碳气凝胶电极用于NaCI溶液电容性除盐的研究

碳气凝胶是一种新型多孔碳材料，具有比表面积大、电导率高的特点。本文通过常压干燥制备了碳气凝胶，研究测试了其结构特性，用NaCl溶液模拟海水，利用CDI原理，以碳气凝胶作电极进行了NaCl溶液的除盐实验。实验表明，决定碳气凝胶的除盐效果的主要因素为比表面积和电导率。在不同配比结构中，以R/C为1500、M值为30％的碳气凝胶电极的除盐效果最佳。利用双电层电容模型解释探讨了碳气凝胶电极的除盐机理。     

超盐环境下含氮碳气凝胶的制备及其在超级电容器中的应用

多孔碳材料因其优异的导电性和稳定性,以及成本低廉等优点而成为当今的研究热点之一。以苯酚、甲醛和三聚氰胺为原料,利用高浓度氯化锌来提供超盐环境,经溶剂热反应后,在氮气中800℃下热解制得了含氮碳气凝胶(NCA)。扫描电子显微镜、拉曼光谱、X射线光电子能谱和氮气吸附等表征结果表明,该含氮碳气凝胶具有分级多孔蜂窝状结构,其比表面积高达729.6 m2/g。采用三电极测试体系测试了含氮碳气凝胶的电化学性能,结果表明,在三电极体系中,以0.5 mol/L H₂SO₄作为电解液,含氮碳气凝胶在电流密度为1 A/g时比电容达到350.7 F/g;在电流密度为20 A/g时,经过10000次充放电后,含氮碳气凝胶的电容保持率仍高达97.8%。在双电极体系中,含氮碳气凝胶在800 W/kg的功率密度下,能量密度可达26.8 (W·h)/kg。上述结果表明,该含氮碳气凝胶是一种非常理想的超级电容器电极材料。     

超盐环境下含氮碳气凝胶的制备及其在超级电容器中的应用

多孔碳材料因其优异的导电性和稳定性,以及成本低廉等优点而成为当今的研究热点之一。以苯酚、甲醛和三聚氰胺为原料,利用高浓度氯化锌来提供超盐环境,经溶剂热反应后,在氮气中800℃下热解制得了含氮碳气凝胶(NCA)。扫描电子显微镜、拉曼光谱、X射线光电子能谱和氮气吸附等表征结果表明,该含氮碳气凝胶具有分级多孔蜂窝状结构,其比表面积高达729.6 m~2/g。采用三电极测试体系测试了含氮碳气凝胶的电化学性能,结果表明,在三电极体系中,以0.5 mol/L H_2SO_4作为电解液,含氮碳气凝胶在电流密度为1 A/g时比电容达到350.7 F/g;在电流密度为20 A/g时,经过10000次充放电后,含氮碳气凝胶的电容保持率仍高达97.8%。在双电极体系中,含氮碳气凝胶在800 W/kg的功率密度下,能量密度可达26.8 (W·h)/kg。上述结果表明,该含氮碳气凝胶是一种非常理想的超级电容器电极材料。     

间苯二酚—甲醛基碳气凝胶的制备及其应用

超级电容器是新型储能器件之一，电极材料是影响其性能的关键因素。以间苯二酚和甲醛为主要原料，采用反相悬浮聚合的方法，通过常压干燥和碳活化过程获得高比表面积的碳气凝胶材料。制备的碳气凝胶材料比表面积达到1 783.6 m2/g，具有丰富的微孔结构，其比电容达到122.4 F/g，作为3 000 F超级电容器的电极材料，经过循环充放电测试，证实其具有良好的循环稳定性。以常压干燥方式制备的碳气凝胶应用于超级电容器中，表现出的电化学性能优异，不仅提供了碳气凝胶产业化新思路，也表明碳气凝胶在储能领域具有非常广阔的应用前景。     

镍掺杂对碳气凝胶结构及电化学性能的影响

以间苯二酚、间苯三酚和甲醛为反应物,在硝酸镍存在下,经过溶胶-凝胶、溶剂置换、常压干燥及高温炭化制得镍掺杂碳气凝胶材料。利用N2吸附法、XRD及FE-SEM-EDΛX对碳气凝胶的结构和形貌进行表征,利用循环伏安法、恒流充放电方法对制得的镍掺杂碳气凝胶材料在6 mol/L KOH中的电化学性能进行评价。XRD和FE-SEM-EDΛX测试表明,金属镍成功地掺入到碳气凝胶结构中,随着镍质量分数的增大,碳气凝胶结构中出现较大的孔道;N2吸附-脱附数据表明,镍质量分数为0.5%时,比表面积、总孔容、介孔率较大,表明少量硝酸镍的存在,起到造孔的作用。循环伏安及恒流充放电测试表明,在0~0.8 V电位范围内,电极材料具有典型的双电层电容和充放电可逆性,当镍质量分数为0.5%,在0.5 A/g的电流密度下测得的比电容为134.4 F/g。     

SiO2气凝胶的非超临界干燥法制备与表征

以聚二甲基硅烷为原料,采用聚合物超临界法制备了SiO2气凝胶.聚合物超临界法制备的SiO2气凝胶除碳前为疏水性气凝胶,比表面积为27.68 m2/g,孔体积为0.103 7 cm3/g,平均孔径约为15 nm;除碳后为亲水性气凝胶,比表面积为500.6 m2/g,孔体积为0.404 3 cm3/g,平均孔径为3.23 nm.对聚合物超临界法制备SiO2气凝胶的反应机理进行了初步探讨.     

