石墨烯/聚吡咯复合电极材料超电容性能研究进展

分析了目前石墨烯和聚吡咯(PPy)用作电极材料的不足,详细介绍了近年来超级电容器用石墨烯/PPy复合电极材料的研究进展,指出石墨烯/PPy复合材料在能量转换和存储领域的未来发展方向.     

NiMn2O4/还原氧化石墨烯复合材料的制备及其超级电容性能

采用水热法制备了NiMn₂O₄/还原氧化石墨烯（NiMn₂O₄/rGO）复合电极材料,研究了石墨烯对NiMn₂O₄/rGO材料形貌、微观结构及电化学性能的影响。结果表明：NiMn₂O₄纳米片沉积在石墨烯片的表面,聚集现象消失。与纯NiMn₂O₄相比,NiMn₂O₄/rGO具有高的比表面积和优良的电化学性能。在1A/g时具有1375F/g的比电容,而纯NiMn₂O₄的比电容为924F/g。5000次充放电后,NiMn₂O₄/rGO在5A/g时的比电容保留率为90%,而NiMn₂O₄的比电容保留率为78%。NiMn₂O₄/rGO表现出良好的电容性能,作为超级电容器电极材料具有广泛的应用前景。     

一步水热法合成铜改性的介孔γ-Al_2O_3及其吸附脱硫性能研究

采用一步水热合成法,以Al(NO3)3为铝源,P123为模板剂,Na OH、Na2CO3和K2CO3分别为沉淀剂,Cu(NO3)2为铜源,制备出负载铜的金属有序介孔γ-Al2O3,并运用N2吸附-脱附和XRD等技术对其结构进行表征,同时探讨了铜改性的介孔γ-Al2O3对模型燃油中的噻吩的吸附性能。结果表明,这3种沉淀剂都能制备出比表面积大(>226 m2/g),孔径分布中心为3.3 nm,孔体积为0.27⁰.35 cm3/g的负载铜的介孔γ-Al2O3,且样品都保持了较好的介孔结构。样品对模型燃油中噻吩的吸附脱硫性能表明,用Na OH作为沉淀剂且负载铜的介孔γ-Al2O3样品对噻吩的吸附性能较好,原因在于此样品具有较大的比表面积且铜在此样品中的分散性较好。     

聚吡咯/氧化石墨烯复合材料的制备及电化学性能研究

分别采用物理球磨混合法、化学原位聚合法和化学原位聚合-还原法制备了聚吡咯/氧化石墨烯混合物、聚吡咯/氧化石墨烯(PPy/GO)和聚吡咯/还原氧化石墨烯(PPy/RGO)复合材料。通过三电极测试其电化学性能(循环伏安、恒流充放电和交流阻抗)。结果表明,通过化学原位聚合法制备的PPy/GO(304. 5 F/g)比电容远高于物理混合(16 F/g)和聚吡咯/还原氧化石墨烯(126. 4 F/g)。化学法原位聚合法制备PPy/GO最佳条件是冰浴条件下和加入表面活性剂对羟基苯磺酸钠。并通过X射线衍射(XRD)和扫描电子显微镜(SEM)对化学原位制备的PPy/GO组成、结构和形貌进行了表征。     

用于超级电容器的硫化钴/石墨烯气凝胶复合材料的研究

采用一步水热法,在乙二胺的辅助下,制备了硫化钴/石墨烯气凝胶(CoS/GA)复合材料。通过X射线衍射法(XRD)、扫描电镜(SEM)、电化学性能测试对材料进行了表征和测试。结果表明:制备的材料晶型规整,30～100 nm的CoS粒子均匀地分布在石墨烯气凝胶上。用作超级电容器时,在电流密度0.5 A/g时,CoS/GA复合材料比电容值达574 F/g,是纯CoS的1.4倍;充放电循环1 000次后,比电容保持率为94.4%。硫化钴/石墨烯复合材料的电化学性能较好,具有较大的比电容和较好的循环稳定性,是一种可用于超级电容器的较有潜力的电极材料。     

Electrochemically synthesized polypyrrole and Cu‐plated nylon/spandex for electrotherapeutic pad electrode

