Research group of Professor Qiao Zhen'an of Jilin University: design, synthesis and application of new polymer colloidal spheres and carbon spheres

The introduction of micro / nano colloidal spheres has attracted extensive attention in the scientific research field due to its controllable size, chemical composition, internal structure and crystallinity In recent decades, scientists have successfully synthesized a series of representative colloidal spheres, such as silica colloidal sphere, polystyrene colloidal sphere, phenolic resin colloidal sphere, etc the appearance of each colloidal sphere has promoted the development of nanoscience These colloidal spheres show excellent and unique properties in the fields of biomedicine, colloidal catalyst, active material packaging and photonic crystal, especially the polymer colloidal spheres with high stability, such as phenolic resin, can be transformed into porous carbon colloidal spheres through high-temperature treatment, which are widely used in energy conversion and storage, gas adsorption and separation, electrocatalysis and other hot fields However, the synthesis strategies of these polymer colloidal spheres still have some limitations: (1) the chemical reactions applicable to the synthesis of colloidal spheres are limited, and the current synthesis mostly focuses on the improvement of traditional colloidal spheres, lacking the exploration of new reactions; (2) ）The synthesis conditions of polymer colloidal spheres are relatively strict, and only colloidal spheres with narrow average size range can be synthesized by specific synthesis strategies, and a large number of organic solvents used in polymerization are harmful to the environment; (3) most of the synthesized polymer colloidal spheres have poor thermal stability, and the research on the composite structure of polymer colloidal spheres is relatively small; (4 ）It is still a difficult problem to control the pore and structure of polymer colloidal spheres These limitations limit the synthesis and application of colloidal spheres to a great extent, so it is necessary to explore new synthesis strategies under mild conditions to produce functional colloidal spheres Recently, Professor Qiao Zhen'an's research group of Jilin University has made a new breakthrough in this field Relevant research results were published in adv mater (DOI: 10.1002 / ADMA 201807876) Introduction to the research group of Professor Qiao Zhen'an in autumn 2015, Dr Qiao Zhen'an returned to the school of chemistry of Jilin University as a full-time Professor, established the State Key Laboratory of inorganic synthesis and preparation chemistry and led the research group independently Dr Qiao Zhen'an has been engaged in the design, synthesis and Performance Research of new functional mesoporous materials for a long time Based on the key scientific issues of porous materials synthesis methodology, a series of new multifunctional porous materials were designed and accurately synthesized, and their applications in catalysis, adsorption, energy storage and transformation were developed, and a series of pioneering scientific research results were obtained Typical examples include new porous catalysts (adv mater 2019, 1806254; J am Chem SOC 2014, 136, 11260; chem Mater 2017, 29, 4044; chem Mater 2018, 30, 8579), porous materials for energy conversion and storage (adv mater 2019, 1807876; NPG Asia mater 2018, 10, 800; nano lett 2013, 13, 207), porous materials for adsorption (NAT Commun 2014, 5, 3705; angel Chem Int ed 2012, 51, 2888; adv mater 2012, 24, 6017) Prof Qiao Zhen'an, Professor, doctoral supervisor, was selected into the Sixth Batch of "youth thousand talents plan" of the central organization department In 2011, he received his doctorate from Jilin University From 2011 to 2015, he worked as a postdoctoral researcher at the University of Tennessee and Oak Ridge National Laboratory In 2015, he returned to Jilin University full-time to work in the State Key Laboratory of inorganic synthesis and preparation chemistry The main research direction is the design, synthesis and properties of new functional mesoporous materials He has published more than 60 SCI retrieval papers in famous international magazines such as NAT Commun., J am Chem SOC., angelw Chem Int ed., adv mater., nano lett., etc., and has cited more than 2000 times in total His H factor is 24 He participated in writing one English treatise and obtained one American patent Presided over one general project of NSFC, one innovation research group project of NSFC as the backbone, and one project of "111" intelligence introduction plan of Ministry of education as the backbone Cutting edge scientific research achievements: Based on the self polymerization of 2,6-diaminopyridine (DAP), the author has successfully designed and synthesized a new type of nitrogen rich polymer colloidal sphere poly (2,6-diaminopyridine (PDAP) nanospheres (chem Mater 2017, 29, 4044) The average size of the nanospheres can be adjusted by the content of ethanol in the solvent and the concentration of ammonium persulfate, and the particle size can be adjusted from 76-331 nm The hydrophilicity of polymer colloidal spheres can be changed from super hydrophilic to amphiphilic by changing different surfactants The synthesis conditions of the polymer nanospheres are mild, and the polymerization can be completed within 5 minutes at room temperature The product can be synthesized more than 10 g at a time, and the microporous carbon with nitrogen content up to 24 