活性炭二次活化对其电化学容量的影响（英文）

为进一步提高作为电化学超级电容器电极材料活性炭的电化学容量,采用KOH作为二次活性剂,将所得活性炭进行二次化学活化处理,从而得到二次活化活性炭.将原始活性炭材料与二次活化活性炭材料都分别经过系列处理,组装成电化学超级电容器进行电化学性能测试.测试结果表明,二次活化活性炭材料的电化学容量达到145.0F·g-1（有机电解液）,远远大于原活性炭材料的容量（45.0F·g^-1）.为研究二次活化活性炭材料电化学容量大幅提高的原因,将这两种材料分别进行微观结构数据测试,包括比表面积、N2吸脱附等温曲线和孔径分布.研究结果表明,二次活化处理大大增加了二次活化活性炭材料在孔径为2-3nm的中孔分布,从而证实对于有机电解液,电极材料在2-3nm的中孔对其电化学容量的提高具有重要意义.     

活性炭二次活化对其电化学容量的影响

为进一步提高作为电化学超级电容器电极材料活性炭的电化学容量, 采用KOH作为二次活性剂, 将所得活性炭进行二次化学活化处理, 从而得到二次活化活性炭. 将原始活性炭材料与二次活化活性炭材料都分别经过系列处理, 组装成电化学超级电容器进行电化学性能测试. 测试结果表明, 二次活化活性炭材料的电化学容量达到145.0 F·g-1(有机电解液), 远远大于原活性炭材料的容量(45.0 F·g-1). 为研究二次活化活性炭材料电化学容量大幅提高的原因, 将这两种材料分别进行微观结构数据测试, 包括比表面积、N2吸脱附等温曲线和孔径分布. 研究结果表明, 二次活化处理大大增加了二次活化活性炭材料在孔径为2-3 nm的中孔分布, 从而证实对于有机电解液, 电极材料在2-3 nm的中孔对其电化学容量的提高具有重要意义.     

离子液体电解质种类对活性炭电极超级电容器电化学性能的影响

本文将经水蒸气二次活化的椰壳活性炭（W-AC）作为电极材料,选择1-乙基-3甲基咪唑四氟硼酸盐（[EMIM]BF₄）作为电解质,结果表明W-AC电极的比电容量远高于未活化的椰壳活性炭（R-AC）.使用循环伏安、恒电流充放电、交流阻抗等方法研究了不同种类离子液体电解质对超级电容器电化学性能的影响.不同阴阳离子组成的离子液体作为电解质,直接影响超级电容器的电化学性能. 研究表明,由EMIM⁺和BMIM⁺阳离子与BF₄^-、TFSI^-阴离子构成的离子液体电解质较适用于W-AC电极. 其中在[EMIM]BF₄电解质中,单片电极的比电容量可高达153 F·g^-1;在1-丁基-3-甲基-咪唑四氟硼酸盐（[BMIM]BF₄）电解质中电位窗可达3.5V,能量密度可高达57 Wh·kg^-1.本研究对于构筑高性能超级电容器离子液体的选择提供参考,以满足不同应用领域需求.     

碳基双电层电容器的结构、机理及研究进展

活性炭基双电层电容器是一种新型电化学能量储存装置,其储电机理是利用电极材料比较大的比表面积在电极和电解液之间形成双电层储存电荷,充放电过程中无化学反应发生。活性炭材料由于具有较大的比表面积、良好的孔结构分布、化学惰性表面等,一直是双电层电容器电极的首选材料。本文简要介绍了双电层电容器的制造工艺、应用及发展趋势。     

