多巴胺改性聚吡咯衍生掺氮多孔碳材料的制备及其超电容性能

含氮聚合物材料在惰性气氛下热解能够产生掺氮多孔碳材料. 基于化学聚合法合成多巴胺(DA)改性的聚吡咯(PDA-PPy), 高温热解制备出掺氮多孔碳材料(NPC). 用傅里叶变换红外(FTIR)光谱, 拉曼光谱, X射线光电子能谱(XPS)分析和扫描电镜(SEM)研究其结构与形貌. 随着DA 与吡咯(Py)单体的摩尔比不断变化,PDA-PPy的形貌也随之改变, 进而影响NPC的超电容性能. 循环伏安和恒流充放电测试表明, 当DA与Py 单体的摩尔比为0.5时, 在0.5 A·g^-1的电流密度下, NPC的比电容可以达到210 F·g^-1, 电流密度为10 A·g^-1时, 比电容可以达到134 F·g^-1, 电容保持率为63.8%.     

超级电容器炭电极材料孔结构对其性能的影响

采用无瓶颈的系列酚醛树脂活性炭为电极材料，用氮吸附和恒流充、放电，以及交流阻抗法，研究孔径和孔表面积等孔结构对其性能的影响.结果表明，活性炭电极材料双电层电容与微孔(孔宽度< 2.0 nm)表面和外孔(孔宽度 >2.0 nm)表面都有关系，但主要取决于微孔表面双电层电容.微孔表面比电容为21.4 μF•cm－2，外孔表面比电容< 10 μF•cm－2.外孔表面比电容较低可能是由于空间电荷层的影响.微孔孔径较大的炭材料具有高比电容和良好的高倍率放电的特性.     

聚苯胺改性氮掺杂碳纳米管制备及其超级电容器性能

利用苯胺原位化学聚合合成聚苯胺包覆碳纳米管(CNTs), 再炭化处理制备氮掺杂碳纳米管(NCNTs).激光拉曼(Raman)光谱和X射线光电子谱(XPS)分析及透射电镜(TEM)观察表明, 苯胺包覆碳纳米管经炭化处理后, 得到以碳纳米管为核、氮掺杂碳层为壳, 具有核-壳结构的氮掺杂碳纳米管, 而碳纳米管本征结构未遭破坏. 研究表明, 随着苯胺用量的增大, 氮掺杂碳纳米管的氮掺杂碳层变厚, 氮含量从7.06%(质量分数)增加到8.64%, 而作为超级电容器电极材料, 随着氮掺杂碳层厚度降低, 氮掺杂碳纳米管在6 mol·L^-1氢氧化钾电解液中的比容量从107 F·g^-1增大到205 F·g^-1, 远高于原始碳纳米管10 F·g^-1的比容量, 且聚苯胺改性氮掺杂碳纳米管表现出较好的充放电循环性, 经1000次充放电循环后仍保持初始容量的92.8%~97.1%, 表明氮掺杂碳纳米管不仅通过表面氮杂原子引入大的法拉第电容和改善亲水性使电容量显著增大, 其具有的核壳结构特征也使循环稳定性增强。     

壳聚糖制备多孔炭及其在电化学超级电容器中的应用(英文)

以壳聚糖为原料在 600、700、800和900℃直接炭化制备多孔炭 C-600,C-700, C-800 和C-900,其BET比表面积分别为278、461、515和625 m2·g-1.用恒流充放电和循环伏安法表征了其电化学性能. 结果表明, 由 C-800 制备电极的循环伏安图形更接近矩形, 在恒电流充放电实验中阴极和阳极过程基本对称, 说明该电极具有较好的电容性能.在 50 mA·g-1 的电流密度下,C-600、C-700、C-800和C-900的电容分别为96、120、154 和 28 F·g-1.由 C-800 制备电极的循环充放电稳定性好, 电流密度为1 A·g-1循环1000次后电容损失小于2%,说明壳聚糖制备多孔碳具有作为超级电容器电极材料的潜在价值. 同时还考察了不同浓度的电解液对C-800电化学性质的影响,发现在KOH浓度为 30%时的电容最大.依据实验结果,对多孔炭制备及其电化学性质间的关系进行了探讨.     

碳气凝胶的孔结构及其对电化学超级电容器性能的影响

通过改变碳气凝胶的溶胶-凝胶制备条件和炭化活化工艺,实现了对碳气凝胶纳米孔洞结构的控制.采用扫描电子显微镜(SEM)和氮气等温气体吸附法对碳气凝胶和KOH活化碳气凝胶的形貌和孔结构进行了表征和分析,并且使用循环伏安法(CV),恒流充放电,电化学阻抗谱(EIS)等检测技术评价了电化学性能.结果表明:发达的三维纳米网络结构与合理的孔径分布是影响碳气凝胶电化学超级电容器性能的关键因素.经适度活化后的碳气凝胶材料含有丰富的介孔,比表面积可达1480m2·g-1.在6mo·lL-1的KOH溶液中,在100mV·s-1的扫描速率下其比电容量高达216F·g-1.通过拟合发现,碳气凝胶类材料的大孔和介孔拥有更高的单位面积比电容量.     

