多孔碳材料的化学气相后处理及其超级电容性能

以廉价的椰壳为原料制备了高比表面积的多孔碳材料,然后在密闭的反应釜中以硝酸蒸汽对多孔碳材料进行了后处理,制备了亲水性更好的多孔碳材料。采用扫描透射电子显微镜(TEM)、物理吸附、X射线粉末衍射(XRD)、拉曼光谱(Raman)和接触角测试对材料的微观形貌、孔道结构、组成和亲水性进行了表征,探究了不同温度下硝酸蒸汽对多孔碳材料的形貌、结构的影响,并采用循环伏安法、恒电流充放电法和交流阻抗法考察了多孔碳材料的超级电容性能。结果表明,经过硝酸蒸汽处理后的多孔碳材料的比表面积和孔体积均有所降低,且随着处理温度的升高,降低得更加明显,而亲水性却越来越好。电化学测试结果表明,经过100℃硝酸蒸汽处理的多孔碳材料(CSC-100)具有最佳的超级电容性能。在以6 mol·L^-1 KOH为电解液的三电极体系中,当电流密度为0.5 A·g^-1时CSC-100的比电容可达452.9 F·g^-1,而未经硝酸蒸汽处理的多孔碳材料(CSC)的比电容仅为350.4 F·g^-1。电容贡献分析表明CSC-100良好的亲水性和表面官能团不仅提高了双电层电容,也提高了赝电容。

Porous Carbon Material: Post-treatment through Chemical Vapor Method and Supercapacitor Performance

Porous carbon with a high specific surface area was prepared using a cheap coconut shell as raw material,and then the porous carbons were treated with nitric acid vapor in a closed reactor to improve the hydrophilicity of carbons.Using scanning transmission electron microscopy(TEM),physical adsorption,X-ray powder diffraction(XRD),Raman spectroscopy,and contact angle tests to measure the morphology,pore structure,composition,and hydrophilicity of carbons.The influence of nitric acid vapor on the morphology and structure of porous carbon materials at different temperatures was explored.Cyclic voltammetry,galvanostatic charge and discharge,and electrochemical impedance methods were used to investigate the supercapacitor performance of porous carbon materials.The results showed that the specific surface areas and pore volumes of the porous carbon vapor were reduced after the post-treatment of nitric acid vapor,and the decrease was more obvious with the increase of the treatment temperature,while the hydrophilicity was getting better.Electrochemical test results showed that the porous carbon material(CSC-100)treated with 100℃nitric acid vapor had the best supercapacitor performance.In the three electrodes system with 6 mol·L^-1 KOH as the electrolyte,when the current density was 0.5 A·g^-1,the specific capacitance of CSC-100 can reach 452.9 F·g^-1,while the specific capacitance of untreated carbon(CSC)was only 350.4 F·g^-1.The capacitance contribution analysis shows that the good hydrophilicity and surface functional groups of CSC-100 increase not only the electric double-layer capacitance but also improve the pseudocapacitance.