Hydrogen production from formic acid decomposition(FAD)is a promising means of hydrogen energy storage and utilization in fuel cells.Development of efficient catalysts for dehydrogenation of formic acid is a challengi...Hydrogen production from formic acid decomposition(FAD)is a promising means of hydrogen energy storage and utilization in fuel cells.Development of efficient catalysts for dehydrogenation of formic acid is a challenging topic.The surface chemical and electronic structure of the active catalysis components is important in formic acid decomposition at room-temperature.Here,the pyrdinic-nitrogen doped catalysts from hyperbranched polyamide were prepared via in situ polymerization reaction process by using activated carbon as a support.Because of the introduction of the polymer,the particles of the catalysts were stabilized,and the average particle diameter was only 1.64 nm.Under mild conditions,the catalysts activities were evaluated for FAD.The optimized Pd-N30/C catalyst exhibited high performance achieving almost full conversion,with a turnover frequency of 3481 h^-1 at 30℃.展开更多
Binders are of vital importance in stabilizing the cathodes to enhance the cycling stability of lithiumsulfur(Li-S) batteries. However, conventional binders are typically confronted with the drawback of inability for ...Binders are of vital importance in stabilizing the cathodes to enhance the cycling stability of lithiumsulfur(Li-S) batteries. However, conventional binders are typically confronted with the drawback of inability for adsorbing lithium polysulfide(Li PS), thus resulting in severe active material losing and rapid capacity fading. Herein, a novel water-soluble hyperbranched poly(amidoamine)(HPAA) binder with controllable hyperbranched molecular structure and abundant amino end groups for Li-S battery is designed and fabricated, which can improve efficient adsorption for Li PS and stability of the sulfur cathodes. Besides, the strong intermolecular hydrogen bonds in HPAA binder can contribute to the structural stability of S cathode and integration of the conductive paths. Therefore, the Li-S battery with this functional binder exhibits excellent cycle performance with a capacity retention of 91% after 200 cycles at 0.1 C.Even at a high sulfur loading of 5.3 mg cm-2, a specific capacity of 601 mA h g-1 can also be achieved.Density functional theory(DFT) calculation further demonstrates that the enhanced electrochemical stability derives from the high binding energy between amino groups and LiP S and the wide electrochemical window(6.87 e V) of HPAA molecule. Based on the above all, this functional polymer will lighten a new species of binders for eco-friendly sulfur cathodes and significantly promote the practical applications of high-performance Li-S batteries.展开更多
Nano-SiO2 was modified using silane coupling agent （KH-550） and hyperbranched poly（amine-ester） respectively, and Poly（vinyl chloride） （PVC）/modified nano-SiO2 composites were made by melt-blending. The compos...Nano-SiO2 was modified using silane coupling agent （KH-550） and hyperbranched poly（amine-ester） respectively, and Poly（vinyl chloride） （PVC）/modified nano-SiO2 composites were made by melt-blending. The composites＇ structures andmechanical properties were characterized by transmission electron microscopy（TEM）, sanning electronic microscopy（SEM） and electronic universal testing machine. The results. show that nano-SiO2 grafted by hyperbranched poly （amine-ester） increases obviously in dispersion in PVC matrix, and mechanical properties of PVC are effectively improved. Moreover, it was found that mechanical properties of PVC/nano-SiO2 composites reach the best when weight percent of nano-SiO2 in PVC matrix is 1%. Compared with crude PVC, the tensile strength of hyperbranched poly （amine-ester） grafted nano-SiO2/ PVC composite increases by 24.68 % and its break elongation, flexural strength and impact strength increase by 15.73%, 4.07% and 1 841.84%, respectively. Moreover, the processing of the composites is improved.展开更多
The two-photon fluorescence properties and ultrafast responses of a hyperbranched polyyne （hb-DPP-J2） with triphenylamine as the central core, Diketo-Pyrrolo-Pyrrole as the connecting unit and electron acceptor are ...The two-photon fluorescence properties and ultrafast responses of a hyperbranched polyyne （hb-DPP-J2） with triphenylamine as the central core, Diketo-Pyrrolo-Pyrrole as the connecting unit and electron acceptor are studied. The polymer has a D-π-A-π-D conjugated structure along the extended polyyne w-bridge systems, and the effective condugated unit repeats itself in the whole hyperbranehed polymer chain. The polymer exhibits a large two-photon absorption cross section and high fluorescence quantum yields. The ultrafast dynamic results give a deep understanding of the excited energy transfer processes under excitation, and reveal a long relaxation lifetime of the intramolecular charge transfer （ICT） state.展开更多