高能量密度和功率密度炭电极材料

以核桃壳为原料, 采用同步物理-化学活化法制备活性炭(AC). 用氮气吸附法和傅立叶红外光谱(FTIR), 对活性炭的孔结构和表面官能团进行了分析. 以活性炭为电极材料制备炭电极, 6 mol·L-1 KOH溶液为电解液组装成超级电容器, 利用恒电流充放电、循环伏安、交流阻抗等电化学测试方法研究其电化学性能及其与活性炭材料结构的关系. 结果表明, 实验电容器的内电阻、漏电流小, 循环充放电稳定性好, 容量保持率高; 活性炭的比电容随比表面积的增加而增大, 且与BET比表面积呈线性相关; 孔径在1.5-4 nm之间的孔表面有利于形成有效的双电层. 中等比表面积1197 m2·g-1炭样的比电容高达292 F·g-1, 80 mA充放电时, 电容器能量密度高达7.3 Wh·kg-1, 功率密度超过770 W·kg-1,峰值功率密度为5.1 W·g-1.     

炭化温度对烟杆基活性炭孔结构及电化学性能的影响研究

以烟杆为原料, 氢氧化钾为活化剂, 通过调节炭化温度(500～800 ℃温度范围)在相同活化条件下制备了具有不同孔隙结构的活性炭材料. N₂吸附测试表明随着炭化温度降低, 活性炭的比表面积和总孔容先增大后减小, 中孔比表面积和平均孔径却一直增大. 其中600 ℃炭化样品经KOH活化后可制得比表面积为3333 m²•g^－1, 总孔容为2.47 cm³• g^－1, 中孔孔容达2.11 cm³•g^－1的高中孔率高比表面积活性炭材料. 采用直流充放电法、交流阻抗法和循环伏安法测定上述多孔炭为电极材料的双电层电容器的电化学性能, 结果表明: 炭化温度不同的烟杆基活性炭电极均表现出良好的功率特性, 充放电流增大50倍, 容量保持率均在80%左右, 其中TS-AC-600活性炭电极在有机电解液中1 mA•cm^－2充放电时, 比电容达到190 F•g^－1. 较高的中孔率和较大的平均孔径使得烟杆基活性炭电极具有良好的高倍率充放电性能.     

高比能超级电容器的研究进展

与传统蓄电池相比,超级电容器具有高功率密度、长循环寿命和使用温度范围宽等优势,但其能量密度较低.本文对超级电容器的结构、分类以及发展状况进行了简要介绍,重点阐述了本实验室近年来在研制高性能超级电容器方面的相关工作.主要从两个方面来提高超级电容器的能量密度:(1)通过采用中性水系电解液、有机电解液和离子液体提高对称型碳基超级电容器的电压窗口;(2)应用非对称型超级电容器,即一个电极采用具有法拉第赝电容电极材料或电池电极材料,而另一个电极则采用具有双电层电容的电极材料.同时介绍了由锂离子电池电极材料/活性炭作为正极,石墨作为负极组成的锂离子混合型超级电容器.最后,对超级电容器的发展方向进行了展望.     

氧化镍/碳纳米管复合型超级电容器的研制

通过电化学阴极还原的方法制备了氧化镍电极材料。经250℃脱水处理后氧化镍材料表现出法拉第赝电容的电化学特性且材料单电极比容量达到210F·g^-1，优于普通活性炭材料。本文采用催化裂解法制备了碳纳米管电极材料，比容量达到了42F·g^-1。提出了采用电化学法沉积氧化镍和碳纳米管分别作为电容器正负极的新工艺，该工艺制备的复合型超级电容器的工作电位达到了1.6V，且具有良好的大电流放电特性。实验还表明该型氧化镍超级电容器具有极低的自放电率。     

高容量超级电容器电极材料的设计与制备

超级电容器寿命长,安全性高,并可以实现快速充放电,是化学电源研究的热点之一。然而,超级电容器的能量密度较低限制了其更多的应用。因此,超级电容器领域的研究关注点在如何提高超级电容器的能量密度。其中,提高比容量是提高能量密度的一种有效途径。本文通过对电极材料和电解液的优化来研究制备得到高容量超级电容器的方法。电极材料的比表面积、孔道结构和导电性对其电化学性能有着直接的影响。一方面,通过优化电极材料的孔道结构和比表面积可以增加活性位点并提高电解液离子传导率,从而得到高比电容。另一方面,电极材料导电性的提高有利于提升其电子传导率从而得到较高的比容量。本文分别对碳材料和金属氧化物/氢氧化物的优化达到了增加双电层电容和赝电容的目的。不仅如此,还可以通过在电解液中增加氧化还原电对从而得到高比电容。这一方法为高容量超级电容器的制备提供了新的思路。     

