The synergistic effect of conventional flame-retardant elements and graphene has received extensive attention in the development of a new class of flame retardants. Compared to covalent modification, the noncovalent s...The synergistic effect of conventional flame-retardant elements and graphene has received extensive attention in the development of a new class of flame retardants. Compared to covalent modification, the noncovalent strategy is simpler and expeditious and entirely preserves the original quality of graphene. Thus, non-covalently functionalized graphene oxide(FGO) with a phosphorus–nitrogen compound was successfully prepared via a one-pot process in this study. Polyethyleneimine and FGO were alternatively deposited on the surface of a poly(vinyl alcohol)(PVA) film via layer-by-layer assembly driven by electrostatic interaction, imparting excellent flame retardancy to the coated PVA film. The multilayer FGO-based coating formed a protective shield encapsulating the PVA matrix, effectively blocking the transfer of heat and mass during combustion. The coated PVA has a higher initial decomposition temperature of about 260 °C and a nearly 60% reduction in total heat release than neat PVA does. Our results may have a promising prospect for flame-retardant polymers.展开更多
Graphene oxide has been used widely as a starting precursor for applications that cater to the needs of tunable graphene. However, the hydrophilic characteristic limits their application, especially in a hydrophobic c...Graphene oxide has been used widely as a starting precursor for applications that cater to the needs of tunable graphene. However, the hydrophilic characteristic limits their application, especially in a hydrophobic condition. Herein, a novel non-covalent surface modification approach towards graphene oxide was conducted via a UV-induced photo-polymerization technique that involves two major routes; a UV-sensitive initiator embedded via pi-pi interactions on the graphene planar rings, and the polymerization of hydrophobic polymeric chains along the surface. The functionalized graphene oxide successfully achieved the desired hydrophobicity as it displayed the characteristic of being readily dissolved in organic solvent. Upon its addition into a polymeric solution and subjected to an electrospinning process,non-woven random nanofibers embedded with graphene oxide sheets were obtained. The prepared polymeric nanofibers were subjected to two-step thermal treatments that eventually converted the polymeric chains into a carbon-rich conductive structure. A unique morphology was observed upon the addition of the functionalized graphene oxide, whereby the sheets were embedded and intercalated within the carbon nanofibers and formed a continuous structure. This reinforcement effectively enhanced the electrochemical performance of the carbon nanofibers by recording a specific capacitance of up to 140.10 F/g at the current density of 1 A/g, which was approximately three folds more than that of pristine nanofibers.It also retained the capacitance up to 96.2% after 1000 vigorous charge/discharge cycles. This functionalization technique opens up a new pathway in tuning the solubility nature of graphene oxide towards the synthesis of a graphene oxide-reinforced polymeric structure.展开更多
Graphene/acridine （G-Acr） hybrid structures were synthesized through covalent functionalization of graphene oxide with 9-（4- aminophenyl）acridine （APA） and its derivatives. The G-Act hybrids were characterized b...Graphene/acridine （G-Acr） hybrid structures were synthesized through covalent functionalization of graphene oxide with 9-（4- aminophenyl）acridine （APA） and its derivatives. The G-Act hybrids were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectrophotometry, thermal gravimetric analysis and Raman spectroscopy. X-ray photoelectron spectroscopy confirms that the binding energies of APA and its derivatives shifted to higher values, revealing pronounced charge transfer at the interface of graphene and organic molecules.展开更多
