氧化石墨烯纳米带杂化粒子和石墨烯纳米带的研究进展

氧化石墨烯纳米带杂化粒子是将氧化石墨烯纳米带(GONRs)与其他纳米粒子经π-π键、氢键等结合方式复合在一起,通过这种特殊的结合形态一方面可以有效地防止GONRs的聚积,另一方面新的纳米粒子的引入能够赋予该杂化材料某些特殊的性能,从而有利于充分发挥GONRs杂化材料在聚合物改性等领域的综合性能。本文综述了氧化石墨烯纳米带杂化粒子的制备方法、性能和应用现状。此外,针对GONRs的还原产物石墨烯纳米带(GNRs)的结构、性能、制备方法及其应用领域也进行了系统性地论述。相关研究表明,氧化石墨烯纳米带杂化粒子的设计与制备是氧化石墨烯纳米带迈向实用领域的一个有效途径,而石墨烯纳米作为石墨烯的一种特殊结构的二维变体,继承了石墨烯优良的导电和导热等性能,同时特殊的边缘效应,因而呈现出了更广阔的应用潜力。     

石墨烯负载金属氧化物催化剂在氧还原反应中的研究进展EI北大核心

催化剂对氧还原反应(ORR)起到至关重要的作用。近年来,人们为寻找可替代Pt金属的高性能非贵金属催化剂付出了诸多努力。过渡金属氧化物作为具备优异ORR催化活性的催化剂之一,成本低廉、储量丰富,在ORR催化领域具有巨大潜力,因而引起广泛的研究。但由于大部分过渡金属氧化物导电性差,极大地阻碍了其催化活性,所以将其负载于合适的载体上,对提高ORR性能有重要意义。石墨烯以其独特的电子特性、优异的导电性以及其他良好的物理、化学性质被广泛作为载体使用。本文综述了石墨烯负载过渡金属氧化物作为ORR催化剂的研究进展,主要从石墨烯载体分类、制备方法、过渡金属氧化物分类等多角度讨论了该类催化剂在ORR中的应用及发展前景,指出石墨烯负载过渡金属氧化物作为ORR催化剂应致力于将开发杂原子掺杂石墨烯作为载体、复合金属氧化物作为活性物质的主要发展方向,并趋向于降低制备工艺的能耗和周期,提高催化剂的性能,达到降本增效的目的。     

Pd-Sn-Co纳米粒子修饰还原氧化石墨烯/CuBi2O4复合材料的制备及电催化性能

采用水热-浸渍还原法将Pd-Sn-Co纳米粒子固载到氧化石墨烯（GO）/CuBi₂O₄载体上,成功获得Pd-Sn-Co@还原氧化石墨烯(rGO)/CuBi₂O₄复合催化剂,并用于碱性介质中乙二醇的电催化氧化。通过比较单金属Pd、双金属Pd-Co、Pd-Sn及三金属Pd-Sn-Co@rGO/CuBi₂O₄四种负载型催化剂的电催化性能发现,三金属Pd-Sn-Co@rGO/CuBi₂O₄展现出最高的电催化活性和抗毒能力,其正向峰电流密度达到186.54 mA·cm?2,是商用Pd/C (29.57 mA·cm?2)的6.3倍。这种优良的电氧化性能归功于载体GO/CuBi₂O₄独特的三维结构为负载金属提供了充足的界面和活性位点及良好分散性的Pd-Sn-Co三金属纳米粒子之间强烈的协同作用,此外,将GO引入到CuBi₂O₄中有利于多金属纳米粒子的负载并吸附更多的含氧物种,提供优良的电子转移并增大与乙二醇分子的接触面积。这种新型复合材料的制备为发展高效Pd基电催化氧化直接醇类燃料电池提供了新途径,具有较好的理论和应用价值。      

Pt-TiO_2-还原氧化石墨烯纳米复合材料的制备及氧还原性能

制备一种具有高氧还原电催化活性的Pt-Ti O2-还原氧化石墨烯复合材料;采用X射线衍射、扫描电镜、透射电镜、高分辨透射电镜和拉曼光谱分析手段对催化剂的组成和微观结构进行表征。结果表明:氧化石墨烯在复合材料的合成过程中被还原为还原氧化石墨烯,纳米Pt与Ti O2颗粒均匀地附着在还原氧化石墨烯的片层上形成Pt-Ti O2-还原氧化石墨烯复合材料;该复合材料氧还原起始电位为-0.20 V左右,通过Koutecky-Levich方程计算得到电催化过程中复合材料的交换电流密度为10-6~10-5m A/cm2,16 000 s的计时电流测试后其相对电流值高达起始值的88%以上。     