wt% can be easily obtained through high-temperature pyrolysis, showing the alkalinity which is very conducive to carbon dioxide adsorption In this way, the synthesized PDAP has good expansibility It can not only cover typical nanoparticles to form core-shell composite nanospheres, but also use rich nitrogen sites to stabilize precious metal nanoparticles in the process of pyrolysis The composite Pd / pdap-500 loaded with ultra-small palladium nanoparticles has been studied in this paper It shows excellent activity and high selectivity in the solvent-free oxidation of alcohols Fig 1 synthesis and application of PDAP colloidal spheres (source: chem Mater.) based on the above research work, the author proposed a surfactant induced limited area polymerization strategy to synthesize nitrogen doped multi chamber carbon microsphere (MCC) with fine structure The precursor of the carbon sphere is a novel multicavity polymer (MCP) based on 2,6-diaminopyridine (DAP) One pot synthesis of MCP involves two polymerization steps In the first step, DAP and formaldehyde grow into a prepolymer dap-f with cytoskeleton like structure in alkaline solution In the process of polymerization, polymer surfactant F127 and anionic surfactant sodium dodecylbenzene sulfonate form a double surfactant system to control the growth of dap-f prepolymer Among them, F127 is used as a space stabilizer to prevent the agglomeration of dap-f particles The amino groups in DAP molecules can reduce the electrostatic repulsion of anionic surfactants, which leads to the formation of large cavities in dap-f After adding acetic acid, the second stage of polymerization began With the decrease of pH value of the solution, the prepolymer of dap-f was further crosslinked The polymerization of dap-f in the confined space of microspheres resulted in the separation of large cavities and the formation of abundant small cavities F I g 2 a) schematic diagram of MCC synthesis process; B, H) MCP; C, I) mcp-f; D, e, J) MCP; F, G, K) SEM of MCC (source: adv mater.) in order to better understand the process of spatial separation, the author obtained the intermediate product mcp-f by reducing the amount of acetic acid added By comparing the electron micrographs, it can be found that the chamber size and number of mcp-f are between the precursor dap-f and the final product MCP, which indicates that the space inside the polymer microspheres is gradually subdivided with the polymerization in the second step Fig 3 A) MCP TEM; b) MCC TEM; c) optical photo of 12 g MCP powder; d) MCC HRTEM; E) nitrogen adsorption isotherm of MCC XH at 77 K; F) DFT hole distribution of MCC XH; g) C XPS of MCP and mcc-2h; n XPS of MCP and mcc-2h (source: adv mater.) MCP can be activated in nitrogen / carbon dioxide environment to obtain multi chamber carbon MCC With the prolongation of activation time, the micropores in MCC increased rapidly After 4 hours of activation, the mesopores near 20 nm increased significantly in the pore distribution The pore size of mesopores was consistent with the chamber size in TEM, and the activation time continued to be prolonged, but the distribution of mesopores did not change significantly This shows that with the prolongation of activation time, the cavities in MCC can be connected by abundant micropores, and the BET specific surface area of mcc-6h is up to 1797m2 / g Fig 4 a) the influence of different synthesis conditions on dap-f morphology; b) the influence of different proportion of SDBS / F127 on the size and internal structure of MCP (source: adv mater.) the author verified the regulation mechanism of double surfactant by control variable method: when F127 is the only surfactant, the product is nanospheres; SDBS When it is the only surfactant, the product is a multi chamber block material; when there is no surfactant, the product is a solid block material These results confirm the hypothesis that F127 can inhibit the agglomeration of particles and SDBS can induce the formation of multicavity Moreover, by changing the ratio of SDBS / F127, the size of MCP can be easily adjusted between 250 and 3091nm Fig 5 performance test of MCP XH super capacitor: a) CV Curve; b) constant current charge and discharge; c) specific capacity under different current density; d) cycle stability (source: adv mater.) through performance test of super capacitor, the author finds that mcc-6h has the best performance, which benefits from the fully penetrated multi chamber classification structure The specific capacitance of mcc-6h can reach 301 f / g at the current of 0.2 A / g, which is a potential super capacitor material The significance of this study is that a new type of N-doped multicavity polymer and carbon microspheres have been synthesized by the surfactant induced confinement polymerization strategy Double surfactants can not only be used to control the formation of multi cavity structure in polymer, but also can easily adjust the ratio to achieve the large-scale control of product size from 250-3091 nm The carbon micro sphere with multi cavity core and microporous shell reported in this paper can be used as a new super capacitor material to achieve high specific capacitance, excellent high power performance and long cycle stability This achievement was recently published in adv mater The authors of this paper are: Tao Wang, Yan sun, Liang Zhang, Kaiqian Li, Yikun Yi, Shuyan song, Mingtao Li, Zhen An Qiao *, Sheng Dai (adv mater 2019, DOI: 10.1002 / ADMA 201807876) 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.