生物质莲杆废弃物制备高比表面积多孔炭及其CO_2吸附性能（英文）

采用水热炭化和KOH活化相结合的方法,以生物质莲杆废弃物为碳源,制备了高比表面积多孔炭材料,并探索其CO_2吸附性能。分别采用氮气物理吸附、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和元素分析技术(XPS)对这种莲杆基多孔炭材料的孔道结构、形貌和表面化学等特性进行了研究。结果表明,KOH浓度对莲杆基多孔炭材料的孔结构具有较大影响,莲杆基多孔炭材料的比表面积和孔体积分别为2 893 m~2/g和1.59 cm~3/g,KOH活化处理能在增大多孔炭材料的比表面积和孔体积,同时会在其内部形成部分具有较大尺寸的微孔和较小尺寸的介孔结构。在常压条件下,CO_2的吸附测试表明莲杆基多孔炭材料在25℃和0℃时的吸附量分别高达3.85和6.17 mmol/g,这一吸附量在生物质基多孔炭材料中属于较高水平。然而,具有最高比表面积的莲杆基多孔炭材料(AC-4样品)并不具备最高的CO_2吸附量,这意味着常压条件下限制CO_2吸附量的决定性因素并不是比表面积,而主要由微孔率和孔径分布决定。这一研究结果为设计多孔吸附剂应用于CO_2捕集方面提供了重要意义,也为构建低成本且环境友好的具有高吸附量的CO_2吸附剂提供思路。     

锂离子电池用CoMoO_4/炭颗粒与氮掺杂多孔炭复合材料（英文）

超精细过渡金属氧化物(TMO)在储锂方面具有巨大潜力,但在实际应用中还存在易团聚、电导率低等挑战。本文采用双炭复合方法,首先将ZIFs-67固定于模板法制备的石油沥青基多孔炭骨架上,然后将配位Co~(2+)原位转化为CoMoO_4@炭纳米颗粒,生成CoMoO_4@炭纳米颗粒/多孔炭骨架(CoMoO_4@CP/CF)。通过ZIFs-67热解制备出N掺杂炭骨架,从本质上提高CoMoO_4电子传输能力,而超细炭纳米颗粒可以有效阻止CoMoO_4聚集。基于上述优点,将该复合材料用做锂离子电池负极,电流密度为1 A g~(-1)时,可提供高达818 mAh g~(-1)的可逆比容量。该合成方法为高性能储能电极材料的设计提供了新途径。     

用作气相催化反应体系CNF/泡沫炭催化剂载体的合成

以中间相沥青为碳质前躯体,采用自发泡法制得泡沫炭.为了提高比表面积,泡沫炭经质量分数65％的HNO3氧化后,采用化学气相沉积法在其表面生长一层纳米炭纤维(CNFs).泡沫炭表面生长一层CNFs后,其比表面积和导热系数分别由40m2/g、107W/mK相应提高到198 m2/g、125W/mK.这种结构的CNFs/泡沫炭复合材料可以用作气相催化反应体系的催化剂载体.     

多级孔炭电极材料的制备及其性能研究

以聚醚F127、间苯三酚和甲醛为原料,采用KOH活化法制备出具有介孔、微孔的多级孔炭材料,利用BET、XRD、SEM对样品的组成和结构进行了表征.结果表明:随着升温速率的增加和炭化时间的减少,介孔炭材料的比表面积、孔容以及介孔表面积先增大后减小.10℃/min条件下可获得最优性能的介孔炭,其介孔表面积为324.47m2...     

硝酸镍在模板法制备中孔炭中的作用

以热固性酚醛树脂(Thermosetting phenol resin,TPR)为炭前驱体,纳米SiO2为模板、硝酸镍为添加剂制备中孔炭(Mesoporous carbons,MCs).借助比表面积测定仪和X-射线衍射分析仪,研究了添加剂加入前后中孔炭孔结构和微晶结构的变化.结果表明:加入适当含量的硝酸镍可提高中孔炭的比表面积,同时增加炭的石墨化度;通过调节硝酸镍的含量,可以制备具有孔径分布集中在4nm和10nm左右的双峰分布的中孔炭.     

