氮掺杂石墨烯@碳纳米纤维的原位制备及其电催化氧还原性能

结合静电纺丝和热处理技术, 在含钴碳纳米纤维上原位生长了氮掺杂石墨烯, 制备了三维互通纤维网结构。研究了钴含量对产物氧还原活性的影响。结果表明: 氮掺杂石墨烯的生成和钴的引入均显著提高了电催化活性。纺丝液中六水合硝酸钴与聚丙烯腈的质量比为1: 10时, 获得的催化剂活性最优, 起始电势为0.84 V(vs RHE), 反应为近四电子路径, 具有比铂碳更好的稳定性和耐甲醇毒化能力。三维互通结构促进了电子和质子传输, 并能提供更多的活性位点, 提高电催化活性。这种方法也可用于设计其它三维互通的纤维复合物, 在能源与环境领域具有更广泛的应用前景。     

氮掺杂氧化石墨烯的制备及其氧还原催化性能研究

以腺嘌呤为掺杂氮源,以均苯三酸为辅助碳源,采用水热法对多层氧化石墨烯进行氮掺杂,在惰性气氛下煅烧得到氮掺杂氧化石墨烯(NGO),重点研究了腺嘌呤用量对产物的氧还原催化性能的影响。利用上海辰华电化学工作站,采用线性扫描伏安法对其氧还原催化性能进行测试分析,并利用Koutecky-Levich方程对其氧还原电子转移数进行计算。结果表明,以腺嘌呤作为氮源能够大幅度地提高氧化石墨烯的催化性能,当腺嘌呤用量为6 mmol时,所制得的氮掺杂氧化石墨烯NGO-3的催化性能最好,催化氧气还原以4e~-途径进行。     

氮掺杂石墨烯的制备及应用

氮掺杂石墨烯具有独特的性能,被广泛应用于电子设备、光伏产业和传感器等领域。首先通过对目前氮掺杂石墨烯的主要制备方法进行分析和讨论,探讨了不同维度的氮掺杂石墨烯的结构和性能,并总结了氮掺杂石墨烯的应用范围。而后,基于目前的研究现状指出氮掺杂石墨烯将会面临的挑战及未来的发展趋势。     

S/N共掺杂石墨烯的制备及其电催化性能

采用一步水热法制备了S/N共掺杂石墨烯催化剂材料。利用扫描电子显微镜(SEM)、透射电镜(TEM)、拉曼光谱、红外光谱以及X射线衍射仪(XRD)对催化剂物理形貌、组成、物相等进行了分析,并利用电化学分析方法对催化剂的电催化性能进行了研究。通过不同的物理表征证明S和N成功地掺杂入石墨烯晶格,共掺杂石墨烯具有典型的石墨烯形貌。掺杂石墨烯的高电催化活性是源于对石墨烯进行S和N的掺杂后仍然具有高比表面积及石墨烯本身所特有的一些性质。该掺杂石墨烯在0.1 mol/L的KOH溶液中对氧进行催化还原时,无论是起始电位、半波电位、还是极限电流密度,都可与商业生产的贵金属催化剂相媲美,说明S/N共掺杂石墨烯在氧还原催化活性上可被用来替代当前所使用的贵金属催化剂。     

Co/MR氮掺杂炭气凝胶的制备、结构及氧还原性能

以三聚氰胺、间苯二酚、甲醛为原料,采用溶胶-凝胶法、冷冻干燥等步骤制备出三聚氰胺-间苯二酚-甲醛(MR)干凝胶;并以所制炭气凝胶为载体浸渍硝酸钴,经氮气中高温炭化,得到钴复合氮掺杂的炭气凝胶。考察间苯二酚和三聚氰胺比例、凝胶pH值及炭化条件等对气凝胶结构和催化氧还原活性的影响,采用XRD、XPS、低温氮气吸脱附等方法研究催化剂的结构。随pH值增加,MR气凝胶的介孔分布向小孔移动;当M/R物质的量比为6∶1时,其介孔分布为3.0~4.0 nm。钴复合炭气凝胶多孔结构中存在均匀分布Co金属颗粒和管状炭,Co金属颗粒粒径随炭化温度升高而增加。采用旋转圆盘电极研究催化剂在0.5mol/L H2SO4溶液中的电化学性能,结果表明催化剂具有良好的氧还原活性。     