Graphene has lots of applications, such as field-effect transistors, solar cells and transparent electrodes. In this work, we developed a new donor-acceptor graphene hybrid by covalently bonding a donor phenanthrene-9...Graphene has lots of applications, such as field-effect transistors, solar cells and transparent electrodes. In this work, we developed a new donor-acceptor graphene hybrid by covalently bonding a donor phenanthrene-9-carboxaldehyde (PCA) onto the acceptor graphene (PCA-graphene) via 1,3-dipolar cycloaddition azomethine ylides. The resulting PCA-graphene is soluble in N,N-dimethyformamide (DMF). The optoelectronic device (photoanode) fabricated by spin-coating DMF solution of the hybrids exhibits an enhanced photocurrent under visible irradiation.展开更多
Green reduction of graphene oxide(GO) functionalized with 3-aminopropyltriethoxysilane and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide was performed by using ascorbic acid and sod...Green reduction of graphene oxide(GO) functionalized with 3-aminopropyltriethoxysilane and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide was performed by using ascorbic acid and sodium bisulfite.The obtained materials were characterized by thermo-gravimetric analysis,transmission electron microscopy.X-ray diffraction,UV-Vis,Fourier transform infrared and Raman spectroscopy techniques.The results indicated a strong dependence of the materials properties such as deoxygenation degree,absorption peak shift,crystallite size and functionalization degree on the functionalization approach and reducing agent.展开更多
Nanostructured organic tetralithium salts of 2,5-dihydroxyterephthalic acid （Li4C8H2O6） supported on graphene were prepared via a facile recrystallization method. The optimized composite with 75 wt.% Li4C8H2O6 was e...Nanostructured organic tetralithium salts of 2,5-dihydroxyterephthalic acid （Li4C8H2O6） supported on graphene were prepared via a facile recrystallization method. The optimized composite with 75 wt.% Li4C8H2O6 was evaluated as an anode with redox couples of Li4C8H2O6/Li6C8H2O6 and as a cathode with redox couples of Li4C8H2O6/Li2C8H2O6 for Li-ion batteries, exhibiting a high-rate capability （10 C） and long cycling life （1,000 cycles）. Moreover, in an all-organic symmetric Li-ion battery, this dual-function electrode retained capacities of 191 and 121 mA.h·g-1 after 100 and 500 cycles, respectively. Density functional theory calculations indicated the presence of covalent bonds between Li4CsH206 and graphene, which affected both the morphology and electronic structure of the composite. The special nanostructures, high electronic conductivity of graphene, and covalent-bond interaction between Li4C8H2O6 and graphene contributed to the superior electrochemical properties. Our results indicate that the combination of organic salt molecules with graphene is useful for obtaining high-performance organic batteries.展开更多
基金supported by National Natural Science Foundation of China (No. 51473095)the Program of Innovative Research Team for Young Scientists of Sichuan Province (2016TD0010)
文摘The synergistic effect of conventional flame-retardant elements and graphene has received extensive attention in the development of a new class of flame retardants. Compared to covalent modification, the noncovalent strategy is simpler and expeditious and entirely preserves the original quality of graphene. Thus, non-covalently functionalized graphene oxide(FGO) with a phosphorus–nitrogen compound was successfully prepared via a one-pot process in this study. Polyethyleneimine and FGO were alternatively deposited on the surface of a poly(vinyl alcohol)(PVA) film via layer-by-layer assembly driven by electrostatic interaction, imparting excellent flame retardancy to the coated PVA film. The multilayer FGO-based coating formed a protective shield encapsulating the PVA matrix, effectively blocking the transfer of heat and mass during combustion. The coated PVA has a higher initial decomposition temperature of about 260 °C and a nearly 60% reduction in total heat release than neat PVA does. Our results may have a promising prospect for flame-retardant polymers.