有序介孔碳的简易模板法制备与电化学电容性能研究

0引言电化学电容器(Electrochemical Capacitors),又称为超级电容器(supercapacitors)是介于传统电容器和二次电池之间的一种新型储能装置,它具有循环寿命长、比容量高、能快速充放电等优点[1,2]。近年来随着电子、电气设备的日趋小型化以及电动汽车工业的不断发展,作为后备电源和记忆候补装置的超级电容器日益引起了人们的广泛关注。碳材料由于具有成本低、比表面积大、导电性优良、制备电极工艺简单等特点,一直是超级电容器电极材料的首选。其中,活性炭是最早采用的多孔电极材料,其比表面积可高达2500￣3000m·2g-1[3]。然而,活性炭材料…     

电化学双电层电容器用新型炭材料及其应用前景

活性炭是目前使用最为广泛的一种电化学双电层电容器（EDLC）的电极材料,但其固有的缺点制约了EDLC性能的进一步提高。用新型高性能炭电极材料可使EDLC比能量和比功率性能进一步提高。这些新型炭材料包括基于石墨层状结构的纳米门炭,基于碳纳米管阵列结构的毛皮炭,通过高温置换反应制备的骨架炭以及电极可整体成型的纳米孔玻态炭。本文介绍了这些炭材料的电化学特性及其在电化学双电层电容器中的应用,指出用这4种新型炭材料制备EDLC的比能量或比功率性能远高于目前活性炭基EDLC,具有良好的应用前景。     

ACTIVATION ENERGY OF DESORPTION OF DIBENZOFURAN ON ACTIVATED CARBONS

Three kinds of commercial activated carbons, such as Norit RBI, Monolith and Chemviron activated carbons, were used as adsorbents for adsorption of dibenzofiuran. The average pore size and specific surface area of these activated carbons were measured Temperature Programmed Desorption (‘TPD) experiments were conducted to measure the TPD curves of dibenzofuran on the activated carbons, and then the activation energy for desorption of dibenzofuran on the activated carbons was estimated. The results showed that the Chemviron and the Norit RB1 activated carbon maintained higher specific surface area and larger micropore pore volume in comparison with the Monolith activated carbon, and the activation energy for the desorption of dibencofuran on these two activated carbons was higher than that on the Monolith activated carbon. The smaller the pore of the activated carbon was, the higher the activated energy of dibenzofiuran desorption was.     

ACTIVATION ENERGY OF DESORPTION OF DIBENZOFURAN ON ACTIVATED CARBONS

1. INTRODUCTION With the development of municipalization in China, more and more cities are challenged by the problem of how to dispose of the dramatically increased municipal waste. Generally, most of municipal solid waste is landfilled or dumped openly in the suburbs. It causes not only land waste, but also serious environment pollution. In order to solve efficiently the environment pollution caused by municipal solid waste, incineration technique was introduced in some big cities such…     

Adsorption of sodium dodecylbenzenesulfonate on activated carbons: effects of solution chemistry and presence of bacteria

The objective of the present investigation was to determine the effectiveness of activated carbon in removing sodium dodecylbenzenesulfonate (SDBS) and to analyze the chemical and textural characteristics of the activated carbons that are involved in the adsorption process. Studies were also performed on the influence of operational variables (pH, ionic strength, and presence of microorganisms) and on the kinetics and interactions involved in the adsorption of this pollutant on activated carbon. The kinetics study of SDBS adsorption revealed no problems in its diffusion on any of the activated carbons studied, and Weisz-Prater coefficient (C WP) values were considerably lower than unity for all activated carbons studied. SDBS adsorption isotherms on these activated carbons showed that: (i) adsorption capacity of activated carbons was very high (260-470 mg/g) and increased with larger surface area; and (ii) dispersive interactions between SDBS and carbon surface were largely responsible for the adsorption of this pollutant. SDBS adsorption was not significantly affected by the solution pH, indicating that electrostatic adsorbent-adsorbate interactions do not play an important role in this process. The presence of electrolytes (NaCl) in the medium favors SDBS adsorption, accelerating the process and increasing adsorption capacity. Under the working conditions used, SDBS is not degraded by bacteria; however, the presence of bacteria during the process accelerates and increases SDBS adsorption on the activated carbon. Microorganism adsorption on the activated carbon surface increases its hydrophobicity, explaining the results observed.     

