A composite polyaniline/graphene–coated polyamide6 nanofiber mat for electrochemical applications

In this study, polyamide6 (PA6) nanofiber mats were fabricated through the electrospinning process. The nanofibers were coated by polyaniline (PANI) using the in situ polymerization of aniline in the presence of graphene oxide. The composite of the PANI/graphene oxide–coated nanofiber mat was treated with hydrazine monohydrate to reduce graphene oxide to graphene, and this was followed by the reoxidation of PANI. Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), wide angle X‐ray diffraction (WAXD), thermal gravimetric analysis (TGA), tensile strength tests, electrical conductivity measurements, cyclic voltammetry (CV), and charge/discharge measurements were conducted on the composite PA6/graphene nanofiber mats. It was found that the surface of the PA6 nanofibers was coated uniformly with the granular PANI and graphene oxide. Besides, the composite nanofibers showed good tensile and thermal properties. Their electrical conductivity and specific capacitance, when used as a separator in the cell, were 1.02 × 10^?4 S/cm and 423.28 F/g, respectively. Therefore, the composite PANI/reduced graphene oxide–coated PA6 nanofiber mats could be regarded as suitable candidates for application in energy storage devices.     

Polyaniline‐coupled graphene/nickel hydroxide nanohybrids as flame retardant and smoke suppressant for epoxy composites

Graphene‐polyaniline/nickel hydroxide ternary hybrid (RGO‐PANI/Ni(OH)₂) was synthesized and incorporated into epoxy resin (EP) to improve the fire retardant property. Thermogravimetric analysis results showed that the RGO‐PANI/Ni(OH)₂ nanohybrid could catalyze the thermal degradation of epoxy matrix that was essential to trigger the char formation. The char yield of the RGO‐PANI/Ni(OH)₂/EP composite was improved compared with that of the samples with graphene and polyaniline only. With 3.0‐wt% RGO‐PANI/Ni(OH)₂, significant reduction in peak heat release rate (40%) and peak smoke production rate (36%) was observed in the cone calorimeter tests. Thermogravimetric analysis/infrared spectrometry (TG‐IR) results indicated that the flammable volatiles of the RGO‐PANI/Ni(OH)₂/EP composite was reduced compared with those of the EP and RGO‐PANI/EP. The superior flame retardant and smoke suppressant behaviors of the RGO‐PANI/Ni(OH)₂ nanohybrid over RGO‐PANI were attributed to the combination of good barrier effect of graphene with catalytic ability of char formation of PANI and metal hydroxide.     

One‐Step Electrodeposition to Layer‐by‐Layer Graphene–Conducting‐Polymer Hybrid Films

One‐step fabrication of graphene–polyaniline (graphene–PANI) hybrid film was facilely achieved by cyclic voltammetric electrolysis of a bath containing both graphene oxide (GO) and aniline, where graphene is obtained by electrochemical reduction of GO and PANI is simultaneously obtained by aniline electropolymerization. As there is no strong attraction between aniline and GO under the electrodeposition conditions, the independent depositions of PANI and reduced GO nanosheets at their greatly differed potentials led to alternate layered graphene–PANI films, with the topmost layer being PANI particles or graphene sheets just by changing the initial scan directions. The two kinds of graphene–PANI hybrid films present excellent but different electrical and electrochemical behaviors.     

Effect of electrostatic forces control on the structure and properties of polyaniline/graphene oxide nanocomposite

The effects of electrostatic forces (EF), control on the morphology, structure, and electrochemical properties of polyaniline, PANI/graphene oxide (GO), nanocomposites prepared by interfacial electropolymerization (IEP), are studied in this work. FESEM images showed that the IEP method can form the PANI/GO nanocomposites when the EF-control has been found mainly on the PANI nanofibers formation and growth on the GO film surface; and the EF-enhancement can form PANI nanofibers with small nano-diameter, longer length, uniform morphology, high order and well orientation as compared with the EF-reduction-formed sample. The EF-enhancement-formed PANI/GO nanocomposite showed improved electrochemical properties than that of the EF-reduction-formed sample due to the EF-enhancement that enhances the C–N structure for PANI/GO nanocomposite.     

石墨烯/聚苯胺复合材料的制备及应用

石墨烯/聚苯胺复合材料由于其优异的电学、热学、电化学性能和机械性能等特点,吸引了研究者们的广泛关注。本文对近几年来石墨烯/聚苯胺复合材料的发展状况进行了简单介绍,首先总结了原位聚合法、界面聚合法、自组装法、溶液共混法等不同制备方法对石墨烯/聚苯胺复合材料结构和性能的影响。由于石墨烯/聚苯胺复合材料结合了石墨烯和聚苯胺两者的优点,展现出更加优异的性能,因此本文还对其在超级电容器、传感器、燃料电池、太阳能电池等方面的应用进行了详细介绍。     

Physicochemical interactions between polyaniline and graphene oxide: the reasons for the stability of their chemical structure and thermal properties

