Rajbhandari Rinita, Shrestha Lok Kumar, Pokharel Bhadra Prasad, Pradhananga Raja Ram
Department of Science and Humanities, Institute of Engineering, Tribhuvan University, Pulchowk Campus, Kathmandu 44613, Nepal.
J Nanosci Nanotechnol. 2013 Apr;13(4):2613-23. doi: 10.1166/jnn.2013.7373.
Series of activated carbons (ACs) have been prepared from Lapsi (Choerospondias axillaris) seed powder (LSP) by chemical activation with zinc chloride (ZnCI2) and the effects of ZnCl2 impregnation ratio, carbonization time, and precursor sources on the structure and properties of ACs have been systematically investigated. Carbonization was carried out at 400 degrees C and the ratio of LSP and ZnCI2 was varied from LSP:ZnCl2 = 1:0.25 (AC-0.25), 1:0.50 (AC-0.50) 1:1 (AC-1), 1:2 (AC-2), and 1:4 (AC-4). The ACs were characterized by Fourier transform-infrared (FTIR) spectroscopy, Raman scattering, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Surface properties (effective surface areas, pore volumes, and pore size distributions) were studied by nitrogen adsorption-desorption measurements. The electrochemical and vapor sensing properties were investigated by cyclic voltammetry, and quartz crystal microbalance (QCM) method, respectively. All the ACs are amorphous materials containing oxygenated surface functional groups and having nanoporous (microporous and mesoporous) structures. We found that surface properties depend on the LSP:ZnCI2 ratio, carbonization time, and also on the precursor type. The effective surface area increased significantly with increasing LSP:ZnCI2 ratio from 1:0.25 to 1:0.5 and then remain apparently constant. However, total pore volume increased continuously with ZnCI2 ratio. Increase in the carbonization time above 4 h decreased both the surface area and pore volume. ACs prepared from bamboo and coconut shell showed better surface properties compared to AC prepared from sugarcane; surface area and pore volume of the former systems are nearly double of the later system. AC derived from LSP (AC-4) showed excellent electrochemical performance giving specific capacitance value of 328 F/g in 1 M H2SO4 solution demonstrating the potential use of this material for supercapacitor electrodes. Our ACs showed good capability of molecule sensing of toxic solvent vapors such as carbon tetrachloride and pyridine.
通过用氯化锌（ZnCl₂）进行化学活化，由拉普西（南酸枣）种子粉末（LSP）制备了一系列活性炭（AC），并系统研究了ZnCl₂浸渍比、碳化时间和前驱体来源对AC结构和性能的影响。碳化在400℃下进行，LSP与ZnCl₂的比例从LSP:ZnCl₂ = 1:0.25（AC - 0.25）、1:0.50（AC - 0.50）、1:1（AC - 1）、1:2（AC - 2）和1:4（AC - 4）变化。通过傅里叶变换红外（FTIR）光谱、拉曼散射、X射线衍射（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）对AC进行表征。通过氮气吸附 - 脱附测量研究表面性质（有效表面积、孔体积和孔径分布）。分别通过循环伏安法和石英晶体微天平（QCM）方法研究电化学和气相传感性能。所有AC都是含有氧化表面官能团且具有纳米多孔（微孔和介孔）结构的无定形材料。我们发现表面性质取决于LSP:ZnCl₂比例、碳化时间，还取决于前驱体类型。有效表面积随着LSP:ZnCl₂比例从1:0.25增加到1:0.5而显著增加，然后明显保持恒定。然而，总孔体积随着ZnCl₂比例的增加而持续增加。碳化时间超过4小时会降低表面积和孔体积。与由甘蔗制备的AC相比，由竹子和椰壳制备的AC表现出更好的表面性质；前一种体系的表面积和孔体积几乎是后一种体系的两倍。源自LSP的AC（AC - 4）在1 M H₂SO₄溶液中表现出优异的电化学性能，比电容值为328 F/g，证明了这种材料在超级电容器电极方面的潜在用途。我们的AC对四氯化碳和吡啶等有毒溶剂蒸气表现出良好的分子传感能力。
