High effects of smoke suppression and char formation of Ni?Mo/Mg(OH)2 for polypropylene

The Ni? Mo/Mg(OH)₂ (NMM) hybrid as an efficient flame retardancy and smoke suppression composite for polypropylene (PP) was synthesized through Ni? Mo co‐precipitation on the surface of Mg(OH)₂ (MH) hexagonal nanosheets. Compared to PP/MH, PP/NMM exhibited excellent smoke suppressing and flame retardancy on the heat release rate, total heat release, smoke production rate, total smoke production, CO production rate and total CO production with the same loading. The reduced hazard of PP/NMM was mainly attributed to the high physical barrier effect of compact char residues on heat, smoke and combustible gas. The mechanism study indicated that multiwalled carbon nanotubes (MWCNTs) generated from the catalytic carbonization of PP by the Ni? Mo compound could play the role of “rebar” to strengthen the char residues, avoid the generation of cracks and form highly compact char layer. Furthermore, MgO could facilitate the production of MWCNTs through changing the pyrolysis process of PP and increasing the reaction time between pyrolysis gas and Ni? Mo compound. Hence, the new Ni? Mo/MH catalyst hybrid may explore the potential for solving the tough problem of the flammability and heavy smoke of the polyolefins system.     

High performance carbon–carbon composites obtained by a two-step process from phthalonitrile matrix composites

Carbon–carbon composites (C/C) were produced from carbon fiber reinforced phthalonitrile (CFRP) matrix composites in a two-step impregnation–carbonization procedure. After graphitization at 1800 °C, the obtained C/C composites demonstrated highly crystalline structure and properties characteristic of composites derived from phenolic matrix CFRP by the industrial procedure: d = 1.73 g cm^?3, interlaminar shear strength was 14.1 MPa, compression strength was 139.8 MPa, and coefficient of friction was in the range 0.32–0.34.     

Facial Synthesis of Adsorbent from Hemicelluloses for Cr(VI) Adsorption

It is challenging work to develop a low-cost, efficient, and environmentally friendly Cr(VI) adsorbent for waste water treatment. In this paper, we used hemicelluloses from chemical fiber factory waste as the raw material, and prepared two kinds of carbon materials by the green hydrothermal method as adsorbent for Cr(VI). The results showed that hemicelluloses hydrothermally treated with citric acid (HTC) presented spherical shapes, and hemicelluloses hydrothermally treated with ammonia solution (HTC-NH₂) provided spongy structures. The adsorption capacity of the samples can be obtained by the Langmuir model, and the adsorption kinetics could be described by the pseudo-second-order model at pH 1.0. The maximum adsorption capacity of HTC-NH₂ in the Langmuir model is 74.60 mg/g, much higher than that of HTC (61.25 mg/g). The green hydrothermal treatment of biomass with ammonia solution will provide a simple and feasible way to prepare adsorbent for Cr(VI) in waste water treatment.     

Fabrication of sulfonated mesoporous carbon by evaporation induced self-assembly/carbonization approach and its supercapacitive properties

Synthesis of functionalized mesoporous carbon by an easy-accessed method is of great importance towards its practical applications.Herein,an evaporation induced self-assembly/carbonization(EISAC) method was developed and applied to the synthesis of sulfonic acid group functionalized mesoporous carbon(SMC).The final mesoporous carbon obtained by EISAC method possesses wormlike mesoporous structure,uniform pore size(3.6 nm),large surface area of 735 m²/g,graphitic pore walls and rich sulfonic acid group.Moreover,the resultant mesoporous carbon achieves a superior electrochemical capacitive performances(216 F/g)to phenolic resin derived mesoporous carbon(OMC,152 F/g)and commercial activated carbon(AC,119 F/g).     

表面活性剂碳化法合成Fe3O4/C复合物及其电化学性能

以水热法合成的包覆油酸的α-Fe₂O₃粒子为前驱体, 在氩气下500 °C煅烧1 h, 得到Fe₃O₄/C纳米复合物. 用傅里叶变换红外(FTIR)光谱, X射线衍射(XRD), 扫描电镜(SEM), X射线能量散射(EDX)谱, 高分辨透射电镜(HRTEM), 元素分析, 循环伏安(CV)和恒流充放电测试等方法对材料的结构、形貌、成分及电化学性能进行了表征. 结果表明: 所制备的Fe₃O₄/C复合物呈长约200 nm, 粗约100 nm的纺锤形, 表面碳层厚约1-2 nm, 碳含量为1.956%(质量分数); 这种复合物作为锂离子电池负极材料具有很好的循环稳定性(在0.2C (1C=928 mA·g^-1)循环80次后具有691.7 mAh·g^-1比容量)和倍率性能(在2C循环20次后依然有520 mAh·g^-1比容量). 相对于未包覆的商业Fe₃O₄粒子, 复合物显著提高的电化学性能是由于碳包覆能防止粒子聚集, 提高导电性以及稳定固体电解质界面(SEI)膜.     