Electroconductive fabrics were prepared to improve the properties of conductive electrode pad material used for electrotherapy when it is subjected to various movements of the human body. Highly stretchable and conductive fabrics were prepared by in situ electrochemical polymerization of polypyrrole (PPy) on nylon/spandex stretchable fabric in aqueous solutions with 0.05M pyrrole and 0.05M anthraquinone‐2‐sulfonic acid, sodium salt monohydrate (AQSA) at room temperature for 2 h. Electroless Cu plating was also applied after chemical polymerization of PPy to improve the conductivity of the fabric pad. Performance of prepared stretchable conductive fabric pad was evaluated in terms of conductivity changes as a function of extension and continuous current application time, and clinical test. As a result, the fabric conductivity was well maintained with extension up to 60% and prolonged treatment time over 30 min. The effect of transcutaneous electrical nerve stimulation (TENS) was observed with prepared TENS pad in this study and conventional TENS pad for medical use. The significant effect of TENS was observed with a pad made of conductive fabric by Cu plating and a conventional TENS pad (P < 0.05, respectively). Even though the efficiency of an experimental pad made of fabric composite with electrochemically polymerized PPy was not as good as conventional TENS pad for medical use in this experiment, it can possibly be used for other applications where relatively low‐strength electrical pulse is required. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 4064–4071, 2004     

Interfacial synthesis of polypyrrole/graphene composites and investigation of their optical,electrical and electrochemical properties

We report the development of a novel route for the synthesis of polypyrrole/graphene (PPy/GR) composites by liquid ? liquid interfacial polymerization, where GR and the initiator were dispersed in the aqueous phase and the monomer was dissolved in the organic phase. The synthesized samples were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, ultraviolet–visible spectroscopy, Raman spectroscopy, X‐ray diffraction, thermogravimetric analysis, electrochemical and electrical conductivity measurements. Structural analysis reveals a uniform dispersion of GR sheets in the PPy matrix. The composites showed noticeable improvement in thermal stability and electrical conductivity (8.45 S cm^?1) and excellent electrochemical reversibility in comparison with pure PPy. A specific capacitance of 260 F g^?1 at a current density of 100 mA g^?1 was achieved for the composite during the charge–discharge process. © 2013 Society of Chemical Industry     

Preparation of on chip,flexible supercapacitor with high performance based on electrophoretic deposition of reduced graphene oxide/polypyrrole composites

A new concept is introduced to fabricate flexible, on-chip supercapacitors by electrophoretically depositing highly dispersed reduced graphene oxide/polypyrrole on interdigital-like electrodes. By the unique method, the deposited films could construct on the substrate facilely and uniformly. The prepared all-solid-state device demonstrates high volumetric capacitance (about 147.9 F cm⁻³), high energy density (13.15 mWh cm⁻³ at a power density of 1300 mW cm⁻³) and excellent cycling stability (approximately 71.7% of the initial capacitance retained after 5000 cycles). Compared with other supercapacitor, the device demonstrated here is lightweight, flexible and inexpensive.     

Electroconductive performance of polypyrrole/graphene nanocomposites synthesized through in situ emulsion polymerization

The present study demonstrates a modified in situ emulsion polymerization (EP) approach convenient for the formation of polypyrrole/graphene (PPy/GN) nanocomposites with harnessed conductivities. A series of PPy/GN nanocomposites were prepared by loading different weight percent (wt %) of GN during in situ EP of pyrrole monomer. The polymerization was carried out in the presence of dodecyl benzene sulfonic acid, which acts as an emulsifier and protonating agent. The microstructures of the nanocomposites were studied by scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared, X‐ray photoelectron spectroscopy, UV–vis spectroscopy, Raman spectroscopy, photoluminescence spectroscopy and thermogravimetric analyses. The electrical conductivities of the nanocomposite pellets pressed at different applied pressures were determined using four probe analyzer. The electrical conductivities of the nanocomposites were considerably enhanced as compared to those of the individual PPy samples pressed at the same pressures. An enhanced conductivity of 717.06 S m^?1 was observed in the sample with 5 wt % GN loading and applied pressure of 8 tons. The results of the present study signify that the addition of GN in the PPy polymer harnesses both electrical and thermal properties of the polymer. Thus, PPy/GN nanocomposites with superior properties for various semiconductor applications can be obtained through direct loading of GN during the polymerization process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41800.     

