水热炭化法制备生物质基碳纳米材料研究进展

碳纳米材料因具有良好的吸附、电化学、催化以及气体贮存性能,被认为是材料科学研究中的热点明星.碳纳米材料大致分为富勒烯、碳纳米管、石墨烯、碳微球、碳纳米杂化材料等.碳纳米材料的研究重点是探索简易、环保、低能耗、过程可控的制备方法.现在主要的研究手段是利用可再生的木质纤维原料衍生物、纤维素、半纤维以及构成这些聚糖的结构单糖等碳水化合物作为碳源,进行水热炭化反应.本文详细介绍了生物质水热炭化过程中所发生的降解及炭化反应,着重介绍了水热炭化制备生物质碳微球以及生物质碳包覆纳米颗粒过程中涉及的成核生长机理.在此基础上,还分别论述了碳微球、碳包覆纳米复合材料的合成工艺.同时对上述碳纳米材料在水污染治理、电化学、催化、生物及传感器领域等方面进行了全面的概括.最后,本文总结了前人研究工作中存在的几点问题并提出了相应的建议.     

水热碳化法制备碳微球

以糖类为原料,采用水热法制备碳微球,研究不同反应物以及反应条件对水热碳的影响。利用X射线衍射(XRD)和扫描电子显微镜(SEM)对产物碳微球的结构和形貌进行表征,并借助傅立叶红外(FTIR)和X射线光电子能谱(XPS)探讨了糖类水热碳化的反应机理。     

麦秸秆为原料新绿色工艺制备碳微球

以麦秸秆粉末为原料,先将麦秸秆粉末与水的混合液于190℃的干燥箱中无催化剂条件下水解1h,然后以水解后的清液为碳源于180℃下无催化剂条件下水热碳化8h来制备碳纳米材料,探讨了秸秆粉末与水的固液比对产物形貌的影响。通过红外光谱仪对产物的表面官能团进行了分析,通过扫描电子显微镜对产物的微观形貌进行表征。结果显示:所制备的产物为带有大量O—H基、CHO基等官能团的碳微球,固液比对碳微球的粒径有较大的影响,固液比为1∶60时产物为外壁光滑的碳微球,其粒径在100~300nm之间;固液比为1∶40时,所制备碳微球,粒径较大,多数直径在250nm左右;固液比为1∶20时产物中明显有直径约800nm左右的大球出现,大直径的碳微球球壁看起来较光滑,但产物的均匀性变差。     

水热氧化还原法制备聚乙烯醇碳微球EI北大核心CSCD

以六水合三氯化铁和聚乙烯醇(PVA)为原料,通过水热条件下氧化还原反应成功制备了功能化的聚乙烯醇碳微球(CMS)。三价铁离子具有氧化性,而聚乙烯醇分子链上的羟基具有还原性,混合溶液中Fe3+在聚乙烯醇羟基的作用下被还原为Fe2+,聚乙烯醇则在水热条件下被氧化,聚乙烯醇的晶体结构被破坏。通过X射线衍射、红外光谱等方法对聚乙烯醇在水热环境下所得碳微球的结构特征进行了分析。结果表明,碳微球的表面含有大量羟基、羧基等活性含氧官能团,并且可以在水或无水乙醇中良好分散。     

重油残渣基新型碳功能材料的研究进展

综述了以重油残渣为原料,采用化学气相沉积法、共炭化法和微波等离子体法可控制备气相生长碳纤维、碳微球、内包铁洋葱状富勒烯、纳米碳管、内包金属碳微米颗粒及定向碳纳米薄膜等各种高附加值碳材料;采用等离子体氧化法、酸处理法、化学还原法等方法对气相生长碳纤维和碳微球进行表面修饰,在产物表面引入含氧官能团,解决了可溶性碳材料的制备问题;在碳微球表面引入Pt纳米颗粒,使重油残渣基新型碳材料在表面修饰和功能化后可望成为性能优异的吸附和催化材料.     