石墨烯负载纳米粒子复合材料的研究进展

石墨烯是一种新型的碳纳米材料,因其独特的二维晶体结构和优异的性能,近年来成为各领域研究的热点.首先概述了石墨烯负载不同纳米金属粒子、纳米金属氧化物或氢氧化物复合材料近年来的研究进展和实际应用,然后提出了石墨烯负载纳米粒子复合材料的未来研究方向,并展望了其可能的应用前景.     

Ni2CoS4/还原氧化石墨烯/多孔还原氧化石墨烯的制备及其在超级电容器中的应用

采用水热法制备Ni_2CoS_4活性材料,通过物理过程和水热反应将其与氧化石墨烯(GO)、水热多孔氧化石墨烯(HHGO)复合得到Ni_2CoS_4/还原氧化石墨烯/多孔还原氧化石墨烯(Ni_2CoS_4/RGO/HRGO)复合电极材料。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、循环伏安测试、恒流充放电测试和交流阻抗测试等,对复合材料的形貌结构、电化学性能进行了表征。研究结果表明:在1 A/g的电流密度下,其比电容为1 684 F/g,在5 A/g的电流密度下循环2 000次后,其比电容保持率为91.8%。Ni_2CoS_4/RGO/HRGO优良的电化学行为归因于这种复合结构使电解液对电极材料的润湿程度提高,进而提高了离子和电荷的传输速率,同时也缓解石墨烯、Ni_2CoS_4的团聚和循环过程中的体积变化。因此,Ni_2CoS_4/RGO/HRGO是一种有良好应用前景的高性能超级电容器电极材料。     

氧化石墨烯原位合成VC及其负载Pt氧还原催化性能

为了开发高性能燃料电池催化剂,研究以氧化石墨烯为载体和碳源合成VC及其负载Pt催化剂的合成、结构和催化氧还原性能。结果表明:氧化石墨烯可以作为碳源在氢气气氛下与V_2O_3原位合成VC,同时在氨气气氛下热处理还可以对其进行氮的掺杂,氮掺杂将其催化氧还原的起始电势提高了0.15V。石墨烯与氮掺杂VC负载Pt具有良好的催化氧还原性能,其峰值电流、起始电势以及循环寿命都超过了传统的Pt-C催化剂。     

氧化石墨烯的还原研究进展

石墨烯自首次被Novoselov和Geim等发现和报道后,因其特殊的光、电、热及力学等优异性能而受到广泛研究。在众多制备石墨烯的方法中,还原氧化石墨烯是目前最有希望实现大规模生产石墨烯的方法。鉴于此,重点回顾和比较了国内外氧化石墨烯的还原方法,其间介绍了部分还原机理,并预测了未来发展的趋势。     

Nano-manufacturing of Co(OH)2@NC for efficient oxygen evolution/reduction reactions

Oxygen evolution and oxygen reduction are considered as essential processes in the energy conversion devices.The progress of cost-effective bifunctional catalysts has become a critical issue to be solved.Here,we report that Co(OH)2@N-doped carbon (NC) was facilely synthesized through the impregnation strat-egy of metal-organic frameworks derived carbon and cobalt ions.N-doped carbon with porous structure and cobalt hydroxide nanosheets play a synergistic effect role,representing excellent catalytic perfor-mance toward oxygen evolution and reduction reactions.The obtained Co(OH)2@NC exhibits remarkable activity in terms of a lower overpotential of 330 mV@10 mA cm-2 for OER and a more positive half-wave potential (E1/2 =0.84 V) for ORR in alkaline medium,outperforming lrO2 and Pt/C.Due to its superior bifunctional catalytic performance,Co(OH)2@NC catalyst is applied into a promising air electrode of Zn-air battery.This presented strategy of impregnation synthesis in this work provides a new design direction for practical electrochemical energy devices.     