石墨烯/δ-MnO2复合材料的制备及其超级电容器性能

采用螯合法制备了RGO/δ-MnO₂复合材料,并用X射线粉末衍射（XRD）、低压氮气吸附脱附（BET）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、能谱（EDS）、热重（TGA）对其结构和物相进行表征。采用循环伏安测试（CV）、恒电流充放电（GCD）以及循环测试对所制材料电化学储能进行测试。结果表明RGO/δ-MnO₂复合材料比纯石墨烯和纯δ-MnO₂具有更优异的电化学性能。当电流密度为1 A·g^-1时,RGO/δ-MnO₂复合材料的比电容可达322.6 F·g^-1,比纯δ-MnO₂电极材料高234.2 F·g^-1,比纯石墨烯高212.1 F·g^-1。当电流密度放大10倍后,RGO/δ-MnO₂复合材料的比电容保留率为79.1%。在1000次恒流充放电测试后,比电容为252 F·g^-1（99.6%）,说明该方法制备的RGO/δ-MnO₂复合材料是一种有应用前景的超级电容器电极材料。     

Nanodiamond particles/reduced graphene oxide composites as efficient supercapacitor electrodes

The paper reports on the preparation of reduced graphene oxide (rGO) modified with nanodiamond particles composites by a simple solution phase and their use as efficient electrode in electrochemical supercapacitors. The technique relies on heating aqueous solutions of graphene oxide (GO) and nanodiamond particles (NDs) at different ratios at 100 °C for 48 h. The morphological properties, chemical composition and electrochemical behavior of the resulting rGO/NDs nanocomposites were investigated using UV/vis spectrometry, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM) and electrochemical means. The electrochemical performance, including the capacitive behavior of the rGO/NDs composites were investigated by cyclic voltammetry and galvanostatic charge/discharge curves at 1 and 2 A g⁻¹ in 1 M H₂SO₄. The rGO/ND matrix with 10/1 ratio displayed the best performance with a specific capacitance of 186 ± 10 F g⁻¹ and excellent cycling stability.     

Mechanically strong high performance layered polypyrrole nano fibre/graphene film for flexible solid state supercapacitor

Paper like flexible electrode becomes one of the most important research objects recently in request of the fast expanding market of portable electronics. Flexible solid state supercapacitors are shortlisted as one of the most promising energy devices to power electronics with medium to high power density requirements. In this work, we developed a simple but effective way to produce a mechanically strong and electrochemically active RGO/polypyrrole (PPy) fibre paper. A well-bedded microstructure was created with interlaced polypyrrole fibres evenly distributed between the graphene layers. Such microstructure can create enormous amount of pores and therefore provides larger interfaces for charge carrier storage/release. The effects of polypyrrole fibres on the film’s morphologies, mechanical properties and electrochemical performance were discussed. A solid state supercapacitor was demonstrated using such paper electrodes and a gel type electrolyte – phosphate acid (H₃PO₄) infused polyvinyl alcohol (PVA). It showed a high capacitance (345 F g⁻¹) and an excellent cycling stability (9.4% drop after 1000 cycles).     

Electroconductive and catalytic performance of polypyrrole/montmorillonite/silver composites synthesized through in situ oxidative polymerization

The present study demonstrates a simple approach to the formation of polypyrrole/montmorillonite/silver (PPy/Mt/Ag) composites via in situ oxidative polymerization of pyrrole (Py) in the presence of AgNO₃ acting as a direct oxidant. The polymerization was performed in the presence of dodecylbenzenesulfonic acid, which acts as a stabilizing and doping agent. The morphological, structural, and thermal properties of PPy/Mt/Ag composites are discussed in detail and a possible formation mechanism is proposed. The electrical conductivities of the composites pressed at different pressing pressures were investigated using four‐probe analyzer. X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy results indicated the partially exfoliated structure of the composites and Fourier transforms infrared results suggested the strong interactions between Si? O? Si groups in Mt and N? H groups in PPy chains. The addition of Mt in the PPy polymer enhanced thermal property of the polymer. The conductivity of 1.08 S cm^?1 was observed in the sample with 20 wt % Mt loading and applied pressure of 5 MPa. The composites obtained in the present study catalyze the reduction of methylene blue by sodium borohydride, achieving 92% conversion of MB to colorless within a few minutes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45986.     