SnO2空心壳球材料及其碳包覆物的制备与性能表征

采用水热合成法以SiO2微球为模板制备了SnO2空心壳球材料，并对其进行了碳包覆改性。采用XRD和SEM表征了所得材料的结构和表面形貌，并进一步研究了所得材料作为锂离子电池电极材料的电化学性能。XRD和SEM结果表明，所制备的SnO2空心壳球材料为四方相金红石结构，不合其它杂质，呈不规则壳球状形貌，经过碳包覆后呈规则球...     

纤维素制备碳材料的工艺与机理研究

以纤维素作原料,利用水热碳化法,在一定的温度和压强下制备碳纳米材料。通过单因素实验考察了反应温度、反应时间对产物表观形貌的影响。采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)及红外光谱仪(FT-IR)对所得碳材料的微观形貌和表面生成的官能团进行表征与测试。结果表明:纤维素水热碳化的起始温度为230℃,290℃为最佳碳化温度;当T=290℃时,反应时间的延长可增大碳颗粒的球化趋势,而对粒径影响较小;经水热碳化制备的碳材料表面含有羟基、羰基和羧基等官能团。     

胶体碳微球的活化及其亚甲基蓝液相吸附性能的研究

以葡萄糖为前驱体,采用液相碳化法,制备颗粒约为100～200nm胶体碳微球.采用KOH作活化剂对胶体碳微球进行活化处理.考察了碱炭比、活化温度和保温时间等工艺因素对孔径和比表面积的影响.通过XRD、SEM等分析手段对胶体碳微球活化前后的表面形貌、孔径分布、显微结构进行分析.经热处理和活化后,胶体碳微球的BET比表面积从26.6m2/g增加到1383.4m2/g.相同实验条件下,在亚甲基蓝液相吸附试验中,经活化处理后的样品所表现出的吸附量是商业活性炭Calgon-F300的两倍.     

低密度碳空心微球的制备及酚醛树脂空心微球复合材料的性能

以BJO-0930酚醛树脂空心微球为原料,通过酸洗、预氧化、碳化三步工艺,成功制备球形度好、强度高的碳空心微球,并与热固性酚醛树脂复合,热压成型得到轻质酚醛树脂/空心微球复合材料。系统考察了碳化温度、循环酸洗、预氧化等对碳空心微球强度的影响。复合材料的力学性能和隔热性能分别通过压缩性能以及热导率测试进行表征。结果表明:直接碳化得到的碳空心微球破球率高、强度低;通过循环酸洗可以有效去除树脂球的灰分,破球率由28.07%降低至18.03%;进一步预氧化处理可以显著提高碳空心微球的强度,其破球率和等静压破球率分别为10.03%和17.34%;制备得到的酚醛树脂/碳空心微球复合材料具有优异的隔热性能和力学性能,热导率降低至0.115 W·m~(-1)·K~(-1),压缩强度为46.02MPa。     

直接水热合成法和模板剂法制备碳微球的比较及性能评价

以葡萄糖为碳源,分别采用直接水热合成法和模板剂法制备了碳微球并将其制备成催化剂。利用扫描电镜和傅里叶变换红外光谱仪等手段对碳微球及催化剂进行表征。评价了催化剂在纤维素水解反应中的催化活性。结果表明:两种方法制备的碳微球粒径相差较大,结构上都含有—OH和—COOH官能团;两种方法制备的催化剂粒径有很大差别而且球之间粘连较严重,两者均含有—SO3H、—COOH、—OH等活性基团。并且模板剂法制备的碳微球催化剂对纤维素的水解率较高,达到58%。     

炭微球制备技术的研究动态

综述了近年来炭微球制备技术的研究动态,重点阐述了几种广泛采用的制备炭微球的方法及其优缺点,并指出研制成本低、工艺简单、产品粒径小的技术是今后炭微球制备技术的发展方向.     

