以天然鳞片石墨为原料,采用改良的Hummers方法,制备了高纯度的薄层或单层氧化石墨(GO);并以抗坏血酸为还原剂,通过自组装还原的方式成功制备了具有三维多孔独巨石结构的还原氧化石墨烯(r GO)气凝胶,其形貌和结构经FT-IR,SEM,TEM,XRD和XP...以天然鳞片石墨为原料,采用改良的Hummers方法,制备了高纯度的薄层或单层氧化石墨(GO);并以抗坏血酸为还原剂,通过自组装还原的方式成功制备了具有三维多孔独巨石结构的还原氧化石墨烯(r GO)气凝胶,其形貌和结构经FT-IR,SEM,TEM,XRD和XPS表征。并对其作为锂离子电池负极材料的电化学性能进行了测试。结果表明:r GO气凝胶独特的形貌和结构提高了其比容量和循环性能,在100 m A·g-1电流密度下首周放电比容量可达1 700 m Ah·g-1,首周充电比容量达710 m Ah·g-1,经过100周循环后放电比容量仍可保持在450 m Ah·g-1,库伦效率保持在98%。展开更多
Photocatalysis is considered a promising technique for removal of pollutants from indoor air.However,the low selectivity and limited recyclability of photocatalysts in powder form currently limit their practical appli...Photocatalysis is considered a promising technique for removal of pollutants from indoor air.However,the low selectivity and limited recyclability of photocatalysts in powder form currently limit their practical application.In this work,we reported the successful preparation of a monolithic tungsten oxide(WO3)/graphene oxide(GO)aerogel photocatalyst through a cost‐effective freeze‐drying method.GO not only acts as a macroscopic support,but also increases the catalyst surface area from 46 to 57 m2/g,enhances the light absorption in the visible‐light region,and raises the separation efficiency of photogenerated electron‐hole pairs.The Obtained WO3/GO aerogel exhibited an outstanding visible‐light photocatalytic degradation rate of nitric oxide of 51%,which was 3.3 times that of pristine WO3 powder.In addition,the aerogel displayed excellent selectivity,with a generation fraction of toxic nitrogen dioxide of as low as 0.5%.This work presents a facile synthesis route to fabricate a monolithic WO3/GO aerogel photocatalyst with great promise for air purification.展开更多
In order to obtain anatase TiO2/expanded graphite with high expansion volume, titania gel was introduced to expandable graphite surface by sol-gel process, and then the composite was expanded and calcined at high temp...In order to obtain anatase TiO2/expanded graphite with high expansion volume, titania gel was introduced to expandable graphite surface by sol-gel process, and then the composite was expanded and calcined at high tempera- ture. The samples were analysed by using scanning electron microscope （SEM）, X-ray diffraction（XRD）, energy disperse spectroscopy （EDS）, and differential scanning calorimetry （DSC）. The optimal conditions for preparation are as follows： the molar ratio of tetrabutyl orthotitanate to triethanolamine is 1 ： 0.4, and the calcination and expansion temperature is in the range of 650--750 ~C. Under such conditions, the expansion volume of composites could reach 98 mE/g, and the mass loss ratio is less than 5%. The analysis shows that lower temperature and smaller particle size of graphite are helpful to the formation of anatase-type of TiO2, but larger particle size will lead to lower mass loss ratio, and higher temperature and larger particle size will lead to higher expansion volume.展开更多
Catalytic degradation of cellulose to chemicals is an attracting topic today for the conver- sion of biomass, and the development of novel catalysts is a key point. Since metal-organic frameworks （MOFs） possess unif...Catalytic degradation of cellulose to chemicals is an attracting topic today for the conver- sion of biomass, and the development of novel catalysts is a key point. Since metal-organic frameworks （MOFs） possess uniform, continuous, and permeable channels, they are valu- able candidate as catalysts. Here, a new 3D MOF/graphene catalyst was prepared by in situ growth of the zeolitic imidazolate frameworks （ZIF-8） nanoparticles inside the pore of an as-formed 3D reduced graphene oxide （rGO） hydrogel. The ZIF-8/rGO nanocomposite owns both micropores and mesopores with large specific surface area and plenty of acids sites, which is an idea catalyst for biomass degradation. Cellulose was dissolved in allmline aqueous solution at first, and then it was degraded efficiently over the new catalyst under hydrothermal condition. The conversion reaches 100% while the main products are formic acid with a maximum yield of 93.66%. In addition, the catalyst can be reused with high activity.展开更多