Characterization of Pt-Cu binary catalysts for oxygen reduction for fuel cell applications

Nanostructured Pt-Cu/C alloy catalysts synthesized by a reduction procedure with different reducing agents are investigated to find the origin of the enhanced activity of the oxygen reduction reaction for fuel cell applications. Prepared catalysts are characterized by various techniques, such as energy dispersive X-ray spectrometry, X-ray diffraction, transmission electron microscopy (TEM) and cyclic voltammetry. XRD analysis shows that all prepared catalysts exhibit face-centered cubic structures and have smaller lattice parameters than pure Pt catalyst. TEM images show that the particle size of the catalysts increases with the heat treatment temperature, and that different reducing agent causes different particle size and dispersion of the binary catalysts on XC-72R. Using the polyol method with CuSO₄ as the precursor, the Pt-Cu/C sample is found to have good dispersion and high Cu loading. The Pt-Cu/C sample has a slightly higher specific activity value than that of Pt/C. The catalytic activity can be enhanced greatly with hydrogen reduction at 300 °C. Higher reduction temperatures cause the catalytic particles to agglomerate and therefore decreased catalytic activity.     

Shape-controlled synthesis of porous AuPt nanoparticles and their superior electrocatalytic activity for oxygen reduction reaction

Control of structure and morphology of Pt-based nanomaterials is of great importance for electrochemical energy conversions. In this work, we report an efficient one-step synthesis of bimetallic porous AuPt nanoparticles (PAuPt NPs) in an aqueous solution. The proposed synthesis is performed by a simple stirring treatment of an aqueous reactive mixture including K₂PtCl₄, HAuCl₄, Pluronic F127 and ascorbic acid at a pH value of 1 without organic solvent or high temperature. Due to their porous structure and bimetallic composition, as-made PAuPt NPs exhibit excellent electrocatalytic activity for oxygen reduction reaction.     

Nitrogen-doped graphite encapsulated Fe/Fe_3C nanoparticles and carbon black for enhanced performance towards oxygen reduction

Non-noble metal(NNM) catalysts have recently attracted intensive interest for their high catalytic performance towards oxygen reduction reaction(ORR) at low cost.Herein,a novel NNM catalyst was synthesized by the simple pyrolysis of carbon black,urea and a Fe-containing precursor,which exhibits excellent ORR catalytic activity,superior durability and methanol tolerance versus the Pt/C catalyst in both alkaline and acidic solutions.Scanning electron microscopy(SEM),transmission electron microscopy(TEM) and X-ray diffraction(XRD) characterizations demonstrate that the product is a nitrogen-doped hybrid of graphite encapsulated Fe/Fe_3C nanoparticles and carbon black.X-ray photoelectron spectrum(XPS) and electrochemical analyses indicate that the catalytic performance and chemical stability correlate closely with a nitrogen-rich layer on the Fe/Fe_3C nanoparticle after pyrolysis with presence of urea,leading to the same four-electron pathway towards ORR as the Pt/C catalyst.The hybrid is prospective to be an efficient ORR electrocatalyst for direct methanol fuel cells with high catalytic performance at low cost.     

Synthesis and electrocatalytic oxygen reduction properties of truncated octahedral Pt3Ni nanoparticles

Pt₃Ni nanoparticles have been obtained by shape-controlled synthesis and employed as oxygen reduction electrocatalysts for proton exchange membrane fuel cells (PEMFC). The effects of varying the synthesis parameters such as the types of the capping agent and the reducing agent, and the reaction time have been systematically studied. The as-prepared Pt₃Ni nanoparticles were subjected to a butylamine-based surface treatment in order to prepare carbon-supported electrocatalysts. The Pt₃Ni electrocatalysts show an areaspecific activity of 0.76 mA/cm²(Pt) at 0.9 V in an alkaline electrolyte, which is 4.5 times that of a commercial Pt/C catalyst (0.17 mA/cm² (Pt)). The mass activity reached 0.30 A/mg(Pt) at 0.9 V, which is about twice that of the commercial Pt/C catalyst. Our results also show that the area-specific activities of these carbon-supported Pt₃Ni electrocatalysts depend strongly on the (111) surface fraction, which is consistent with the results of a study based on Pt₃Ni extended single-crystal surfaces.     