Tailoring Polymer Colloids Derived Porous Carbon Spheres Based on Specific Chemical Reactions

Porous carbon spheres derived from polymer colloids with regular geometry, monodispersed morphology, well-controlled contents and structures play important roles in many areas of application, such as energy storage/conversion, gas adsorption/separation, catalysis, and chemo-photothermal therapy. Suitable polymerization reaction and synthetic strategy are both critical for the obtainment of stable polymer colloids as carbon precursors. Basic polymerization reactions are the cornerstones of synthetic strategies, which directly provides the direct molecular-based design of functionalized polymer/carbon spheres. Thus, this progress report mainly focuses on the summary of suitable polymerization reactions for colloidal polymer derived porous carbon spheres. Recent advances in the synthetic strategies and applications are also discussed, including their corresponding polymerization reactions. Finally, the perspectives for the development of polymer derived porous carbon spheres are provided based on the controlled synthesis of polymer colloids and optimization over the carbonization process to achieve highly functionalized carbon spheres for practical applications.     

聚合物共混炭化法制备多孔炭材料的研究进展

聚合物共混炭化法有望成为一种能够对炭材料孔径进行精细控制的方法。该方法利用两种热稳定性不同、可形成相分离结构的聚合物共混炭化，热稳定性高的聚合物经过高温炭化成为炭基体，热稳定性差的聚合物则在热处理过程中分解气化，并在炭化产物中留下孔隙结构。综述了聚合物共混炭化法制备多孔炭材料的原理、方法、研究现状及最新进展，并指出共混聚合物分相相畴的控制和炭化过程中孔结构的控制是该法所存在的主要问题。     

Nano-structural investigations of porous silica coated carbonaceous spheres and dielectric properties of its organosilicone hybrid film

In this research, a series of carbonaceous spheres samples were synthesized by hydrothermal carbonization of glucose and cyclodextrin, and coated with mesoporous silica. The unique nano-structure of such carbonaceous spheres samples was fully characterized by DLS, XRD, SEM, TEM, Raman spectroscopy and infrared spectroscopy techniques. Such carbonaceous spheres samples were then blended with organosilicone in order to prepare a series of hybrid films. The influence of the added silica coated carbonaceous spheres on the dielectric property of these hybrid film samples was thoroughly investigated. The results indicate that the silica coated carbonaceous spheres are amorphous and have a typical core-shell structure. Such nano-structure and aggregation behavior in the organosilicone matrix can introduce more interfaces into the hybrid organosilicon film samples, and have notably affected the dielectric property of the hybrid organosilicon film samples. The dielectric constant and dielectric loss of the hybrid film samples could be kept relatively low if the introduced interfaces were blurred enough to avoid the interfacial polarity.     

A novel method for preparation of hollow and solid carbon spheres

Hollow and solid carbon spheres were prepared by the reaction of ferrocene and ammonium carbonate in a sealed quartz tube at 500°C. The morphology and microstructure of the product were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The carbon spheres are amorphous and their diameters range from 0·8–2·8 μm. The shell thickness of the hollow carbon spheres is not uniform and ranges from 100–180 nm. It is suggested that ammonium carbonate is crucial for the formation of carbon spheres and its amount also influences the morphology of the product. The method may be suitable for large scale preparation of carbon spheres.     

Bi_2MoO_6空心球的水热沉淀法制备及其光催化性能

以葡萄糖为前躯体,采用水热法制备胶体碳球,以其为模板通过水热沉淀法制备C/Bi2MoO6核壳结构,然后在350℃空气中煅烧,获得了具有良好光催化性能的Bi2MoO6空心球.通过SEM、XRD、FT-IR和BET等测试方法对该催化剂进行了表征;并对其形成机理及反应过程进行了初步探讨,以亚甲基蓝作为被降解物质,研究了其光催化活性。结果表明,Bi2MoO6空心球是由纳米晶粒组成的,壁厚约为30～50nm,平均直径约为0.6～0.8μm,采用胶体碳球作模板时制得的Bi2MoO6空心球比表面积为11.315m2/g,而直接合成的粉体比表面积为3.378m2/g。在黑管灯照射下,2.5h亚甲基蓝的降解率达到了91.95%。     