Graphene aerogels are desirable for energy storage and conversion, as catalysis supports, and as adsorbents for environmental remediation. To produce graphene aerogels with low density, while maintaining high electric...Graphene aerogels are desirable for energy storage and conversion, as catalysis supports, and as adsorbents for environmental remediation. To produce graphene aerogels with low density, while maintaining high electrical conductivity and strong mechanic performance, we synthesized graphene aerogels by the magnesiothermic reduction of a freeze-dried graphene oxide （GO） self-assembly and subsequent etching of the formed MgO in acid solution. The reduced graphene oxide （rGO） aerogel samples exhibited densities as low as 1.1 mg·cm^-3. The rGO aerogel was very resilient, exhibiting full recoveryeven after being compressed by strains of up to 80%; its elastic modulus （E） scaled with density （p） as E-p^2. The rGO aerogels also exhibited high conductivities （e.g., 27.7 S·m^-1 at 3.6 mg·cm^-3） and outperformed many rGO aerogels fabricated by other reduction processes. Such outstanding properties were ascribed to the microstructures inherited from the freeze-dried GO self-assembly and the magnesiothermic reduction process.展开更多
Cell microcarriers have emerged as a powerful cell culture platform in biomedical areas, but their functions are usually limited to simply capturing and proliferating cells,because of the simplicity of their component...Cell microcarriers have emerged as a powerful cell culture platform in biomedical areas, but their functions are usually limited to simply capturing and proliferating cells,because of the simplicity of their components. Thus, in this study, we developed a new near-infrared（NIR） light-responsive graphene oxide（GO） hydrogel microcarrier system for controllable cell culture. The microcarriers were generated by using capillary microfluidics to emulsify the GO dispersed poly（N-isopropylacrylamide）（pNIPAM） and gelatin methacrylate（GelMA） pre-gel solution. The composite GO hydrogel microcarriers exhibited photothermally responsive cell capture, as well as the capacity for proliferation and release due to the NIR absorption of GO, the thermally responsive shape transition of pNIPAM, and the high biocompatibility of Gel MA. It was found that the NIR-responsive GO hydrogel microcarriers could prevent the cultured cells from being attacked by the immune system and promote the formation of tumor models in immunocompetent mice, which is desired for tumor and drug research. These features make the NIR-responsive GO hydrogel microcarriers excellent functional materials for different biomedical applications.展开更多
文摘以天然鳞片石墨为原料,采用改良的Hummers方法,制备了高纯度的薄层或单层氧化石墨(GO);并以抗坏血酸为还原剂,通过自组装还原的方式成功制备了具有三维多孔独巨石结构的还原氧化石墨烯(r GO)气凝胶,其形貌和结构经FT-IR,SEM,TEM,XRD和XPS表征。并对其作为锂离子电池负极材料的电化学性能进行了测试。结果表明:r GO气凝胶独特的形貌和结构提高了其比容量和循环性能,在100 m A·g-1电流密度下首周放电比容量可达1 700 m Ah·g-1,首周充电比容量达710 m Ah·g-1,经过100周循环后放电比容量仍可保持在450 m Ah·g-1,库伦效率保持在98%。
文摘Photocatalysis is considered a promising technique for removal of pollutants from indoor air.However,the low selectivity and limited recyclability of photocatalysts in powder form currently limit their practical application.In this work,we reported the successful preparation of a monolithic tungsten oxide(WO3)/graphene oxide(GO)aerogel photocatalyst through a cost‐effective freeze‐drying method.GO not only acts as a macroscopic support,but also increases the catalyst surface area from 46 to 57 m2/g,enhances the light absorption in the visible‐light region,and raises the separation efficiency of photogenerated electron‐hole pairs.The Obtained WO3/GO aerogel exhibited an outstanding visible‐light photocatalytic degradation rate of nitric oxide of 51%,which was 3.3 times that of pristine WO3 powder.In addition,the aerogel displayed excellent selectivity,with a generation fraction of toxic nitrogen dioxide of as low as 0.5%.This work presents a facile synthesis route to fabricate a monolithic WO3/GO aerogel photocatalyst with great promise for air purification.