氮掺杂空心碳纳米球嵌入氮掺杂石墨烯负载钯纳米粒子作为甲酸氧化的高效电催化剂（英文）

低成本、高活性、耐久性好的高效电催化剂对直接甲酸燃料电池的应用起着至关重要的作用。本文采用简单经济的方法,研究了以三维层状多孔结构嵌入氮掺杂石墨烯(NG)的氮掺杂空心碳纳米球(NHCN)负载Pd纳米粒子作为直接甲酸燃料电池催化剂。由于具有独特的氮原子掺杂三维互联层状多孔结构,Pd纳米颗粒尺寸较小的Pd/NHCN@NG催化剂具有较大的催化活性表面积、优越的电催化活性、较高的稳态电流密度和较强的抗CO中毒能力,明显超过传统的Pd/C、Pd/NG和Pd/NHCN催化剂对甲酸电氧化的催化性能。通过优化HCN/GO比,当HCN/GO质量比为1∶1时,Pd/NHCN@NG催化剂对甲酸的催化氧化性能最佳,其活性是Pd/C的4.21倍。本工作开发了一种优越的碳基电催化剂载体材料,为燃料电池的发展带来了广阔的应用前景。     

氮掺杂水热碳/石墨烯复合膜的制备及其性能研究

以废弃柚子皮瓤和氧化石墨烯(GO)为碳源,氨水为掺杂剂,采用水热与真空抽滤相结合的方法,制备氮掺杂石墨烯(N-G)、氮掺杂水热碳膜(N-HC)和氮掺杂水热碳/石墨烯复合膜[N-HC/G-X,X=1、2、4、5,X代表柚子皮瓤(g)与GO(mg)的质量比],利用扫描电镜、X射线衍射、拉曼光谱和红外光谱表征碳材料的物理化学性质,并进行了吸附Zn(Ⅱ)和截留Cr(Ⅵ)的实验。结果表明：N-G、N-HC和N-HC/G-X均为典型片层结构,N-HC是获得薄膜的必要成分,N-HC/G-1和N-HC/G-2的成膜效果优于N-HC/G-4和N-HC/G-5,N-HC/G-1的膜厚度大约为65μm, C、N和O的质量分数分别为65.63%、15.06%和19.31%。N-G、N-HC和N-HC/G-X都是无定形碳材料,N-HC的d₀₀₂片层间距最大,随着N-HC/G-X中N-G质量的逐渐增多,N-HC/G-X的片层间距逐渐减小,表面缺陷和混乱程度有所增大,且N-HC/G-X表面存在大量的含氧和含氮官能团,可以提供更多活性吸附位点,有利于提升对重金属的吸附效果。N-HC/G-1和N-...     

Facile synthesis of porous nitrogen-doped holey graphene as an efficient metal-free catalyst for the oxygen reduction reaction

Nano Research - Nitrogen-doped graphene is a promising candidate for the replacement of noble metal-based electrocatalysts for oxygen reduction reactions (ORRs). The addition of pores and holes...     

Microbial reduction of graphene oxide and its application in microbial fuel cells and biophotovoltaics

Despite more than a decade of study, there are still significant obstacles to overcome before graphene can be successfully produced on a large scale for commercial use. Chemical oxidation of graphite to produce graphene oxide (GO), followed by a subsequent reduction process to synthesize reduced graphene oxide (rGO), is considered the most practical method for mass production. Microorganisms, which are abundant in nature and inexpensive, are one of the potential green reductants for rGO synthesis. However, there is no recent review discussing the reported microbial reduction of GO in detail. To address this, we present a comprehensive review on the reduction of GO by a range of microorganisms and compared their efficacies and reaction conditions. Also, presented were the mechanisms by which microorganisms reduce GO. We also reviewed the recent advancements in using microbially reduced GO as the anode and cathode material in the microbial fuel cell (MFC) and algal biophotovoltaics (BPV), as well as the challenges and future directions in microbial fuel cell research.     