Nanoengineering Carbon Spheres as Nanoreactors for Sustainable Energy Applications

Colloidal carbon sphere nanoreactors have been explored extensively as a class of versatile materials for various applications in energy storage, electrochemical conversion, and catalysis, due to their unique properties such as excellent electrical conductivity, high specific surface area, controlled porosity and permeability, and surface functionality. Here, the latest updated research on colloidal carbon sphere nanoreactor, in terms of both their synthesis and applications, is summarized. Various synthetic strategies are first discussed, including the hard template method, the soft template method, hydrothermal carbonization, the microemulsion polymerization method, and extension of the Stöber method. Then, the functionalization of colloidal carbon sphere nanoreactors, including the nanoengineering of compositions and the surface features, is discussed. Afterward, recent progress in the major applications of colloidal carbon sphere nanoreactors, in the areas of energy storage, electrochemical conversion, and catalysis, is presented. Finally, the perspectives and challenges for future developments are discussed in terms of controlled synthesis and functionalization of the colloidal carbon sphere nanoreactors with tunable structure, and the composition and properties that are desirable for practical applications.     

碳/掺杂碳气凝胶及其研究进展

经溶胶-凝胶、超临界干燥和高温碳化过程制备的碳气凝胶及通过掺杂获得的掺杂碳气凝胶是一种新型的轻质纳米多孔材料,具有许多优异的性能和广阔的应用前景.介绍了溶胶-凝胶法的反应机理,综述了碳/掺杂碳气凝胶的制备方法、发展现状,指出了目前存在的问题并提出了新的可行的制备掺杂碳气凝胶的方法.     

球形活性炭及其应用

球形活性炭外表为均匀，光滑的球形，在固定床使用时填充密度均匀，对气体或液体的流体阻力小，所以近年来作为口服吸附剂以及血液灌流器中的吸附剂得到了广泛的应用，与活性炭纤维，粒状活动炭相比，球形活性炭的研究与报道较少，对现有几种球形活性炭的特点，应用现状以及今后的发展方向进行了综述。     

A facile preparation of pomegranate-like porous carbon by carbonization and activation of phenolic resin prepared via hydrothermal synthesis in KOH solution for high performance supercapacitor electrodes

High electrochemical performance pomegranate-like porous carbon was synthesized by the carbonization and activation of phenolic resin which was prepared by adding phenolic resin monomer mixture into KOH aqueous solution and hydrothermal treatment. In the process of hydrothermal, KOH solution could hinder the polymerization of phenolic resin monomer to form big phenolic resin particles. During the carbonization, phenolic resin plays the role of forming small particles and binder during carbonization, which can simultaneously achieve high specific surface area and form three dimensional structures to improve the conductivity. The results showed that pomegranate-like porous carbon composed of small nanometer-scale particles was observed. The obtained porous carbon electrode materials had a high content of micropores with specific surface area as high as 2199.9 m² g⁻¹. The porous carbon exhibited a high specific capacitance of 341.3 F g⁻¹ at 0.1 A g⁻¹, good rate capability with 71.0% retention from 0.1 to 5 A g⁻¹. Moreover, it showed high capacitance retention of 96.1% after 5000 cycles at a scan rate of 50 mV s⁻¹, indicating excellent cycling stability. The assembled symmetrical supercapacitor showed high energy densities of 17.0 Wh kg⁻¹ and 8.5 Wh kg⁻¹ with the corresponding power densities of 49.6 W kg⁻¹ and 1.8 kW kg⁻¹, respectively. The facile method could be a promising candidate for preparing porous carbon electrode materials with excellent electrochemical performance in the fields of supercapacitors.