香菇生物质基氮掺杂微孔碳材料的制备及其在超级电容器中的应用

采用简易浸泡法和一步碳化/活化法制备香菇生物质基氮掺杂微孔碳材料(NMCs),利用扫描电子显微镜(SEM)、透射电子显微镜(SEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)对材料的结构形貌进行表征,并研究了其超级电容特性。测试结果表明,NMCs的微孔比表面积高达1 594 m~2·g~(-1),且拥有更高数量的含氮官能团,其吡啶型含氮官能团比例也有所提高,展现出优异的超级电容特性。在0.5 A·g~(-1)的电流密度下,其比容量高达325 F·g~(-1),当电流密度上升到20 A·g~(-1)时,其比电容仍然高达180 F·g~(-1),表现出优异的倍率性能;同时,在5 A·g~(-1)的电流密度下,电极经历5 000次充放电循环后具有97.7%的比容量保持率,展现出优异的循环稳定性。这主要归因于NMCs超高的微孔比表面积和丰富的含氮官能团。     

Hydrothermal preparation of hybrid carbon/silica monolithic capillary column for liquid chromatography

A simple, easy and economical approach for the preparation of a hybrid carbon/silica monolithic capillary column was described for the first time by using silica monolith as framework in combination with hydrothermal carbonization at 180°C. During the preparation process, formamide was introduced to the reaction solutions to reduce the dissolution rate of monolithic silica skeleton and its optimal concentration was 1.5 M. Fourier transform infrared spectrometry, scanning electron microscopy, energy dispersive X‐ray spectrometry, and inverse size exclusion chromatography were carried out to characterize the as‐prepared column. The results demonstrated that carbon spheres ranging from 150 to 1000 nm were successfully attached to the surface of silica skeleton. The prepared hybrid carbon/silica column had a permeability of 4.4 × 10^?14 m². Chromatographic performance of the column was evaluated by separation of various compounds including alkylbenzenes, nucleosides and bases, and aromatic acids. The column exhibited an efficiency of 75 000 plates/m for butylbenzene at the optimal linear velocity of 0.23 mm/s. The successful separation of these compounds and the study on mechanism indicated that the column can be applied in mixed‐mode chromatography.     

碱性膜燃料电池阳极碳酸化模型研究

碱性聚电解质燃料电池（APEFC）近年来取得了可观的进展,但是在使用空气作为氧化剂工作时仍然面临着性能损失. 文献中已有多个理论试图解释性能损失的来源,但是缺乏定量化的分析. 本文根据实验发现和热力学及阳极反应的动力学分析,提出了分层的阳极碳酸化模型和方程组.模型的定量化模拟结果进一步和实验结果进行验证,提出了电池性能损失的可能原因.     

催化反应制备碳化硅纳米粉体的密度泛函理论计算及实验研究

以Si_(55),Si_(43)M_(12)和Si_(37)M_(18)(M=Fe,Co或Ni)团簇为模型,采用密度泛函理论(DFT)研究了Fe,Co及Ni纳米团簇催化硅粉转化为SiC的机理.计算结果表明,Fe,Co及Ni纳米催化剂先与Si形成合金,拉长并弱化Si—Si键的强度,起到活化Si粉的作用;合金的形成有利于C原子的吸附及Si原子和C原子间的反应;Fe的催化能力强于Co和Ni.在此基础上,以Si粉和酚醛树脂为原料,以Fe,Co及Ni硝酸盐为催化剂前驱体,通过微波加热反应制备了3C-SiC纳米粉体.研究了催化剂种类、反应温度、催化剂用量和反应时间等对制备3C-SiC纳米粉体的影响.结果表明,催化剂Fe,Co和Ni的加入均可显著降低3C-SiC的合成温度.当以2.0%(质量分数)的Fe为催化剂时,Si粉在1100℃下反应30 min后即可全部转化为3C-SiC纳米粉体;而在相同条件下,无催化剂时Si粉的完全转化温度为1250℃;Fe的催化效果优于Co和Ni,与DFT计算结果吻合.     

Pyrolysis of Porous Organic Polymers under a Chlorine Atmosphere to Produce Heteroatom-Doped Microporous Carbons

Three types of cross-linked porous organic polymers (either oxygen-, nitrogen-, or sulfur-doped) were carbonized under a chlorine atmosphere to obtain chars in the form of microporous heteroatom-doped carbons. The studied organic polymers constitute thermosetting resins obtained via sol-gel polycondensation of resorcinol and five-membered heterocyclic aldehydes (either furan, pyrrole, or thiophene). Carbonization under highly oxidative chlorine (concentrated and diluted Cl₂ atmosphere) was compared with pyrolysis under an inert helium atmosphere. All pyrolyzed samples were additionally annealed under NH₃. The influence of pyrolysis and additional annealing conditions on the carbon materials’ porosity and chemical composition was elucidated.