Oxygen reduction on carbon nanomaterial-modified glassy carbon electrodes in alkaline solution

Electroreduction of oxygen in alkaline solution on glassy carbon (GC) electrodes modified with different carbon nanomaterials has been studied. Electrochemical experiments were carried out in 0.1 M KOH employing the rotating disk electrode and rotating ring-disk electrode methods. The GC disk electrodes were modified with carbon nanomaterials using polytetrafluoroethylene as a binder. Four different carbon nanomaterials were used: multiwalled carbon nanotubes, carbon black powder, and two carbide-derived carbons (CDC). For the first time, the electrocatalytic behavior of CDC materials toward oxygen reduction is explored. Electrochemical characterization of the materials showed that all the carbon nanomaterial-modified GC electrodes are highly active for the reduction of oxygen in alkaline solutions.     

Cadmium ion adsorption on different carbon adsorbents from aqueous solutions. Effect of surface chemistry, pore texture, ionic strength, and dissolved natural organic matter

Adsorption of Cd(II) species at pH = 5 was studied on three carbon adsorbents: granular activated carbon, activated carbon fiber, and activated carbon cloth. As-received and oxidized adsorbents were used. Cd(II) adsorption greatly increased after oxidation due to the introduction of carboxyl groups. The use of a buffer solution to control the pH introduced some changes in the surface chemistry of carbons through the adsorption of one of the compounds used, biphthalate anions. The increase in ionic strength reduced Cd(II) uptake on both as-received and oxidized carbons due to a screening of the electrostatic attractions between the Cd(II) positive species and the negative surface charge, which in the case of as-received carbons derived from the biphthalate anions adsorbed and in the oxidized ones from the carboxyl groups. Tannic acid was used as a model compound for natural organic matter. Its adsorption was greatly reduced after oxidation, and most of the carbon adsorbents preadsorbed with tannic acid showed an increase in Cd(II) uptake. In the case of competitive adsorption between Cd(II) species and tannic acid molecules, there was a decrease in Cd(II) uptake on the as-received carbon whereas the contrary occurred with the oxidized carbons. These results illustrate the great importance of carbon surface chemistry in this competitive adsorption process. Finally, under all experimental conditions used, when the adsorption capacity of carbons was compared under the same conditions it increased in the following order: granular activated carbon < activated carbon fiber < activated carbon cloth.     

活性炭的孔径分布对CH4和CO2的吸附性能的影响

采用不同炭化温度和活化温度,以椰壳作为前驱体制备了系列结构性能相同,表面吸附基团相似,不同孔结构的活性炭。分别采用密度函数理论(DFT)吸附法和BJH估算了系列活性炭的孔径分布。结果表明,随炭化温度和活化温度的升高系列活性炭中微孔量先增加后减少。当炭化温度为700 ℃,活化温度为800 ℃时,制备的活性炭微孔量达到最大。随炭化温度和活化温度的升高,系列活性炭的中孔依次增加。考查了CH₄,CO₂在系列活性炭上的吸附性能。结果表明该系列活性炭对CO₂有很强的吸附能力,在常温常压下对CO₂的吸附量均高于1.0 mmol·g^-1;系列活性炭对CH₄的吸附能力有较大的差异,在对CO₂具有最大吸附量的活性炭上对CH₄具有最小的吸附量。采用变压吸附法测试了该系列活性炭在25 ℃时对n_CH4∶n_CO2=9∶1的混合气体的分离性能。结果表明炭化温度为700 ℃,活化温度为800 ℃时制备的活性炭对CH₄-CO₂混合气具有最好的分离效果,是变压吸附分离CH₄,CO₂混合气的优异吸附剂。     