高比表面椰壳活性炭和纳米级Pd/C催化剂的制备与表征

以海南椰壳为原料,粉碎、过筛后,采用二步活化法制备活性炭.先500℃下碳化,然后以KOH为活化剂,炭碱质量比1∶2、1∶3、1∶4,炉温分别为700℃、800℃和900℃在氮气保护下活化.在炭碱比1∶4,活化温度800℃时,得到的活性炭比表面积高达3275m2/g.将得到的比表面积在1100～3200m2/g活性炭通过PdCl2超声浸渍法,水合肼还原制备纳米级钯炭催化剂,经SA、XRD、TEM等分析,得出比表面积越大,纳米钯粒子在活性炭上的分布越均匀,粒子颗粒越小.     

染料敏化太阳电池多级孔炭对电极的制备及性能研究

以F127为模板剂, 采用自组装与后活化相结合制备了具有微孔-介孔结构的多级孔炭. N2吸附等温线分析表明后活化可在介孔炭孔壁上生成大量微孔. 电化学阻抗谱测量表明多级孔炭电极对I₃^-还原反应的催化活性明显高于介孔炭电极, 电荷迁跃电阻为0.3 Ω·cm². 多级孔炭电极催化活性高是由于它具有较高的比表面和特殊的多级孔结构, 有效比表面积较高. 以多级孔炭电极为对电极组装染料敏化太阳电池, 电池的短路电流密度、开路电压和填充因子分别为0.624V、15.44 mA/cm²和0.67, 相应的光电转换效率为6.48%, 比介孔炭对电极电池的光电转换效率提高了11.5%.     

煤焦油合成氮掺杂中孔炭纳米片及其储锂性能(英文)

以煤焦油为碳源,三聚氰胺为氮源,MgO纳米片为模板,通过预氧化和炭化过程合成出氮掺杂中孔炭纳米片(NMCNs),可实现对中孔炭材料的孔结构和氮掺杂含量的调控。所制中孔炭材料具有独特的中孔和片状结构,比表面积较大(1209m2/g),氮掺杂量较高(8.6%)。将其应用于锂离子电池负极材料,NMCNs展现出比容量高和循环稳定性优良的特性,在电流密度为100mA/g时具有高达1 000mAh/g的比容量。     

一步模板炭化法制备新型沥青基中孔炭材料

以乙酸镁和柠檬酸镁为模板(MgO)镁源,沥青为碳前驱体,在氮气氛中950℃一步炭化制得高表面积中孔炭材料.采用1 mol/L的HCl去模,并将炭材料洗涤至中性.采用低温N2吸附测得炭材料的比表面积和孔径分布,透射电镜观察炭材料的内部结构特征.结果表明:尽管未经活化,所得炭材料中的孔大多为中孔,BET比表而积达到1295 m2/g,当以柠檬酸镁为MgO前驱体时,所得炭材料的收率可高达50%.     

三种碳源对CNF/AC复合材料性能的影响

采用甲烷、正丁烷、乙炔3种烃类气体作为碳源,纳米金属镍为催化剂,在活性炭(AC)上生长了纳米碳纤维(CNF)。通过氮气等温吸附、粉末比电阻、扫描电镜(SEM)和X光衍射(XRD)等一系列表征手段,比较了3种碳源对获得的CNF/AC复合材料的比表面积、导电性,以及其中的CNF形貌的影响。结果表明,在相同生长条件下,碳沉积速度与碳源气的碳氢比成正相关,与产物的比表面积成负相关。提出碳源气在化学气相沉积(CVD)过程对产物性能影响的机理,提出依据分子中碳气原子比选择烃类碳源气,从而提高CVD过程催化分解反应选择性的方法。     

Fabrication of 3D carbon nanotube/porous carbon hybrid materials

Three dimensional hybrid carbon materials have been prepared using different biomass-derived porous carbons as catalyst supports for growing multi-walled carbon nanotubes (MWCNTs) via a chemical vapor deposition method. The nickel catalyst-loaded supports before and after growing MWCNTs were characterized by scanning and transmission electron microscopy, Fourier transform infrared spectroscopy spectra, and mercury porosimetry. The results show that the grown MWCNTs microstructures are closely related to the porous structures and surface conditions of the carbon supports. By using bamboo as template, a porous carbon support with a large total pore volume, appropriate pore size, and abundant favorable surface functional groups is obtained, which is found to be an ideal support for growing the MWCNTs. Investigation of growth mechanism demonstrated that the combination of appropriate porous structures and surface conditions plays an essential role in catalyst distribution and MWCNTs growth.     