Scalable fabrication and active site identification of MOF shell-derived nitrogen-doped carbon hollow frameworks for oxygen reduction

Nitrogen-doped carbon materials as promising oxygen reduction reaction(ORR) electrocatalysts attract great interest in fuel cells and metal-air batteries because of their relatively high activity, high surface area, high conductivity and low cost. To maximize their catalytic efficiency, rational design of efficient electrocatalysts with rich exposed active sites is highly desired. Besides, due to the complexity of nitrogen species, the identification of active nitrogen sites for ORR remains challenging. Herein, we develop a facile and scalable template method to construct high-concentration nitrogen-doped carbon hollow frameworks(NC), and reveal the effect of different nitrogen species on theirORRactivity on basis of experimental analysis and theoretical calculations. The formation mechanism is clearly revealed, including low-pressure vapor superassembly of thin zeolitic imidazolate framework(ZIF-8) shell on ZnO templates,in situ carbonization and template removal. The obtained NC-800 displays better ORR activity compared with other NC-700 and NC-900 samples. Our results indicate that the superior ORR activity of NC-800 is mainly attributed to its content balance of three nitrogen species. The graphitic N and pyrrolic N sites are responsible for lowering the working function, while the pyridinic N and pyrrolic N sites as possible active sites are beneficial for increasing the density of states.     

Electrochemical catalytic activity for oxygen reduction reaction of nitrogen-doped carbon nanofibers

The electrocatalytic activity of nitrogen-doped carbon nanofibers (N-CNFs), which are synthesized directly from vaporized acetonitrile over nickel-iron based catalysts, for oxygen reduction reaction (ORR), was investigated. The nitrogen content and specific surface area of N-CNFs can be controlled through the synthesis temperature (300-680 degrees C). The graphitization degree of N-CNFs also are significantly affected by the temperature, whereas the chemical compositions of nitrogen species are similar irrespective of the synthesis conditions. From measurement of the electrochemical double layer capacitance, the surface of N-CNFs is found to have stronger interaction with ions than undoped-carbon surfaces. Although N-CNFs show higher over-potential than Pt catalysts do, N-CNFs were observed to have a noticeable ORR activity, as opposed to the carbon samples without nitrogen doping. The activity dependency of N-CNFs on the content of the nitrogen with which they were doped is discussed, based on the experiment results. The single cell of the direct methanol fuel cell (DMFC) was tested to investigate the performance of a membrane-electrode assembly that includes N-CNFs as the cathode catalyst layer.     

A Prussian blue route to nitrogen-doped graphene aerogels as efficient electrocatalysts for oxygen reduction with enhanced active site accessibility

Developing high-performance nonpredous-metal electrocatalysts for the oxygen reduction reaction (ORR) is crudal for a variety of renewable energy conversion and storage systems.Toward that end,rational catalyst design principles that lead to highly active catalytic centers and enhanced active site accessibility are undoubtedly of paramount importance.Here,we used Prussian blue nanoparticles to anchor Fe/Fe3C species to nitrogen-doped reduced graphene oxide aerogels as ORR catalysts.The strong interaction between nanosized Fe3C and the graphitic carbon shell led to synergistic effects in the ORR,and the protection of the carbon shell guaranteed stability of the catalyst.As a result,the aerogel electrocatalyst displayed outstanding activity in the ORR on par with the state-of-the-art Pt/C catalyst at the same mass loading in alkaline media,good performance in acidic media,and excellent stability and crossover tolerance that rivaled that of the best nonprecious-metal ORR electrocatalysts reported to date.     