静电纺丝制备多孔碳纳米纤维及其电化学电容行为

采用静电纺丝技术,以聚丙烯腈(PAN)/醋酸锌为前驱体制备复合纳米纤维,随后经碳化、酸化获得多孔碳纳米纤维.扫描电子显微镜(SEM)观察发现,碳纳米纤维表面分布大量孔洞.N2吸脱附等温曲线(BET)测试材料比表面积达413m2·g-1.循环伏安法(CV)和恒流充放电(CP)性能测试表明:多孔碳纳米纤维具有较好的电化学性能,在1A·g-1的电流密度下比电容达275F·g-1.相比碳纳米纤维比容量提高了162%.     

木质素多孔碳材料在电化学储能中的应用

木质素可再生资源成本低、含碳量高、芳香度高和易集中收集,被认为是具备潜力大规模工业化制备新型多孔碳材料的重要碳质原料之一,对缓解化石资源消耗及可持续发展具有重大的意义。多孔碳材料具有较高的电导率、较高的比表面积、丰富的孔道结构及良好的稳定性等特点,作为储能材料有广阔的应用前景。本文介绍了模板法、活化法及水热法制备木质素多孔碳材料的国内外最新研究进展,详细总结了不同热解工艺参数对木质素多孔碳材料微观结构的影响规律,重点阐述了其作为锂离子电池、钠离子电池和超级电容器电极材料的研究进展。针对功能化木质素多孔碳材料制备工艺复杂及储能性能差等瓶颈问题,提出离子/电子扩散动力学的优化、多种储能机制的协同作用和绿色、简便制备工艺的开发等研究策略,指出研发先进炭化技术构筑合理分级孔径结构,精准调控适宜层间距且高度有序排列碳层、功能化改性表面微环境及直接构建炭化工艺参数与电化学性能之间的因效关系是制备高储能性能木质素多孔碳材料的未来研究方向。     

Development of the Self-doping Porous Carbon and Its Application in Supercapacitor Electrode

The massive discharge of biomass wastes not only causes waste of resources, but also pollutes the environment. Therefore, converting biomass wastes into carbon materials is an effective way to solve the above problems. Here, using biomass waste pig nails as raw materials and K₂CO₃ as chemical activators, the N-doped porous carbon(KPNC) is prepared by direct pyrolysis. As an electrode for supercapacitors, the electrochemical tests of KPNCs showed that they exhibited good electrochemical performance and excellent cycling stability. When the current density is 0.2 A/g, the specific capacitance is up to 344.6 F/g. Moreover, it still maintains 97.6% initial capacitance retention after 2000 cycles at a high current density of 5 A/g. Above exceptional electrochemical performances may be ascribed to an appropriate porous structure(S_micro/S_total=80.31%, V_micro/V_total=76.19%), high nitrogen contents(4.44%, atomic fraction), oxygen contents(9.13%, atomic fraction) as well as small internal resistance. The above experimental results show that the conversion of pig nails to porous carbon can reduce the waste of resources and alleviate environmental pollution.     

Nanomolar Level Acetaminophen Sensor Based on Novel Polypyrrole Hydrogel Derived N‐doped Porous Carbon

This study develops a novel approach to morphology‐controlled N‐doped porous carbons (NPC) derived from supramolecular crosslinked polypyrrole hydrogel (PPy‐gel) with tetra‐functional tetrakis(4‐carboxyphenyl)porphyrin as dopant and cross‐linker. Both optimized PPy‐gel and NPC realize acetaminophen determination at nanomolar level, displaying record‐low respective detection limits of 3.0 and 1.0 nM (S/N=3). The optimized NPC demonstrates necklace‐like structure with more edge pyridinic N, revealing better electronic conductivity and higher electrochemically active surface area, and consequently higher sensitivity and selectivity. Even in the presence of three interferences (ascorbic acid, dopamine and uric acid), NPC based electrochemical sensor also shows the ultra‐low detection limit (1.2 nM). The promising application potential of the sensor is proved by the high consistence between measurements in pharmaceutical sample and established acetaminophen standard curve. Moreover, the determination results of acetaminophen in human urine sample obtained by this sensor were in a good agreement with the reference values assayed by HPLC.     