碳气凝胶军事应用技术研究进展

碳气凝胶具有特殊的微纳米多孔结构,孔隙率极高,使其表现出比表面积大、电导率高、密度极低、热导率低等显著特点,是一种很有前途的军用多功能材料,在许多军事应用领域展现出巨大的发展潜力。本文通过对中外文献的深入调研,介绍了研究人员在开发碳气凝胶在军事应用技术方面的最新研究成果,涉及超级电容器电极材料、烟幕材料、隐身材料、隔热材料和装甲防护材料等军事应用领域。     

直接甲醇燃料电池用碳气凝胶载铂催化剂的研究

利用溶胶—疑胶方法制备了高比表面积的碳气凝胶,利用浸渍还原法制备了Pt/碳气凝胶和Pt/C催化剂。采用BJH和TEM考察碳气凝胶的孔径分布和金属粒子的大小与分布,循环伏安曲线测试考察Pt/碳气凝胶对甲醇催化氧化性能的影响。结果表明,碳气凝胶的比表面积达到480 m2/g,孔径分布良好,催化剂金属颗粒较小,分散较好,循环伏安曲线图显示出Pt/碳气凝胶比传统的Pt/C对甲醇催化氧化性能高。     

壳聚糖碳气凝胶原位负载Fe_(3)O_(4)的制备及其电化学性能EI北大核心CSCD

以壳聚糖(CS)、FeCl_(3)·6H_(2)O为原料,通过原位生长制备了较高比电容的Fe_(3)O_(4)/CS碳气凝胶电极材料,改善了碳基材料比电容低的问题。采用X射线衍射仪、Raman光谱仪分析了样品的晶体结构和结构缺陷,通过X射线光电子能谱仪和扫描电子显微镜对样品的成分和形貌进行了表征,并在三电极体系中测试了其电化学性能。结果表明:Fe_(3)O_(4)成功地负载在CS碳气凝胶上,且两者之间具有良好的结合力。壳聚糖分子上的氨基在碳化过程中实现了N原子自掺杂,复合材料的N含量高达7.21%(摩尔分数)。此外,当在1.0 gCS中引入0.4 gFeCl_(3)·6H_(2)O时,在0.5 A/g的电流密度下复合碳气凝胶表现出315.5 F/g的比容量,与单纯CS碳气凝胶相比,比电容提升了约3倍。     

钴基气凝胶的制备及微观结构

以氯化钴为原料,聚丙烯酸(PAA)为模板剂制得了钴基复合气凝胶,通过场发射扫描电镜(FESEM)、高分辨透射电镜(HRTEM)、X射线衍射(XRD)、N2吸脱附以及红外谱图(FTIR)对气凝胶的结构进行了表征,结果表明:钴基复合气凝胶是由大量纳米级的球状颗粒堆积而成的,具有典型的三维网络结构,其骨架是由大量非晶态的碳层包覆的氧化钴胶体颗粒所组成的;气凝胶具有较高的比表面积为177 m2/g,孔径分布主要集中在4 nm左右,为介孔材料。通过退火处理后,钴基复合气凝胶中的有机物被完全氧化、分解,制备出了Co3O4气凝胶,其微观结构较为致密,具有立方的多晶结构,比表面积为54 m2/g,孔径分布主要集中在7 nm左右。     

添加剂PVB对炭气凝胶制备工艺及结构的影响

采用溶胶—凝胶法,以间苯二酚(R)、甲醛(F)为原料、无水碳酸钠(C)作催化剂、聚乙烯醇缩丁醛(PVB)为添加剂、无水乙醇作溶剂,通过常温常压干燥和高温炭化制备炭气凝胶。考察了中间产物有机凝胶的热解行为和催化剂浓度及PVB用量对炭气凝胶孔隙结构的影响。结果表明:PVB的加入不仅加强了有机凝胶的网络结构,使其更利于常温常压干燥,而且能够较好地调控炭气凝胶的孔径分布;在一定的PVB加入量范围内,随着PVB加入量的增加,炭气凝胶的比表面积增加,孔径分布也更加集中;催化剂浓度对炭气凝胶的比表面积及孔径分布有较大的影响,当R/C=300,PVB/R=1/10时比表面积达到最大值(386m~2/g)。     

二氧化碳活化法制备高比表面积碳气凝胶

以间苯二酚-甲醛为原料,常压干燥条件下制备传统的碳气凝胶,通过活化工艺成功地将其比表面积提高了3倍以上. 用比表面积测试及孔径分布、扫描电镜(SEM)等手段对其微观结构进行了表征并优化了工艺参数.     