A new method of surface chemical modification of nano-SiO2 is proposed in this paper. In the presence of catalyst, the active hydroxyl groups on the surface of nano-SiO2 reacted with AB2-type monomer （N, N-dihydroxye...A new method of surface chemical modification of nano-SiO2 is proposed in this paper. In the presence of catalyst, the active hydroxyl groups on the surface of nano-SiO2 reacted with AB2-type monomer （N, N-dihydroxyethyl-3-amino methyl propionate） by one-step polycondensation. And the product＇s Fourer transform infrared （FTIR） graphs and transmission electron microscopy（TEM） images proved that hyperbranched poly （amine-ester） was grafted on nano-SiO2 surface successfully. Results show that the modified nano-SiO2 exhibits excellent dispersion and stability in some solvents such as alcohol and chloroform.展开更多
Oil and water separation has always been a top priority in the oil industry.In this study,a series of hyperbranched fluorinated polyamine-amine polymers(HFPA1-5)were synthesized directly using an improved“one-pot met...Oil and water separation has always been a top priority in the oil industry.In this study,a series of hyperbranched fluorinated polyamine-amine polymers(HFPA1-5)were synthesized directly using an improved“one-pot method.”The highly active fluorinated p-trifluoromethylaniline was used as the core raw material,while diethylenetriamine and methyl acrylate were used as the chain segment.A hyperbranched fluorine-containing polyamine-amine demulsifier(NHFPA6)was obtained through nano-grafting copolymerization of HFPA5.To enhance the demulsification and dehydration performance,the copolymerized HFPA6 was modified and combined.Then,the effects of the combination ratio,demulsifier concentration,demulsification time,and demulsification temperature on the demulsification effect were investigated.The results revealed that a combination ratio of DE-401:NHFPA6=1:1,a demulsification temperature of 50℃,a demulsification time of 60 min,and a demulsifier concentration of 150 mg/L yielded a dehydration rate as high as 99.80%.A response surface optimization design of demulsification conditions was performed.The model verified that the optimal demulsification conditions were 50℃,300 mg/L,and 90 min.However,considering the economic benefits of factories,it is more favorable to select demulsification conditions with a shorter time and lower concentration when the dehydration standard is met.Therefore,the demulsification conditions were selected as 50℃,150 mg/L,and 60 min.Compared to existing demulsifiers,the demulsifier developed in this study exhibits a lower demulsification temperature and higher demulsification efficiency.展开更多
基金supported by the National Natural Science Foundation of China (21633008, 21733004, and 21603216)Jilin Province Science and Technology Development Program (20180101030JC)+2 种基金the Hundred Talents Program of Chinese Academy of Sciencesthe Recruitment Program of Foreign Experts (WQ20122200077)RFBR (18-53-53025)
文摘Hydrogen production from formic acid decomposition(FAD)is a promising means of hydrogen energy storage and utilization in fuel cells.Development of efficient catalysts for dehydrogenation of formic acid is a challenging topic.The surface chemical and electronic structure of the active catalysis components is important in formic acid decomposition at room-temperature.Here,the pyrdinic-nitrogen doped catalysts from hyperbranched polyamide were prepared via in situ polymerization reaction process by using activated carbon as a support.Because of the introduction of the polymer,the particles of the catalysts were stabilized,and the average particle diameter was only 1.64 nm.Under mild conditions,the catalysts activities were evaluated for FAD.The optimized Pd-N30/C catalyst exhibited high performance achieving almost full conversion,with a turnover frequency of 3481 h^-1 at 30℃.
基金the Startup Research Fund of Dongguan University of Technology(KCYKYQD2017015)Leading Talents of Innovation and Entrepreneurship of the Dongguan City D2017(16)the Australian Research Council(ARC)through the ARC Discovery project(DP160104340)。
文摘Binders are of vital importance in stabilizing the cathodes to enhance the cycling stability of lithiumsulfur(Li-S) batteries. However, conventional binders are typically confronted with the drawback of inability for adsorbing lithium polysulfide(Li PS), thus resulting in severe active material losing and rapid capacity fading. Herein, a novel water-soluble hyperbranched poly(amidoamine)(HPAA) binder with controllable hyperbranched molecular structure and abundant amino end groups for Li-S battery is designed and fabricated, which can improve efficient adsorption for Li PS and stability of the sulfur cathodes. Besides, the strong intermolecular hydrogen bonds in HPAA binder can contribute to the structural stability of S cathode and integration of the conductive paths. Therefore, the Li-S battery with this functional binder exhibits excellent cycle performance with a capacity retention of 91% after 200 cycles at 0.1 C.Even at a high sulfur loading of 5.3 mg cm-2, a specific capacity of 601 mA h g-1 can also be achieved.Density functional theory(DFT) calculation further demonstrates that the enhanced electrochemical stability derives from the high binding energy between amino groups and LiP S and the wide electrochemical window(6.87 e V) of HPAA molecule. Based on the above all, this functional polymer will lighten a new species of binders for eco-friendly sulfur cathodes and significantly promote the practical applications of high-performance Li-S batteries.