磷氮掺杂石墨烯层封装FeP纳米颗粒的增强ORR催化性能

开发高效的非贵金属氧还原反应(ORR)催化剂来替代铂基催化剂受到了广泛关注.设计合成在碱性电解质和酸性电解质中均表现出高催化活性的非贵金属催化剂仍然是一个挑战.在本文中,我们通过前驱体热解法制备了一种纳米复合催化剂(FeP@PGL),该催化剂由氮掺杂的碳纳米片以及镶嵌在片层上的磷掺杂石墨烯层封装磷化铁(FeP)纳米颗粒组成.FeP@PGL催化剂表现出优异的ORR催化性能,在碱性介质中的起始电位和半波电势分别高达1.01 V和0.90 V vs.RHE;在酸性介质中的起始电位和半波电势分别高达0.95 V和0.81 V vs.RHE.通过详细的电子显微和谱学表征,我们发现碳纳米片基质与包裹纳米颗粒的碳包裹层存在组成的差别,磷掺杂主要发生在包裹FeP纳米颗粒的石墨烯层上.封装的FeP纳米颗粒与外层磷掺杂石墨烯层之间存在界面电荷转移,并且通过界面相互作用降低了催化剂表面的功函数.FeP和磷掺杂石墨烯层之间的界面协同作用对于增强催化剂ORR活性至关重要.本文不仅证明了封装型FeP基纳米复合催化剂在氧还原反应上的应用价值,而且为界面电荷转移效应及其在ORR过程中的作用提供了实验证据.     

Functionalized graphene oxide and multi-walled carbon nanotubes in hexadecyl trimethyl ammonium bromide and chitosan matrix as metal-free catalyst for enhanced oxygen reduction reaction

The development of new catalysts for high-performance and cost-effective oxygen reduction is crucial in the commercialization of fuel cells. Herein, we demonstrate the use of a novel metal-free catalyst, hexadecyl trimethyl ammonium bromide (CTAB)-functionalized graphene oxide (GO) and multi-walled carbon nanotubes (MWCNT) in CTAB and chitosan matrix (CTAB/GO/MCWNT/CS), which exhibits a significant synergistic catalytic effect on oxygen reduction reaction. Compared with commercially available Pt/C catalysts, enhanced electrocatalytic activity, improved long-term operational stability, and excellent tolerance to methanol in alkaline fuel cells were observed for the novel composite catalyst.     

High-quality single-layer graphene via reparative reduction of graphene oxide

Reduction of graphene oxide (GO) is a promising low-cost synthetic approach to bulk graphene, which offers an accessible route to transparent conducting films and flexible electronics. Unfortunately, the release of oxygen-containing functional groups inevitably leaves behind vacancies and topological defects on the reduced GO sheet, and its low electrical conductivity hinders the development of practical applications. Here, we present a strategy for real-time repair of the newborn vacancies with carbon radicals produced by thermal decomposition of a suitable precursor. The sheet conductivity of thus-obtained single-layer graphene was raised more than six-fold to 350–410 S/cm (whilst retaining >96% transparency). X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy revealed that the conductivity enhancement can be attributed to the formation of additional sp²-C structures. This method provides a simple and efficient process for obtaining highly conductive transparent graphene films.     

Synthesis and electrocatalytic activity of Au@Pd core-shell nanothorns for the oxygen reduction reaction

Bimetallic core-shell nanostructures with porous surfaces have drawn considerable attention due to their promising applications in various fields, including catalysis and electronics. In this work, Au@Pd core-shell nanothorns （CSNTs） with rough and porous surfaces were synthesized for the first time through a facile co-chemical reduction method in the presence of polyallylamine hydrochloride （PAH） and ethylene glycol （EG） at room temperature. The size, morphology, and composition of Au@Pd CSNTs were investigated by transmission electron microscopy （TEM）, X-ray diffraction （XRD）, energy dispersive spec- troscopy （EDX）, EDX mapping, and X-ray photoelectron spectroscopy （XPS）. The electrochemical properties of as-synthesized Au@Pd CSNTs were also studied by various electrochemical techniques. Au@Pd CSNTs exhibited remarkably high electrocatalytic activity and durability for the oxygen reduction reaction （ORR） in the alkaline media, owing to the unique porous structure and the synergistic effect between the Au core and Pd shell.     

高压釜热还原制备稳定分散的石墨烯溶液

以天然鳞片石墨为原料,用改进的Hummers法制备氧化石墨。超声分散制备氧化石墨烯溶液,通过加入不同量的水合肼调节溶液的pH值,再通过水热法热还原,制备了在水中稳定分散的石墨烯溶液。利用扫描电子显微镜(SEM)、高分辨透射电镜(HR-TEM)、拉曼光谱(Raman)、原子力显微镜(AFM)、X射线衍射分析(XRD)、zeta电位及光学显微镜对制备的样品进行了表征,研究了不同温度、pH值对石墨烯溶液稳定性的影响。