Multi-stage Ordered Mesoporous Carbon-graphene Aerogel-Ni3S2/Co4S3 for Supercapacitor Electrode

Transition metal sulfides have emerged as promising materials in supercapacitor. In this work, we firstly developed an interface-induced superassembly approach to fabricate NiS_x and CoS_x nanoparticles, which based on ordered mesoporous carbon-graphene aerogel composites for supercapacitor electrodes. The obtained multi-component superassembled nanoparticles-carbon matrix composites have controllable 3D porous structure of multi-stage composite. The two-dimensional graphene interlaced to form a 3D framework with large sponge-like pores, and then the graphene surface was loaded with mesoporous carbon with mesoporous pore size and vertical orientation. The composites display high specific capacitance of 958.1 F g⁻¹ at 0.1 A g⁻¹. The capacitance retains about 97.3 % after 3000 charging-discharging cycles at 2 A g⁻¹. These results indicate that the obtained OMC−GA−Ni₃S₂/Co₄S₃ is a promising material for electrochemical capacitors, which providing new technical methods and ideas for the research of new energy and analytical sensor materials in the fields of energy storage, photocatalysis, point-of-care testing devices and other fields.     

Hierarchical Porous NiCo2O4 Microboxes Constructed by Low-Dimensional Substructures for Electrochemical Supercapacitor

The design and synthesis of new materials/structures for high-performance electrochemical capacitors (ECs) is an ongoing challenge. Herein, a hierarchical porous NiCo₂O₄ microbox superstructure made of low-dimensional substructures was reported. The as-prepared NiCo₂O₄ microboxes are constructed by 2D nanosheets building units, which are futher woven by 0D nanoparticles and 1D nanowires. Such microbox superstructures combine the merits of all material dimensions in electrochemical capacitors, such as high porosity, sufficient active sites, and fast mass and charge transport. Benefiting from the structural advantages, the resultant NiCo₂O₄ microbox electrode exhibits ultra-high capacitor performance, i.e., the initial capacitance of 1820 F · g^–1 and 96.6 % capacitance retention after 4000 cycles at 5 A · g^–1.     

When High-Temperature Cesium Chemistry Meets Self-Templating: Metal Acetates as Building Blocks of Unusual Highly Porous Carbons

Self-templating is a facile strategy for synthesizing porous carbons by direct pyrolysis of organic metal salts. However, the method typically suffers from low yields (<4%) and limited specific surface areas (SSA<2000 m² g⁻¹) originating from low activity of metal cations (e.g., K⁺ or Na⁺) in promoting construction and activation of carbon frameworks. Here we use cesium acetate as the only precursor of oxo-carbons with large SSA of the order of 3000 m² g⁻¹, pore volume approaching 2 cm³ g⁻¹, tunable oxygen contents, and yields of up to 15 %. We unravel the role of Cs⁺ as an efficient promoter of framework formation, templating and etching agent, while acetates act as carbon/oxygen sources of carbonaceous frameworks. The oxo-carbons show record-high CO₂ uptake of 8.71 mmol g⁻¹ and an ultimate specific capacitance of 313 F g⁻¹ in the supercapacitor. This study helps to understand and rationally tailor the materials design by a still rare organic solid-state chemistry.     

Porous NiCo2O4 Nanowire Arrays as Supercapacitor Electrode Materials with Extremely High Cycling Stability

In this work, NiCo₂O₄(NCO) was synthesized via microwave hydrothermal method and a further annea- ling treatment. Research results have shown that the surface defects(Co²⁺ site) and pore size of the materials can be adjusted by simply changing the calcination temperatures, and porous nanowire arrays structure can be obtained. The porous structure is conducive to the penetration of the electrolyte and enables the NCO to fully participate in the electrochemical reaction. What's more, the NCO material has ample space to buffer the volume change in the cycle test, improving the cycling stability. The NCO obtained at 350℃ has better performance. It exhibits a specific capacitance of 648.69 F/g at 1 A/g and good rate capability. Especially, at 10 A/g, the specific capacitance can still be maintained at 80.00% after 10000 galvanostatic charge/discharge(GCD) cycles, showing excellent cycling stability.     

水溶性壳聚糖制备多孔碳/氧化镍复合材料及其电化学电容行为

将水溶性壳聚糖碳化得到多孔碳材料, 然后制备了多孔碳/NiO复合材料. 透射电子显微镜(TEM), X射线衍射(XRD)和N₂吸-脱附实验等结构表征显示, 材料具有富含介孔的孔道结构. 循环伏安(CV), 恒流充放电等电化学测试表明, 复合材料具有良好的电化学电容性能. 其中Ni/C质量比为2:20时, 复合材料在0.1 A·g^-1电流密度下比容量可达355 F·g^-1, 而且经过1500次循环比容量仍保持99%左右, 表现出良好的循环稳定性.     