基金Sponsored by the Ministerial Level Advanced Research Foundation (120701BQ0126)
文摘Nano-SiO2 was modified using silane coupling agent （KH-550） and hyperbranched poly（amine-ester） respectively, and Poly（vinyl chloride） （PVC）/modified nano-SiO2 composites were made by melt-blending. The composites＇ structures andmechanical properties were characterized by transmission electron microscopy（TEM）, sanning electronic microscopy（SEM） and electronic universal testing machine. The results. show that nano-SiO2 grafted by hyperbranched poly （amine-ester） increases obviously in dispersion in PVC matrix, and mechanical properties of PVC are effectively improved. Moreover, it was found that mechanical properties of PVC/nano-SiO2 composites reach the best when weight percent of nano-SiO2 in PVC matrix is 1%. Compared with crude PVC, the tensile strength of hyperbranched poly （amine-ester） grafted nano-SiO2/ PVC composite increases by 24.68 % and its break elongation, flexural strength and impact strength increase by 15.73%, 4.07% and 1 841.84%, respectively. Moreover, the processing of the composites is improved.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11404048,61205154 and 11375034the Fundamental Research Funds for the Central Universities under Grant Nos 3132015233,3132013104,3132014337,3132015144 and3132015152+1 种基金the State Key Laboratory of Fine Chemicals(KF1409)the Program for Liaoning Excellent Talents in University under Grant No LJQ2014051
文摘The two-photon fluorescence properties and ultrafast responses of a hyperbranched polyyne （hb-DPP-J2） with triphenylamine as the central core, Diketo-Pyrrolo-Pyrrole as the connecting unit and electron acceptor are studied. The polymer has a D-π-A-π-D conjugated structure along the extended polyyne w-bridge systems, and the effective condugated unit repeats itself in the whole hyperbranehed polymer chain. The polymer exhibits a large two-photon absorption cross section and high fluorescence quantum yields. The ultrafast dynamic results give a deep understanding of the excited energy transfer processes under excitation, and reveal a long relaxation lifetime of the intramolecular charge transfer （ICT） state.
基金Sponsored by the Ministerial Level Advanced Research Foundation (120701BQ0126)
文摘A new method of surface chemical modification of nano-SiO2 is proposed in this paper. In the presence of catalyst, the active hydroxyl groups on the surface of nano-SiO2 reacted with AB2-type monomer （N, N-dihydroxyethyl-3-amino methyl propionate） by one-step polycondensation. And the product＇s Fourer transform infrared （FTIR） graphs and transmission electron microscopy（TEM） images proved that hyperbranched poly （amine-ester） was grafted on nano-SiO2 surface successfully. Results show that the modified nano-SiO2 exhibits excellent dispersion and stability in some solvents such as alcohol and chloroform.
基金supported by National Natural Science Foundation of China(NSFC 21676145)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD,China).
文摘Oil and water separation has always been a top priority in the oil industry.In this study,a series of hyperbranched fluorinated polyamine-amine polymers(HFPA1-5)were synthesized directly using an improved“one-pot method.”The highly active fluorinated p-trifluoromethylaniline was used as the core raw material,while diethylenetriamine and methyl acrylate were used as the chain segment.A hyperbranched fluorine-containing polyamine-amine demulsifier(NHFPA6)was obtained through nano-grafting copolymerization of HFPA5.To enhance the demulsification and dehydration performance,the copolymerized HFPA6 was modified and combined.Then,the effects of the combination ratio,demulsifier concentration,demulsification time,and demulsification temperature on the demulsification effect were investigated.The results revealed that a combination ratio of DE-401:NHFPA6=1:1,a demulsification temperature of 50℃,a demulsification time of 60 min,and a demulsifier concentration of 150 mg/L yielded a dehydration rate as high as 99.80%.A response surface optimization design of demulsification conditions was performed.The model verified that the optimal demulsification conditions were 50℃,300 mg/L,and 90 min.However,considering the economic benefits of factories,it is more favorable to select demulsification conditions with a shorter time and lower concentration when the dehydration standard is met.Therefore,the demulsification conditions were selected as 50℃,150 mg/L,and 60 min.Compared to existing demulsifiers,the demulsifier developed in this study exhibits a lower demulsification temperature and higher demulsification efficiency.