化学还原法制备纳米银粒子及其表征

采用化学还原法, 通过一系列条件实验,借助紫外-可见分光光度计(UV-vis)得到最佳实验条件,在最佳实验条件下制得紫黑色溶胶,在40℃下真空干燥3h,获纳米银粉.制备的纳米银粉用X射线衍射仪(XRD)和透射电镜(TEM)分析表明,其粒径大小分布范围窄,形状为单一球形,平均粒径为18nm.     

原位负载Pt-Co高指数晶面催化剂的制备及其电催化性能

直接乙醇燃料电池(DEFC)具有燃料易得、绿色高效的优点,得到了广泛的研究,但是DEFC催化剂存在催化效率低、稳定性差的问题,制约了其快速发展。本研究采用液相水热合成法,以聚乙烯吡咯烷酮(PVP k-25)为分散剂和还原剂、甘氨酸为表面控制剂和共还原剂,通过调控Pt-Co金属前驱体的摩尔比,一步制备了XC-72R炭黑负载的Pt₁Co_x/C高指数晶面纳米催化剂,实现了催化剂晶粒在碳载体上的原位生长。Pt₁Co_1/3/C纳米催化剂暴露的高指数晶面主要包括(410)、(510)和(610)晶面。在晶体生长过程中, Pt₁Co_1/3/C纳米催化剂晶粒由“类球体”转变立方块,最终得到具有高指数晶面取向的内凹形貌。Pt₁Co_1/3/C高指数晶面纳米催化剂的电催化活性最高,其电化学活性表面积为18.46 m²/g,对乙醇氧化峰电流密度为48.70 mA/cm²,稳态电流密度为8.29...     

次亚磷酸钠还原法制备纳米铜颗粒

利用液相还原两步法,油酸为萃取荆和保护剂,葡萄糖和次亚磷酸钠将五水硫酸铜分别还原为氧化亚铜和单质铜,制备得到了粒度为50～100nm左右分散均匀的球形纳米铜颗粒,并用XRD、SEM和TEM对其进行了表征.结果表明,在油酸的保护下,采用液相还原两步法可制得分散性好、具有抗氧化性能的球形纳米铜颗粒.     

Carbonized polyaniline nanotubes/nanosheets-supported Pt nanoparticles: Synthesis, characterization and electrocatalysis

Nitrogen-containing carbonized polyaniline nanotubes/nanosheets were used to synthesize a novel type of supported Pt nanoparticles electrocatalyst PtNPs/Carb-nanoPANI, with the Pt nanoparticles of ~ 9 nm in diameter. PtNPs/Carb-nanoPANI nanocomposite was characterized by transmission electron microscopy, cyclovoltammetry, thermogravimetric and XRD analyses. Its electrocatalytic activity towards the oxygen reduction reaction in both the alkaline and acidic solutions was studied by a rotating disc technique. In acidic media, this electrocatalyst was compared to both smooth platinum and commercial C-supported Pt-based electrocatalyst. Its higher specific electrocatalytic activity, which amounted to ~ 1 mA cm^− 2 in the region of diffusion control, was proved. High electrocatalytic activity of PtNPs/Carb-nanoPANI towards the ethanol oxidation reaction in acidic medium was also evidenced.     

On the oxygen reduction reaction catalyzed by Ti -Cu binary films in 0.5 M sulfuric acid solution

Ti-Cu binary films co-sputtered in vacuum are catalytically active for the oxygen reduction in 0.5 M H₂SO₄. The activity for the oxygen reduction reaction (ORR) increased with increasing the Cu-content in the Ti-Cu films and it reached to a maximum with the copper composition up to 90 at.%. The constant Tafel slope of ~ 190 mV/decade which is comparable to that obtained on pure Cu films indicates that the active sites for oxygen reduction is copper sites. Through investigation of Tafel polarization, the Ti-Cu films revealed a constant Tafel slope (i.e., 190 mV/decade) similar to that of ORR on the pure Cu film. This infers that the electrochemical reduction of oxygen is predominated on the Cu-sites in the film. In the cyclic voltammograms, the strong broad peak should have arisen from the oxidation of Cu to Cu⁺ and Cu²⁺ ions. This oxidation indicated that the Ti-Cu films are unstable and the Cu-component is susceptible to dissolution in 0.5 M H₂SO₄. This dissolution caused a loss of catalytic activity in the films. Preparing the Ti-Cu films enriched in Ti will stabilize these films to prevent the Cu-dissolution.