螺线型碳纳米纤维基整体式催化剂活性载体

本工作采用一种简便的一步化学气相沉积(chemical vapor deposition, CVD)法,在泡沫镍基底上直接生长螺线形碳纳米纤维（CNFs/NF）作为对析氧反应有活性的整体式催化剂载体。在1 mol/L KOH为电解质溶液的三电极电解池中,与 CNFs/NF电极材料电化学表面积(ECSA)成正比的的双层电容Cdl值达到13.69 mF/cm2。通过循环伏安法,电化学阻抗谱和线性扫描伏安曲线等电化学手段,验证了CNFs/NF适于做具有析氧反应活性的催化剂载体。CNFs/NF需要260 mV,385 mV的析氧反应过电势以实现10 mA/cm2和100 mA/cm2的电流密度。     

螺线形碳纳米纤维基整体式催化剂活性载体

以乙炔为原料,采用一步化学气相沉积法在泡沫镍(NF)基底上制备了覆盖碳纳米纤维(CNFs)的整体式催化剂载体(CNFs/NF).采用SEM、TEM、XRD、Raman、XPS对CNFs/NF进行了表征,在1 mol/L KOH溶液中使用线性扫描伏安法、循环伏安法、电化学阻抗谱对其电化学性能进行了测试.结果表明,螺线形碳...     

碳基载体石油馏分加氢脱硫催化剂研究进展

总结了以活性炭、碳纳米管、介孔碳、石墨烯等碳基材料为载体的加氢脱硫催化剂的研究进展。与常规Al₂O₃基载体催化剂相比,碳基载体催化剂比表面积大,活性金属的分散性好,活性金属-碳表面间的相互作用弱,有利于形成高活性的Ⅱ类活性相。以二苯并噻吩及4,6-二甲基二苯并噻吩等含硫有机物为处理对象,碳基载体加氢脱硫催化剂总体上具有比Al₂O₃基载体催化剂更高的加氢脱硫催化活性。为满足碳基载体加氢脱硫催化剂的工业应用要求,需要降低制备成本,并针对催化体系的特点进行孔结构优化及表面改性,同时,还需要加强对碳基加氢催化剂加氢脱硫反应机理和动力学方面的研究,以促进催化剂与工艺技术的进步。     

金属催化剂对碳纳米纤维结构影响的研究进展

综述了不同种类的金属催化剂及同种催化剂不同状态对碳纳米纤维的结构和形貌的影响,并对今后自组装生产各种结构形态的碳纳米纤维进行了展望。     

碳纳米球纤维基电极材料的制备及性能研究

将一维纳米纤维索纤维(NCFs)作为MoS2的有效分散剂,通过超临界二氧化碳干燥和高温碳化过程制备碳纳米球纤维(CNPFs)/MoS2纳米杂化气凝胶电极材料.利用SEM、EDS、FT-IR和电化学测试等手段对杂化电极材料的组成、结构和电化学性能进行表征.结果 表明,一定量的NCFs是MoS2的稳定分散剂,可以有效阻碍M...     

近几年整体式催化剂的开发与应用

介绍整体式催化剂相较于传统催化剂的优越性以及在汽车尾气与环保、强吸热/放热及耦联催化重整反应、脂交换反应、烃类燃烧或氧化反应中的研究及应用。阐述整体式催化剂结构性能及相关数学建模方面的最新研究。通过对整体式催化剂制备及应用的系统分析,提出整体式催化剂仍需解决工艺繁琐、活性成分负载困难和内部结构不明确等观点。同时,整体式催化剂可对催化剂研发提供一种切实可行的解决问题的方法和思路。     

炭涂层型整体式催化剂的研究进展

碳元素是一切有机生命体的骨架元素,由其演变而成的炭材料具有多样性,一直以来都备受研究。炭材料来源广泛,具备高比表面积、发达孔隙结构以及良好热-化学稳定性等特征。因此,被广泛运用于催化、吸附和分离等诸多领域。尤其是作为催化剂载体,在很多反应中都展现出优异的性能。然而传统催化剂的形态限制了其在多相连续反应中的应用,对此,有学者尝试将炭材料与整体式框架结构有机结合。制备得到的新型炭涂层型整体式催化剂,有效地弥补了传统催化剂形态上的缺陷,进一步拓宽了其应用范围。基于此,将对炭涂层型整体式催化剂的制备方法和研究现状进行阐述,详细介绍该催化剂的实际应用效果以及影响其性能的相关因素,最后对炭涂层型整体式催化剂的研究前景进行展望。     