从酚类合成新型炭材料—炭气凝胶

综述了炭气凝胶的制备方法、结构控制原理，分析了从煤焦化产品酚类原料出发合成这种炭材料的可行性     

碳气凝胶的常压干燥制备及结构控制

研究了碳气凝胶在常压条件下的制备过程和干燥方法. 用扫描电镜、比表面测量仪及孔径分布仪对其结构进行了表征与测试. 通过改变催化剂和溶剂的用量,可以实现碳气凝胶的颗粒直径及孔洞由纳米到微米级的连续调节. 通过降低催化剂浓度并以丙酮进行溶剂替换,成功实现了碳气凝胶的常压干燥. 常压干燥样品具有250~650 kg/m3的低密度和250~550 m2/g的高比表面积. 分析了其溶胶-凝胶反应机理,围绕毛细压力和材料强度等方面探讨了其常压干燥的实现途径.     

Fabrication and nano-structure control of carbon aerogels via a microemulsion-templated sol-gel polymerization method

Carbon aerogels were successfully fabricated by a microemulsion-templated sol-gel polymerization method. When a suitable molar ratio of surfactant to resorcinol (S/R) and an appropriate resorcinol-formaldehyde concentration were selected, the organic gels thus obtained could be dried with little shrinkage by heating at ambient pressure. The size of carbon nano-particles and the pore size of carbon aerogels thus produced decrease with an increase of S/R. The highest specific surface area and specific mesopore volume of the carbon aerogels prepared by our method were 620 m² g⁻¹ and 1.14 cm³/g, respectively.     

Carbon Aerogels for Electrochemical Double Layer Capacitors

Carbon aerogels are prepared here via pyrolysis of resorcinol-formaldehyde aerogels. Their open porous and electrically conductive structure renders carbon aerogels suitable for the application in supercapacitors. Different types of electrodes can be derived from the sol-gel-precursors of carbon aerogels: Monolithic fibre-reinforced electrodes and polymer-carbon compounds. Both carbon fibre reinforced and polymeric bound aerogel electrodes based on polytetrafluoroethylene (PTFE) have been investigated in this work with respect to their electrical conductivity, surface area and capacitive performance. The capacitance of both electrode types is above 65 F/cm³ in aqueous electrolytes and this meets the demands of supercapacitor electrodes.     

Carbon aerogels for catalysis applications: An overview

Carbon aerogels are nanostructured carbons obtained from the carbonization of organic aerogels, which are prepared from the sol-gel polycondensation of certain organic monomers. These materials have a great versatility both at the nanoscopic level in terms of their pore texture and at the macroscopic level in terms of their form. Thus, the surface area, pore volume, and pore size distribution are tuneable surface properties related to the synthesis and processing conditions, which can produce a wide spectrum of materials with unique properties. In addition, carbon aerogels can be obtained in the form of monoliths, beads, powders or thin films. All these properties make them promising materials for application in adsorption and catalysis. Metal-doped monolithic organic aerogels can be easily prepared by following three main strategies: by addition of the metal precursor to the initial mixture, by ion-exchange or by deposition of the metal precursor on the organic or the carbon aerogel by one of various methods. These metal-doped carbon aerogels have been used as catalysts and as electrodes for electrical double-layer capacitors. This article shows the preparation of metal-doped carbon aerogels, their physico-chemical surface properties and their applications as catalysts in various reactions.     

Filamentous carbon templated SiO2–NiO aerogel: structure and catalytic properties for direct oxidation of hydrogen sulfide into sulfur

Silica aerogels comprising nickel oxide nanoparticles were synthesized with no use of supercritical drying. A high specific surface area (more than 1000 m²/g), mesoporous structure and considerable stability to sintering up to 900 °C are characteristic of these aerogels. The aerogels were synthesized using the sol–gel method. Filamentous carbon was templated by silica, tetraethoxysilane being used for supplying silica. Carbon was burnt later. Analysis of the aerogel structure revealed the presence of silica nanotubes and nanofibers. Aerogel testing for direct oxidation of H₂S into S⁰ demonstrated as high as 60% conversion of hydrogen sulfide at almost 100% selectivity under stoichiometric conditions at the temperature range of 300–350 °C and 73% conversion at 100% selectivity at a considerable excess of oxygen at 160 °C. This revised version was published online in July 2006 with corrections to the Cover Date.     

Nanoporous phloroglucinol-formaldehyde carbon aerogels for electrochemical use

Phloroglucinol-Formaldehyde (PF) organic aerogels were prepared from alcoholic sol-gel polycondensation of phloroglucinol with formaldehyde using KOH as base catalyst and followed by supercritical drying with carbon dioxide. Subsequent pyrolysis of PF organic aerogel under He flow produced carbon aerogels. Textural properties of PF organic and carbon aerogels were obtained by nitrogen adsorption-desorption, and their specific capacitances were measured by cyclic voltammetry. The resultant PF carbon aerogels were mostly mesoporous material with high surface area. The nanoporous structure and electrochemical behavior of PF carbon aerogels could be controlled by the molar ratio of phloroglucinol to catalyst (P/C) and carbonization conditions. PF carbon aerogels exhibited the highest surface area in excess of 1,200 m²/g and specific capacitance up to 250 F/g in comparison to other carbons.