Carboxylated polyurethane anionomers and their composites with polypyrrole

Some polyurethane anionomers synthesized by a two‐step substitution postreaction of urethane hydrogen atoms with CH₂COONa groups were studied. The influence of ionic structures on the mechanical and electrical properties of polymers was followed. The carboxylated polyurethane anionomers were used to obtain electroconductive composites with polypyrrole, by immersion of polyurethane films in aqueous solution of pyrrole and oxidative chemical polymerization of the heterocyclic monomer with FeCl₃. The proportion of polypyrrole in the composites increased by introduction of ionic groups. Stress–strain behavior and electrical conductivity of composites were compared with those of the anionomers. Incorporation of polypyrrole significantly enhanced the electrical conductivity but diminished mechanical properties. Some composites possess both satisfactory conductivity and mechanical properties. The results were explained by the morphological changes induced by ionic group and polypyrrole presence. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1385–1392, 2000     

Multiwalled carbon nanotubes/polypyrrole/graphene/nonwoven fabric composites used as electrodes of electrochemical capacitor

The reduced graphene oxide/nonwoven fabric (rGO/NWF) composites have been fabricated through heating the NWF coated with the mixture of GO and HONH₂·HCl at 130°C, during which the GO is chemically reduced to rGO. Then the composites of polypyrrole (PPy)/rGO/NWF have been prepared through chemically polymerizing pyrrole vapor by using the FeCl₃·6H₂O adsorbed on rGO/NWF substrate as oxidant. Finally, multiwalled carbon nanotubes (MWCNTs) are used as conductive enhancer to modify PPy/rGO/NWF through dip‐dry process to obtain MWCNTs/PPy/rGO/NWF. The prepared composites have been characterized and their capacitive properties have been evaluated in 1.0M KCl electrolyte by using two‐electrode symmetric capacitor test. The results reveal that MWCNTs/PPy/rGO/NWF possesses a maximum specific capacitance (C_sc) of about 319 F g^?1 while PPy/rGO/NWF has a C_sc of about 277.8 F g^?1 at the scan rate of 1 mV s^?1 and that optimum MWCNTs/PPy/rGO/NWF retains 94.5% of initial C_sc after 1000 cycles at scan rate of 80 mV s^?1 which is higher than PPy/rGO/NWF (83.4%). Further analysis reveals that the addition of MWCNTs can increase the charger accumulation at the outer and inner of the composites, which is favorable to improve the stability and the rapid charge‐discharge capacity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41023.     

Development of supercapacitor active composites by electrochemical deposition of polypyrrole on carbon nanofibres

In this study, pyrrole monomer is polymerized on carbon nanofibres (CNFs) via electropolymerization. This is a new technique to produce a chemically bonded CNF–polypyrrole composite. Deposition of the polypyrrole (PPy) on the nanofibres was optimized by varying the degree of deposition and deposition speed. Optimization studies have proven that the high deposition amounts result in blocks of polymers, which can be overcome through tuning the degree of polymerization by means number of cycles of electropolymerization and the scan rate of the electropolymerization.     

Electrochemically reduced graphene oxide sheets for use in high performance supercapacitors

Graphene oxide (GO) was reduced by a rapid, effective and eco-friendly electrochemical method of repetitive cathodic cyclic potential cycling, without using any reducing reagents. The electrochemically reduced graphene oxide (ERGO) was characterized by UV–vis, EIS and zeta-potential measurements. Most of the oxygen functional groups in ERGO were successfully removed resulting in smaller charge transfer resistance. However, some electrochemically stable residuals still remained, enabling ERGO to facilitate electrolyte penetration and pseudocapacitance. Since ERGO was readily stabilized by cathodic potential cycling, it exhibited an outstanding stability in cycle life, nearly with no capacitive loss from the second cycle on. A specific capacitance of 223.6 F g⁻¹ was achieved at 5 mV s⁻¹, which makes the ERGO a competitive material for electrochemical energy storage.     

Silver nanoparticles decorated polypyrrole/graphene nanocomposite: A potential candidate for next‐generation supercapacitor electrode material

In the present study, we report a simple method to synthesize silver (Ag)‐polypyrrole (PPy)/graphene (Gr) nanocomposite as efficient electrode materials for supercapacitor application. The probable interaction between Ag nanoparticles with both PPy and Gr were characterized by FTIR, UV–visible, and Raman spectroscopies. The morphological analysis confirmed that the Gr sheets are uniformly coated by PPy and in the coated Gr sheets there is the presence of Ag nanoparticles. The Ag‐PPy/Gr nanocomposite achieved the highest specific capacitance of 472 F/g at a 0.5 A/g current density. Better energy and power density also obtained for the nanocomposite. The presence of both Ag nanoparticles and Gr is the main reason for the enhancement of the electrochemical properties of the nanocomposite. Based on the superior electrochemical properties, the nanocomposite can be used for next‐generation supercapacitor electrode material. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44724.