文摘Graphene oxide has been used widely as a starting precursor for applications that cater to the needs of tunable graphene. However, the hydrophilic characteristic limits their application, especially in a hydrophobic condition. Herein, a novel non-covalent surface modification approach towards graphene oxide was conducted via a UV-induced photo-polymerization technique that involves two major routes; a UV-sensitive initiator embedded via pi-pi interactions on the graphene planar rings, and the polymerization of hydrophobic polymeric chains along the surface. The functionalized graphene oxide successfully achieved the desired hydrophobicity as it displayed the characteristic of being readily dissolved in organic solvent. Upon its addition into a polymeric solution and subjected to an electrospinning process,non-woven random nanofibers embedded with graphene oxide sheets were obtained. The prepared polymeric nanofibers were subjected to two-step thermal treatments that eventually converted the polymeric chains into a carbon-rich conductive structure. A unique morphology was observed upon the addition of the functionalized graphene oxide, whereby the sheets were embedded and intercalated within the carbon nanofibers and formed a continuous structure. This reinforcement effectively enhanced the electrochemical performance of the carbon nanofibers by recording a specific capacitance of up to 140.10 F/g at the current density of 1 A/g, which was approximately three folds more than that of pristine nanofibers.It also retained the capacitance up to 96.2% after 1000 vigorous charge/discharge cycles. This functionalization technique opens up a new pathway in tuning the solubility nature of graphene oxide towards the synthesis of a graphene oxide-reinforced polymeric structure.
基金the financial support from the National Natural Science Foundation of China(Nos.21072040,21071040, 21101051 and 21272050)the Program for New Century Excellent Talents in University of the Chinese Ministry of Education(No.NCET-11-0627)
文摘Graphene/acridine （G-Acr） hybrid structures were synthesized through covalent functionalization of graphene oxide with 9-（4- aminophenyl）acridine （APA） and its derivatives. The G-Act hybrids were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectrophotometry, thermal gravimetric analysis and Raman spectroscopy. X-ray photoelectron spectroscopy confirms that the binding energies of APA and its derivatives shifted to higher values, revealing pronounced charge transfer at the interface of graphene and organic molecules.
基金supported by the National Natural Science Foundation of China (20920102034, 20877076 & 20907056)the National Basic Research Program of China (2010CB933503 & 2007CB613306)
文摘Graphene has lots of applications, such as field-effect transistors, solar cells and transparent electrodes. In this work, we developed a new donor-acceptor graphene hybrid by covalently bonding a donor phenanthrene-9-carboxaldehyde (PCA) onto the acceptor graphene (PCA-graphene) via 1,3-dipolar cycloaddition azomethine ylides. The resulting PCA-graphene is soluble in N,N-dimethyformamide (DMF). The optoelectronic device (photoanode) fabricated by spin-coating DMF solution of the hybrids exhibits an enhanced photocurrent under visible irradiation.
基金supported financially by the Romanian Authority for Scientific Research(No.PN-Ⅱ-RU-PD-2012-3-0124)The European Commission(No.NMP3-SL-2010-246073)
文摘Green reduction of graphene oxide(GO) functionalized with 3-aminopropyltriethoxysilane and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide was performed by using ascorbic acid and sodium bisulfite.The obtained materials were characterized by thermo-gravimetric analysis,transmission electron microscopy.X-ray diffraction,UV-Vis,Fourier transform infrared and Raman spectroscopy techniques.The results indicated a strong dependence of the materials properties such as deoxygenation degree,absorption peak shift,crystallite size and functionalization degree on the functionalization approach and reducing agent.
文摘Nanostructured organic tetralithium salts of 2,5-dihydroxyterephthalic acid （Li4C8H2O6） supported on graphene were prepared via a facile recrystallization method. The optimized composite with 75 wt.% Li4C8H2O6 was evaluated as an anode with redox couples of Li4C8H2O6/Li6C8H2O6 and as a cathode with redox couples of Li4C8H2O6/Li2C8H2O6 for Li-ion batteries, exhibiting a high-rate capability （10 C） and long cycling life （1,000 cycles）. Moreover, in an all-organic symmetric Li-ion battery, this dual-function electrode retained capacities of 191 and 121 mA.h·g-1 after 100 and 500 cycles, respectively. Density functional theory calculations indicated the presence of covalent bonds between Li4CsH206 and graphene, which affected both the morphology and electronic structure of the composite. The special nanostructures, high electronic conductivity of graphene, and covalent-bond interaction between Li4C8H2O6 and graphene contributed to the superior electrochemical properties. Our results indicate that the combination of organic salt molecules with graphene is useful for obtaining high-performance organic batteries.