多孔碳纳米球及其负载金属催化剂的研究进展

多孔碳纳米球由于可实现尺寸、形貌、孔结构以及表面基团等的可控合成制备,其负载/镶嵌的金属粒子又兼具高活性和高热稳定性等,在多相催化领域中受到越来越多的关注。本文追溯了多孔碳纳米球形貌调控的发展历程及其负载金属催化剂在催化反应领域中的应用。归纳了不同形貌的多孔碳纳米球及其制备方法和原理,详细对比了各个方法的优缺点;阐述了多孔碳纳米球负载金属催化剂的性能和碳球结构与形貌之间的构效关系;总结了目前碳球作为催化剂载体亟需解决的问题是碳球的多孔结构及其负载尺寸可控和空间匀称分布的金属粒子的可控合成,并展望了其发展方向是进一步研究和探索结构可调、经济可行的碳纳米球制备方法,真正实现工业化应用。     

表面修饰的碳载体应用于燃料电池催化剂的研究进展

燃料电池催化剂研究已成为当前的国际热点研究课题。综述了碳材料的表面氧化修饰、表面物质掺杂、表面共价接枝修饰、有机物的非共价包覆,以及将其应用于燃料电池催化剂载体的研究进展,并对存在的问题进行了分析。     

Effects of electrospun polyacrylonitrile-based carbon nanofibers as catalyst support in PEMFC

This paper reports novel results regarding the effects of electrospun carbon nanofibers (e-CNF) as a catalyst support by comparison with the commercial Vulcan XC-72R (denoted as XC-72R) as granular particles. The e-CNF was synthesized by stabilizing and carbonizing the electrospun PAN-based fibers. The e-CNF showed an average diameter of 250 nm with a rough surface and was partially aligned along the winding direction of the drum winder. The characteristic morphology was fundamentally dependant on the shape of the carbon materials. The average pore size of the e-CNF was 2.36 nm, while that of the XC-72R was 10.92 nm. The morphology of e-CNF was developed by shallow pores with rough surfaces due to the effects of electrospinning and carbonization, while that of the XC-72R was largely developed by mesopores rather than micropores due to the granular shape. Compared to XC-72R, the performance of the MEA prepared by e-CNF was excellent, owing to the morphology and the enhanced electrical conductivity. The Pt utilization of Pt/e-CNF was 69%, while that of Pt/XC-72R was 35%.     

Graphene-reinforced metal-organic frameworks derived cobalt sulfide/carbon nanocomposites as efficient multifunctional electrocatalysts

Developing cost-effective electrocatalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is vital in energy conversion and storage applications. Herein, we report a simple method for the synthesis of graphene-reinforced CoS/C nanocomposites and the evaluation of their electrocatalytic performance for typical electrocatalytic reactions. Nanocomposites of CoS embedded in N, S co-doped porous carbon and graphene (CoS@C/Graphene) were generated via simultaneous sulfurization and carbonization of one-pot synthesized graphite oxide-ZIF-67 precursors. The obtained CoS@C/Graphene nanocomposites were characterized by X-ray diffraction, Raman spectroscopy, thermogravimetric analysis-mass spectroscopy, scanning electronic microscopy, transmission electronic microscopy, X-ray photoelectron spectroscopy and gas sorption. It is found that CoS nanoparticles homogenously dispersed in the in situ formed N, S co-doped porous carbon/graphene matrix. The CoS@C/10Graphene composite not only shows excellent electrocatalytic activity toward ORR with high onset potential of 0.89 V, four-electron pathway and superior durability of maintaining 98% of current after continuously running for around 5 h, but also exhibits good performance for OER and HER, due to the improved electrical conductivity, increased catalytic active sites and connectivity between the electrocatalytic active CoS and the carbon matrix. This work offers a new approach for the development of novel multifunctional nanocomposites for the next generation of energy conversion and storage applications.     

Anodes for glucose fuel cells based on carbonized nanofibers with embedded carbon nanotubes

Electrodes made of carbonized polyacrylonitryle (cPAN) nanofibers, with and without embedded multiwall carbon nanotubes (MWCNTs) were fabricated by the electrospinning (ES) process and evaluated as anodes in glucose fuel cell (FC) application. The effect of several processing and structural characteristics, such as the presence of MWCNTs, polymer concentration in the ES solution and silver electroless plating on FC performance were measured. The carbon electrodes were successful as anodes showing significant activity even without additional silver catalyst, with noticeable improvement by the incorporation of MWCNTs. The orientation of graphitic layers along the fiber axis and the coherence of layer packing were shown to be important for enhanced electrode activity. The maximal values of open circuit voltage (OCV) and peak of power density (PP_D) of unmetalized electrodes, 0.4 V and 30 μW/cm² respectively, were found to be for composite cPAN/CNT electrode. Electroless silver metallization of the carbon nanofiber electrodes leads to much better FC performance. Maximal values of OCV and PP_D of silvered carbon electrodes were measured to be about 0.9 V and 400 μW/cm², respectively. Thus, carbonized nanofibers with embedded MWCNTs may form a good basis for glucose FC anodes, but better metallization and cell-configuration allowing proper mixing are required.     