以石油渣油为原料制备多孔炭

以石油渣油为原料,分别采取传统的水蒸气活化和类模板法制备多孔炭材料,并采用氮吸附、XRD和SEM等分析手段对得到的多孔炭进行了表征。结果表明,水蒸气活化制备的多孔炭以微孔为主,且随着活化时间的增加,比表面积增大,炭收率减小。而类模板法制备的多孔炭以中孔为主,且随着MgO/渣油配比值的增加,其比表面积随之增大,炭收率变化不大。     

Performance of electrical double layer capacitors with porous carbons derived from rice husk

The porous structure and electrochemical double layer capacitance of porous carbons prepared from rice husks by using alkali hydroxide as activating agents were investigated. Three samples of carbons prepared by NaOH-activation, three samples prepared by KOH-activation and two samples of commercial carbons have been studied. The porosity of the carbons was characterized by nitrogen adsorption isotherms at 77 K and electrochemical constant current cycling method was used to measure the double layer capacitance. The specific capacitance of the carbons is not linearly proportional to the surface area. Additionally, the double layer capacitance strongly depends on the pore structure and the functional groups. A specific capacitance larger than 200 F g⁻¹ was achieved by using the porous carbon prepared with NaOH (activation temperature: 750 °C; activation time: 30 min). All the carbons prepared with rice husk in this study have larger double layer capacitance (125–210 F g⁻¹) than the commercial grade carbons (78–100 F g⁻¹).     

氢氧化钾活化制备可再生多孔碳及其电催化氧还原性能研究

氧还原反应缓慢的动力学过程严重限制了燃料电池的能量转换效率, 而商用Pt/C催化剂成本太高、资源稀缺、稳定性差, 需要寻找合适的材料来取代商用的Pt/C催化剂。近年来, 氮掺杂多孔碳材料因其独特的物理和化学特性吸引了大量的关注。本文使用富含氮元素的可再生土豆作为生物质前驱体, 通过简单的一步热解过程和KOH活化方法相结合制备出了一系列氮掺杂多孔碳电催化剂; 并系统研究了KOH用量和活化温度对碳基体孔结构和电催化性能的影响。结果表明, 当活化温度为750 ℃、KOH与碳的质量比为3/1时, 所制备的催化剂(NPC-750)的氧还原活性最高, 起始电位和半波电位分别达到0.89和0.79 V (vs. RHE), 极限电流密度达到5.53 mA?cm ^-2。NPC-750优异的氧还原催化活性主要归因于其发达的孔结构、高的比表面积(1134.2 m ²?g ^-1)和合适的氮含量(1.57at%)。同时, 优异的循环稳定性和抗甲醇中毒性能进一步说明这些生物多孔碳材料是潜在的低成本氧还原电催化剂。此外, 这些高比表面积多孔碳在超级电容、吸附/分离、催化以及电池等领域也具有潜在的应用前景。     

Study on preparation of activated mesocarbon microbeads/expanded graphite composites for electrical double layer capacitors

Electrical double-layer capacitors are now developing very fast and people put their eyes on the investigation about materials for electrodes, such as activated carbon with high surface area. One of the main ways to enhance the capacitance of porous carbonaceous materials was to improve the porosity and specific surface area. In this paper, a novel preparation process to increase the capacitance of activated carbon without changing pore structure was discussed and expanded graphite, which was usually used in the polymer material system, was used as the composite template for activated carbons. Expanded graphite with worm-like and symmetrical pores could provide good environment for activated carbon particles to touch with each other and the structure defects at the contacting sites were offset at a certain extent. The adsorption properties of activated carbons had not been changed much more after composite preparation but the capacitance of each composite had been improved greatly because that activated carbon particles were surrounded by plenty of graphite layers with better electrical conductivities. As a result, electrical double-layer capacitors made with composites had higher capacitance comparing with activate carbons themselves and had good performance under larger discharging currents.     