电致变色型导电聚苯胺固态超级电容器的构建与性能研究

以苯胺硫酸溶液为沉积液,导电玻璃(FTO)为基底材料,在-0.2~1.2 V范围内先电位扫描一圈生成聚苯胺(PANI)晶种,然后在-0.2~0.8 V范围内用循环伏安法电沉积导电PANI材料.所得样品用红外光谱和扫描电子显微镜进行结构表征;以最佳循环伏安电沉积条件制备的PANI/FTO为活性电极,以H_2SO_4/聚乙烯醇(H2SO4/PVA)为凝胶电解质组装了电化学电容器,通过循环伏安、恒电流充放电和电化学阻抗法研究了组装电化学电容器的电化学性能.研究结果表明,以H_2SO_4/PVA凝胶电解质,沉积于导电玻璃表面的PANI活性电极材料的面比电容可达172.7 m F/cm~2,并且在2000次充放电以后,比电容值仍可保留初始值的92.8%.以分区沉积有PANI的导电玻璃可组装制备通过变色显示充放电过程的电化学电容器,在充电时,其颜色逐渐从浅绿色向深绿色转变,放电时,颜色逐渐从深绿色向浅绿色转变.     

Recent Advances of Porous Solids for Ultradilute CO2 Capture

The urgency of dealing with global climate change caused by greenhouse gas(GHG) emissions is increasing as the carbon dioxide(CO₂) concentration in the atmosphere has reached a record high value of 416 ppm(parts per million). Technologies that remove CO₂ from the surrounding air(direct air capture, DAC) could result in negative carbon emissions, and thus attracts increasing attention. The steady technical progress in adsorption-based CO₂ separation greatly advanced the DAC, which largely relies on advanced sorbent materials. This review focuses on the latest development of porous solids for air capture; first discussed the main types of sorbents for air capture, which include porous carbons, zeolites, silica materials, and metal-organic frameworks(MOFs), particularly their modified counterparts. Then, we evaluated their performances, including uptake and selectivity under dry and humid CO₂ streams for practical DAC application. Finally, a brief outlook on remaining challenges and potential directions for future DAC development is given.     

Recent Development of Bio-inspired Porous Materials for Catalytic Applications

Nature has served as a source of inspiration for chemists to design the catalysts with superior performance via mimicking their characteristics, such as active sites, reaction microenvironment and electron transfer behaviors. Over a few decades, many different types of materials have been widely used to construct the biomimetic catalysts. Among these materials, the porous materials have been demonstrated to be powerful platforms for constructing the biomimetic catalysts owing to their high surface area, controllable composition and easy functionalization. In this review, we briefly showed recent advances in the construction of various biomimetic porous catalysts using porous materials for the design of excellent catalysts. In addition, we also present the challenge and opportunities in this emerging field.     

纳米碳点的制备与应用研究进展

纳米碳点是碳纳米材料家族的新成员,近年来在国内外受到广泛关注。与传统的荧光染料和半导体量子点发光材料相比,碳点不仅具有优异的光学性能及尺寸效应,且具有制备成本低廉、生物相容性好、易于官能化、能带结构可调等优势。本文在理清有关碳点概念的基础之上,介绍了碳点结构特征和制备策略,着重综述了纳米碳点在生物成像与诊疗、传感器件、催化、光电器件和能量存储领域的最新研究进展,探讨了碳点研究目前存在的问题及未来的发展方向。     

纳米MnO2超级电容器的研究

用固相合成法制备纳米MnO2，作为超级电容器材料，通过循环伏安、交流阻抗与恒电流充放电等测试手段对MnO2电极进行分析.结果表明,以1 mol•L－1 KOH为电解液， MnO2电极在－0.1～0.6 V(vs. Hg/HgO)的电压范围内具有良好的法拉第电容性能.在不同电流密度下，电极比容量达240.25到325.21 F•g－1.恒电流充放电5000次后，电极容量衰减不超过10％.     

纤维素纳米晶模板法制备多级孔炭材料及其电化学性能

以纤维素纳米晶(CNC)为模板,酚醛树脂为碳源,KOH为活化剂,通过高温碳化制备了多级孔炭材料.采用透射电子显微镜(TEM)、扫描电子显微镜(SEM)和X射线光电子能谱仪(XPS)等手段对合成的一系列炭材料进行了表征.结果表明,前驱体中CNC的降解会形成与CNC直径相当的介孔,KOH活化则会导致炭材料产生大量的微孔和大孔,以及部分4 nm左右较小尺度的介孔,所制备炭材料呈现明显的多级孔特性,其比表面积达554.7 m²/g,总孔体积为0.323 cm³/g.以CNC为模板,KOH活化的炭材料作为电极材料时,在1.0 A/g电流密度下其比电容达202.8 F/g,当电流密度升高至40.0 A/g时,其电容保持率仍达69%,表明该炭材料具有优异的倍率性能;由该电极材料组装的超级电容器在10000次充放电循环后,电容保持率达95%以上,具有良好的循环稳定性.