Cyclodextrins adsorbed onto activated carbons: preparation, characterization, and effect on the dispersibility of the particles in water

We have investigated the adsorption equilibrium of selected cyclodextrins onto activated carbons. A number of parameters were examined including the type of carbon material, the size of macrocyclic cavity, and the chemical nature of the oligosaccharide (e.g., neutral, anionic, or cationic cyclodextrin). Adsorption isotherm studies revealed that the maximum amount of cyclodextrin immobilized on the carbon surface is obtained for the native β-CD, while the adsorption capacity of the ionic cyclodextrins derivatives strongly depends on the net surface charge of the activated carbon. The affinity of cyclodextrins for activated carbons was further utilized to prepare modified activated carbons containing controlled amounts of cyclodextrins through an adsorption process. The resulting materials were characterized by N(2) adsorption-desorption volumetric measurements, FTIR and Raman spectroscopy, while the quantitative determination of the oligosaccharide content on activated carbons was performed by gravimetric measurements. On the basis of the Turbiscan results, it was found that the chemical structure of cyclodextrins, which are incorporated in the carbon framework, had significant influence on the dispersibility and stabilization of the solid particles in water. Agglomeration and precipitation of the carbon particles were markedly suppressed with substituted cyclodextrins whose hydroxyl groups were partially substituted by methyl or alkylammonium groups.     

Preparation of highly porous carbon from fir wood by KOH etching and CO2 gasification for adsorption of dyes and phenols from water

Fir wood was first carbonized for 1.5 h at 450 degrees C, then soaked in a KOH solution KOH/char ratio of 1, and last activated for 1 h at 780 degrees C. During the last hour CO2 was poured in for further activation for 0, 15, 30, and 60 min, respectively. Carbonaceous adsorbents with controllable surface area and pore structure were chemically activated from carbonized fir wood (i.e., char) by KOH etching and CO2 gasification. The pore properties, including the BET surface area, pore volume, pore size distribution, and pore diameter, of these activated carbons were first characterized by the t-plot method based on N2 adsorption isotherms. Fir-wood carbon activated with CO2 gasification from 0 to 60 min exhibited a BET surface area ranging from 1371 to 2821 m2 g(-1), with a pore volume significantly increased from 0.81 to 1.73 m2 g(-1). Scanning electron microscopic (SEM) results showed that the surfaces of honeycombed holes in these carbons were significantly different from those of carbons without CO2 gasification. The adsorption of methylene blue, basic brown 1, acid blue 74, p-nitrophenol, p-chlorophenol, p-cresol, and phenol from water on all the carbons studied was examined to check their chemical characteristics. Adsorption kinetics was in agreement with the Elovich equation, and all equilibrium isotherms were in agreement with the Langmuir equation. These results were used to compare the Elovich parameter (1/b) and the adsorption quantity of the unit area (q(mon)/Sp) of activated carbons with different CO2 gasification durations. This work facilitated the preparation of activated carbon by effectively controlling pore structures and the adsorption performance of the activated carbon on adsorbates of different molecular forms.     

ESTIMATION OF ACTIVATED ENERGY OF DESORPTION OF n-HEXANE ON ACTIVATED CARBONS BY TPD TECHNIQUE

1. INTRODUCTION In some cities of China, cancer and breath system diseases caused by the pollution of volatile organic compounds (VOCs) have been obviously increasing. The VOCs includes BTEX (benzene, toluene, ethylbenzene, and xylene), aldehydes, cresol, phenol, acetic acid, polynuclear aromatic hydrocarbons (PAHs), which have long-term human health implications. Emission of the VOCs has threatened the health of people seriously [1,2]. The pollution of the VOCs mostly hails from…