印刻法制备中间相沥青基中孔炭

用中间相沥青作碳源,硅胶水溶液作造孔剂,采用胶体印刻法制得一系列中孔碳。实验发现当适量纳米级硅源添加到中间相沥青中,会在彼此颗粒间形成一定的纳米孔道,从而导致中间相沥青在炭化过程中没有沥青由固相向液相转化的过程。结果表明：碳硅比、印刻温度以及中间相沥青的基本物化性质都将对中孔碳的孔结构发生重要影响。且制得比表面积和孔容分别为482m2/g和1.62cm3/g的中孔碳。     

竹基活性炭在水性和有机电解液中的电容特性

以高比表面积竹质活性炭作为双电层电容器的电极材料,采用恒流充放电、等效串联电阻、漏电流等方法分别测试了其在水性电解液和有机电解液中的电化学性能。结果表明,高比表面积竹基活性炭具有优异的能量储存特性、稳定的电化学特性和脉冲性能,在水性电解液中展示出优异的高频耦合特性,在水性和有机电解液中的比电容值分别为206F/g和133F/g。根据双膜态孔径分布理论可知,较大孔径的孔既可被水性电解液浸润也可被有机电解液浸润,较小孔径的孔则只能被水性电解液浸润。     

NaY分子筛模板法合成多孔炭材料

采用NaY沸石分子筛作模板,乙酰丙酮为炭前驱体,使用液相浸渍-气相沉积工艺合成了富含微孔和中孔结构的多孔炭材料并对其进行了表征.所合成的多孔炭比表面积1351m2/g,孔容0.892cm3/g,微孔率0.63,孔径分布多在0.8nm～3.0nm之间.     

Adsorption of naphthalene from aqueous solution on activated carbons obtained from bean pods

The preparation of activated carbons from bean pods waste by chemical (K(2)CO(3)) and physical (water vapor) activation was investigated. The carbon prepared by chemical activation presented a more developed porous structure (surface area 1580 m(2) g(-1) and pore volume 0.809 cm(3) g(-1)) than the one obtained by water vapor activation (258 m(2) g(-1) and 0.206 cm(3) g(-1)). These carbons were explored as adsorbents for the adsorption of naphthalene from water solutions at low concentration and room temperature and their properties are compared with those of commercial activated carbons. Naphthalene adsorption on the carbons obtained from agricultural waste was stronger than that of carbon adsorbents reported in the literature. This seems to be due to the presence of large amounts of basic groups on the bean-pod-based carbons. The adsorption capacity evaluated from Freundlich equation was found to depend on both the textural and chemical properties of the carbons. Naphthalene uptake on biomass-derived carbons was 300 and 85 mg g(-1) for the carbon prepared by chemical and physical activation, respectively. Moreover, when the uptake is normalized per unit area of adsorbent, the least porous carbon displays enhanced naphthalene removal. The results suggest an important role of the carbon composition including mineral matter in naphthalene retention. This issue remains under investigation.     

Porous carbons

Carbon in dense as well as porous solid form is used in a variety of applications. Activated porous carbons are made through pyrolysis and activation of carbonaceous natural as well as synthetic precursors. Pyrolysed woods replicate the structure of original wood but as such possess very low surface areas and poor adsorption capacities. On activation, these exhibit increased adsorption volumes of 0.5-0.8 cm³/gm and surface areas of 700–1800 m²/gm depending on activation conditions, whether physical or chemical. Former carbons possess mixed pore size distribution while chemically activated carbons predominantly possess micropores. Thus, these carbons can be used for adsorption of wide distributions of molecules from gas to liquid. The molecular adsorption within the pores is due to single layer or multilayer molecule deposition at the pore walls and hence results in different types of adsorption isotherm. On the other hand, activated carbon fibres with controlled microporous structure and surface area in the range of 2500 m²/gm can be developed by controlled pyrolysis and physical activation of amorphous carbon fibres. Active carbon fibres with unmatchable pore structure and surface characteristics are present and futuristic porous materials for a number of applications from pollution control to energy storage.