Enhancement of electrosorption capacity of activated carbon fibers by grafting with carbon nanofibers

The composite films of activated carbon fibers (ACFs) and carbon nanofibers (CNFs) are prepared via chemical vapor deposition of CNFs onto ACFs in different times from 0.5 to 2 h and their electrosorption behaviors in NaCl solution are investigated. The morphology, structure, porous and electrochemical properties are characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, N₂ adsorption at 77 K, contact angle goniometer and electrochemical workstation, respectively. The results show that CNFs have been hierarchically grown on the surface of ACFs and the as grown ACF/CNF composite films have less defects, higher specific capacitances, more suitable mesoporous structure and more hydrophilic surface than the pristine ACFs, which is beneficial to their electrosorption performance. The ACFs/CNFs with CNFs deposited in 1 h exhibit an optimized NaCl removal ratio of 80%, 55% higher than that of ACFs and the NaCl electrosorption follows a Langmuir isotherm with a maximum electrosorption capacity of 17.19 mg/g.     

Novel Pd-carrying composite carbon nanofibers based on polyacrylonitrile as a catalyst for Sonogashira coupling reaction

Novel Pd-carrying composite carbon nanofibers based on polyacrylonitrile were prepared by electrospinning and carbonization process. The catalytic activities of the composite nanofibers were tested with a Sonogashria coupling reaction of iodobenzene and phenylacetylene in liquid-phase. Transmission electron microscope and X-ray diffraction analyzer were used to characterize the nanofibers and the metal nanoparticles on the fibers; gas chromatograph and nuclear magnetic resonance spectroscopy were used to characterize the product of the testing reaction. The results first showed that the catalyst not only had a high catalytic activity, but also had good leaching-resistance, retrieval and reusability for the Sonogashira reaction.     

竹制活性炭作为催化剂载体的研究

利用SEM、N₂-物理吸附和联碱滴定法等表征手段系统比较了竹质活性炭和普通竹炭与其他材质活性炭在物化性能方面的异同,同时利用CO-化学吸附考察了这些材料作为催化剂载体对负载钯催化剂金属钯分散度的影响。实验结果表明,竹质活性炭在比表面积、孔结构、灰分含量和表面基团等物化性能方面都已具备作为催化剂载体的条件,显示出成为新催化剂载体的潜力。     

Chain confinement in electrospun nanofibers of PET with carbon nanotubes

Composite nanofibers of poly(ethylene terephthalate), PET, with multiwalled carbon nanotubes (PET/MWCNT) were prepared by the electrospinning method. Confinement, chain conformation, and crystallization of PET electrospun (ES) fibers were analyzed as a function of the weight fraction of MWCNTs. For the first time, we have characterized the rigid amorphous fraction (RAF) in polymer electrospun fibers, with and without MWCNTs. The addition of MWCNTs causes polymer chains in the ES fibers to become more extended, impeding cold crystallization of the fibers, resulting in more confinement of PET chains and an increase in the RAF. The fraction of rigid amorphous chains greatly increased with a small amount of MWCNT loading: with addition of 2% MWCNTs, RAF increased to 0.64, compared to 0.23 in homopolymer PET ES fibers. Spatial constraints also inhibit the folding of polymer chains, resulting in a decrease in crystallinity of PET. For fully amorphous PET/MWCNT composites, MWCNTs do not affect the chain conformation of PET in the ES fibers. For cold crystallized PET/MWCNT composite nanofibers, more trans conformers were formed with the addition of MWCNTs. The increase of RAF (chain confinement) is associated with an increase of the concentration of the trans conformers in the amorphous region as the MWCNT concentration increases in the semicrystalline nanofibers.     

氮掺杂碳纳米材料在氧还原反应催化剂中的研究进展

长期以来,碳材料负载高分散的铂催化剂及其合金材料一直是商业化质子交换膜燃料电池（PEMFC）中氧还原反应和氢氧化反应十分有效的催化剂。但由于Pt基催化剂成本高、电化学条件下稳定性差、易CO中毒以及氧还原反应（ORR）动力学迟缓等一系列问题,阻碍了其在燃料电池中的进一步应用和大规模生产。相比之下,氮掺杂碳纳米材料具有低成本、高活性、高稳定性、环境友好等特点,这些优异的性能使其在燃料电池领域有着广阔的应用前景。结合近几年国内外研究现状,综述了原位掺杂法、后掺杂合成法和直接热解法等3种氮掺杂碳纳米材料的制备方法,并分析了各自的优点和不足之处,及其作为ORR催化剂的研究进展。最后,对未来氮掺杂碳纳米材料催化剂研究的主要发展方向进行了展望。