous carbon spheres with nano microemulsion assembly method.

Mesoporous carbon material is a new kind of mesoporous material In addition to its high specific surface area and pore volume, it also has unique properties, such as adjustable surface properties, high chemical stability, good thermal conductivity and mechanical stability Therefore, it has a very broad application prospect in adsorption, separation, energy storage and electrochemistry Although mesoporous carbon nanospheres have such excellent properties and application prospects, it is very difficult to precisely control the pore size and structure Especially, the synthesis of macroporous (> 20 nm) mesoporous carbon spheres is a great challenge Many ways have been developed to achieve this goal The representative method is the soft template method (such as ps-b-ps) with high molecular weight surfactant as template The synthesis of macroporous carbon spheres is realized by adjusting the length of hydrophobic segment (PS segment) of surfactant This method can achieve continuous pore control, but the synthesis process of surfactant is complex and pore control is limited Another representative method is the hard template method with SiO2 nanospheres as the template, through adjusting the size of SiO2 spheres and selecting appropriate precursors to achieve the pore adjustment of mesoporous carbon spheres This method can get macroporous carbon spheres, but the synthesis process is also very complex and time-consuming, and the strong corrosive solution used in the later process of removing the hard template is dangerous, which is not suitable for large-scale synthesis Other synthesis methods, such as bubble assisted method, phase separation method and multi surfactant method, have disadvantages in particle size, morphology control, pore uniformity and so on So far, the synthesis of mesoporous carbon nanospheres has not been realized by precisely adjusting the pore size and structure of mesoporous carbon nanospheres, so it is necessary to explore the universal method to prepare mesoporous carbon nanospheres (source: J Am Chem Soc.) recently, a team of academician Zhao Dongyuan of Fudan University published a report on JACS, reporting a universal method of nano microemulsion assembly developed by the research group to synthesize mesoporous carbon nanospheres with adjustable aperture and structure (J Am Chem Soc 2019, 141, 7073-7080) Using commercial Pluronic F127 as template, dopamine (DA) as carbon source and nitrogen source, and 1,3,5-trimethylbenzene (TMB) as regulator, a series of nitrogen doped carbon nanospheres with adjustable pore size were synthesized in the system of water and ethanol In the process of synthesis, the author found that the organic small molecule (TMB) not only plays an important role in the pore size, but also has a great influence on the interface formed by the soft template (F127) and the precursor (DA) Therefore, by adjusting the amount of TMB, the assembly mode of micelles can be effectively controlled, so as to achieve the purpose of controlling the pore and structure of carbon spheres Smooth carbon spheres, golf shaped carbon spheres, multi cavity carbon spheres and dendritic carbon spheres are obtained respectively The pores of the synthesized carbon spheres can be continuously controlled in the range of 5-37 nm Among them, dendritic carbon spheres have large pore size (~ 37 nm), small particle size (~ 128 nm), high specific surface area (~ 635 M 2 g-1) and rich nitrogen content (~ 6.8 wt%) Thanks to these unique physical and chemical properties, it shows excellent oxygen reduction performance (ORR) in alkaline electrolyte, including high current density, excellent cycle stability and methanol resistance This simple and ingenious nanoemulsion synthesis strategy provides a new idea for the synthesis of novel nanostructures The corresponding authors of this paper are Zhao Dongyuan, academician of Fudan University, and Li Wei, a young researcher This work has been greatly supported by the Department of chemistry, Fudan University, the State Key Laboratory of polymer molecular engineering, Shanghai Key Laboratory of molecular catalysis and functional materials, the state key R & D project, the National Natural Science Foundation of China, Shanghai Science and Technology Commission, and Shanghai Qixing project.