Composites of carbon aerogel and graphite oxide（GO） were synthesized using a self-assembly method based on dispersive forces. Their surface was modified by treatment in hydrogen sulfide at 650 and800 ℃. The samples...Composites of carbon aerogel and graphite oxide（GO） were synthesized using a self-assembly method based on dispersive forces. Their surface was modified by treatment in hydrogen sulfide at 650 and800 ℃. The samples obtained were characterized by adsorption of nitrogen, TA-MS, XPS, potentiometric titration, and HRTEM and tested as catalysts for oxygen reduction reactions（ORR） in an alkaline medium.The synergistic effect of the composite（electrical conductivity, porosity and surface chemistry） leads to a good ORR catalytic activity. The onset potential for the composite of carbon aerogel heated at 800 ℃ is shifted to a more positive value and the number of electron transfer was 2e-at the potential 0.68 V versus RHE and it increased to 4e-with an increase in the negative values of the potential. An excellent tolerance to methanol crossover was also recorded.展开更多
Herein, we report a simple and effective preparation of ultrafine CNFs （u-CNFs） with high surface area via electrospinning of two immiscible polymers [polyacrylonitrile （PAN） and poly（methyl methacry- late） （P...Herein, we report a simple and effective preparation of ultrafine CNFs （u-CNFs） with high surface area via electrospinning of two immiscible polymers [polyacrylonitrile （PAN） and poly（methyl methacry- late） （PMMA）] followed by calcination at high temperature in an inert atmosphere. Various electrospinning conditions were optimized in detail. Four different kinds of PAN/PMMA ratios （10/0, 7：3, 5：5 and 3：7） were chosen and found that the PAN/PMMA ratio of 3：7 （PAN/PMMA-3：7） is the optimum one. BET anal- ysis showed the specific surface area of the u-CNFs-3：7 was 46Z57 m2/g with an excellent pore volume （1.15 cms g-l） and an average pore size （9.48 nm）： it is about 25 times higher than the conventional CNFs （c-CNFs）. TEM and FE-SEM images confirmed the ultrafine structure of the CNFs with a thinner fiber di- ameter of-50 nm. The graphitic nature and atomic arrangement of the u-CNFs were investigated by Raman and XPS analyses. For the supercapacitor application, unlike the common electrode preparation methods, the u-CNFs-3：7 was used without any activation, chemical or mechanical modifications. The u-CNFs- 3：7 showed a better specific capacitance of 86 Fig in 1 mol/L 1-12S04 when compared to pure CNFs. The excellent physicochemical properties make the u-CNFs-3：7 an alternative choice to the existing CNFs for the supercapacitors.展开更多
基金supported by the Spanish Ministry of Economy and Competitiveness (Project CTQ2012-37925-C03-03)FEDER fundsby the Hungarian National Fund OTKA K109558
文摘Composites of carbon aerogel and graphite oxide（GO） were synthesized using a self-assembly method based on dispersive forces. Their surface was modified by treatment in hydrogen sulfide at 650 and800 ℃. The samples obtained were characterized by adsorption of nitrogen, TA-MS, XPS, potentiometric titration, and HRTEM and tested as catalysts for oxygen reduction reactions（ORR） in an alkaline medium.The synergistic effect of the composite（electrical conductivity, porosity and surface chemistry） leads to a good ORR catalytic activity. The onset potential for the composite of carbon aerogel heated at 800 ℃ is shifted to a more positive value and the number of electron transfer was 2e-at the potential 0.68 V versus RHE and it increased to 4e-with an increase in the negative values of the potential. An excellent tolerance to methanol crossover was also recorded.
基金supported by a research fund of Chungnam National University in 2014
文摘Herein, we report a simple and effective preparation of ultrafine CNFs （u-CNFs） with high surface area via electrospinning of two immiscible polymers [polyacrylonitrile （PAN） and poly（methyl methacry- late） （PMMA）] followed by calcination at high temperature in an inert atmosphere. Various electrospinning conditions were optimized in detail. Four different kinds of PAN/PMMA ratios （10/0, 7：3, 5：5 and 3：7） were chosen and found that the PAN/PMMA ratio of 3：7 （PAN/PMMA-3：7） is the optimum one. BET anal- ysis showed the specific surface area of the u-CNFs-3：7 was 46Z57 m2/g with an excellent pore volume （1.15 cms g-l） and an average pore size （9.48 nm）： it is about 25 times higher than the conventional CNFs （c-CNFs）. TEM and FE-SEM images confirmed the ultrafine structure of the CNFs with a thinner fiber di- ameter of-50 nm. The graphitic nature and atomic arrangement of the u-CNFs were investigated by Raman and XPS analyses. For the supercapacitor application, unlike the common electrode preparation methods, the u-CNFs-3：7 was used without any activation, chemical or mechanical modifications. The u-CNFs- 3：7 showed a better specific capacitance of 86 Fig in 1 mol/L 1-12S04 when compared to pure CNFs. The excellent physicochemical properties make the u-CNFs-3：7 an alternative choice to the existing CNFs for the supercapacitors.