基金Supported by Applied Basic Research Project of Sichuan Province (No.2006J13-014)Innovation Fund of Panzhihua University
文摘In order to obtain anatase TiO2/expanded graphite with high expansion volume, titania gel was introduced to expandable graphite surface by sol-gel process, and then the composite was expanded and calcined at high tempera- ture. The samples were analysed by using scanning electron microscope （SEM）, X-ray diffraction（XRD）, energy disperse spectroscopy （EDS）, and differential scanning calorimetry （DSC）. The optimal conditions for preparation are as follows： the molar ratio of tetrabutyl orthotitanate to triethanolamine is 1 ： 0.4, and the calcination and expansion temperature is in the range of 650--750 ~C. Under such conditions, the expansion volume of composites could reach 98 mE/g, and the mass loss ratio is less than 5%. The analysis shows that lower temperature and smaller particle size of graphite are helpful to the formation of anatase-type of TiO2, but larger particle size will lead to lower mass loss ratio, and higher temperature and larger particle size will lead to higher expansion volume.
文摘Catalytic degradation of cellulose to chemicals is an attracting topic today for the conver- sion of biomass, and the development of novel catalysts is a key point. Since metal-organic frameworks （MOFs） possess uniform, continuous, and permeable channels, they are valu- able candidate as catalysts. Here, a new 3D MOF/graphene catalyst was prepared by in situ growth of the zeolitic imidazolate frameworks （ZIF-8） nanoparticles inside the pore of an as-formed 3D reduced graphene oxide （rGO） hydrogel. The ZIF-8/rGO nanocomposite owns both micropores and mesopores with large specific surface area and plenty of acids sites, which is an idea catalyst for biomass degradation. Cellulose was dissolved in allmline aqueous solution at first, and then it was degraded efficiently over the new catalyst under hydrothermal condition. The conversion reaches 100% while the main products are formic acid with a maximum yield of 93.66%. In addition, the catalyst can be reused with high activity.
基金This work was supported Foundation for Returned Education of China, Key by the Scientific Research Scholars, the Ministry of Basic Research Projects of Science and Technology Commission of Shanghai （No.11JC1412900）, and the National Science Foundation of China program （Nos. 21271140, 51472182）.
文摘Graphene aerogels are desirable for energy storage and conversion, as catalysis supports, and as adsorbents for environmental remediation. To produce graphene aerogels with low density, while maintaining high electrical conductivity and strong mechanic performance, we synthesized graphene aerogels by the magnesiothermic reduction of a freeze-dried graphene oxide （GO） self-assembly and subsequent etching of the formed MgO in acid solution. The reduced graphene oxide （rGO） aerogel samples exhibited densities as low as 1.1 mg·cm^-3. The rGO aerogel was very resilient, exhibiting full recoveryeven after being compressed by strains of up to 80%; its elastic modulus （E） scaled with density （p） as E-p^2. The rGO aerogels also exhibited high conductivities （e.g., 27.7 S·m^-1 at 3.6 mg·cm^-3） and outperformed many rGO aerogels fabricated by other reduction processes. Such outstanding properties were ascribed to the microstructures inherited from the freeze-dried GO self-assembly and the magnesiothermic reduction process.
基金supported by the National Natural Science Foundation of China (21473029 and 51522302)the NSAF Foundation of China (U1530260)+3 种基金the Scientific Research Foundation of Southeast Universitythe Scientific Research Foundation of Graduate School of Southeast Universitythe Postgraduate Research & Practice Innovation Program of Jiangsu Provincethe Fundamental Research Funds for the Central Universities
文摘Cell microcarriers have emerged as a powerful cell culture platform in biomedical areas, but their functions are usually limited to simply capturing and proliferating cells,because of the simplicity of their components. Thus, in this study, we developed a new near-infrared（NIR） light-responsive graphene oxide（GO） hydrogel microcarrier system for controllable cell culture. The microcarriers were generated by using capillary microfluidics to emulsify the GO dispersed poly（N-isopropylacrylamide）（pNIPAM） and gelatin methacrylate（GelMA） pre-gel solution. The composite GO hydrogel microcarriers exhibited photothermally responsive cell capture, as well as the capacity for proliferation and release due to the NIR absorption of GO, the thermally responsive shape transition of pNIPAM, and the high biocompatibility of Gel MA. It was found that the NIR-responsive GO hydrogel microcarriers could prevent the cultured cells from being attacked by the immune system and promote the formation of tumor models in immunocompetent mice, which is desired for tumor and drug research. These features make the NIR-responsive GO hydrogel microcarriers excellent functional materials for different biomedical applications.