Several works are reported in the literature on the use of a conducting polymer such as polyaniline (PANI) and its combination with graphene oxide (GO). Graphene derivatives have an important contribution to improve the electrochemical performance of charge transfer and polarization of the polymer in energy storage cells. To understand the chemical phenomena in PANI–GO interaction, this article presents the relationships of the thermal, chemical, and morphostructural properties of this composite material. This synergistic effect between the materials is responsible for performance enhancing. Therefore, in this work, after PANI electrosynthesis on carbon fiber and further dipping of GO, Field Emission Gun, Raman spectroscopy, X-Ray Excited Electron Photon Spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, Differential Scanning Calorimetry, and thermogravimetric techniques were used to characterize these materials. GO tends to stabilize the molecular structure of PANI in its protonation/deprotonation and redox processes. Through thermal analysis, it was possible to observe that GO increases the stability of PANI at higher temperatures, minimizing mass loss rates and changing the polymer's glass transition temperature. And when observing the structure of the material under the influence of temperature, the GO kept the structures practically unaltered (PANI crystallographic orientation) up to 150 °C. These facts highlight important material stability data to be considered in energy storage system applications.     

Graphene oxide-modified polyaniline pigment for epoxy based anti-corrosion coatings

In the present work, a set of polyaniline–graphene oxide (PANI–GO) nanocomposites which exhibit superior properties in terms of shelf life, processability and conductivity due to the synergistic effect of GO and PANI, have been synthesized by varying the concentration of highly non-conducting GO with respect to aniline. The obtained materials were characterized by UV–Vis, FTIR, XRD, Raman, TGA as well as FESEM, TEM analysis. The results reveal that nanocomposites show better dispersibility, crystallinity, thermal stability, and conductivity. Further, the synthesized composites have been tested for their anti-corrosion properties. The potentiodynamic results reveal that PANI nanocomposites with 1% GO exhibited long-term anti-corrosion behavior with a corrosion rate of 6.5 × 10^?5 mm year^?1, which is much lower than its individual components and commercial-grade red oxide. Also, it possesses highest impedance modulus ~33 kΩ cm² and real impedance ~32 kΩ cm², maximum coating resistance ~14.81 × 10³ Ω cm² and minimum coating capacitance after 96 h of immersion in 3.5% mass NaCl than those exhibited by all other coated samples. Higher concentration of GO could not retard the corrosion rate confirming that hydrophilicity of GO play an important role in the redox mechanism of PANI.     

Bio-waste derived,phosphorus decorated composite for highly efficient flame retardant for cotton fabric

In this, an efficient flame retardant composite has been prepared using biowaste derived phosphorous groups decorated graphene supported nanomaterial. The eggshell was utilized as a source of calcium carbonate, which was converted to monocalcium phosphate (CP) by phosphoric acid treatment. As-prepared monocalcium phosphate was functionalized with graphene to prepare graphene functionalized monocalcium phosphate (GCP). The GCP-coated fabric didn't ignite during the flame test and sustained more than 600 s on continuous exposure to flame without changing its initial length and shape. Whereas, graphene oxide (GO), and CP coated cotton fabric burnt out very easily within a short time. The efficient flame retardant property of as synthesized GCP coated cotton fabric was confirmed with a high limiting oxygen index (34.1) and char length of 2.5 cm was generated from the VFT test. The synthesized GCP coated cotton fabric also confirmed efficient flame retardant properties. This facile method enables an easy process for mass production of cost-effective, bio-waste derived nanomaterial for a significantly highly efficient candidate for different applications in sustainable chemistry, including flame-retardant applications.

Graphical abstract

     

氧化石墨掺杂的电化学活性自支撑聚苯胺膜

以氧化石墨（GO）为掺杂剂和模板,采用化学原位聚合法并通过调节苯胺单体和氧化石墨的质量比,合成了层状结构的聚苯胺/氧化石墨(PANI/GO)层状结构的自支撑膜。SEM和XRD研究表明,当苯胺单体与GO的质量比为67:1时,PANI/GO复合材料具有层间距~1.36 nm的层状结构,证实 GO的模板功能。XPS和FTIR研究表明PANI/GO复合材料中的典型的聚苯胺的掺杂态,进一步证实GO的掺杂功能。此外,电化学和热失重测量表明PANI/GO层状结构的自支撑膜呈现良好的热稳定性和高电化学活性.     

A platinized stainless steel fiber with in‐situ coated polyaniline/polypyrrole/graphene oxide nanocomposite sorbent for headspace solid‐phase microextraction of aliphatic aldehydes in rice samples

The surface of a stainless steel fiber was made larger, porous and cohesive by platinizing for tight attachment of its coating. Then it was coated by a polyaniline/polypyrrole/graphene oxide (PANI/PP/GO) nanocomposite film using electrochemical polymerization. The prepared PANI/PP/GO fiber was used for headspace solid‐phase microextraction (HS‐SPME) of linear aliphatic aldehydes in rice samples followed by GC‐FID determination. To achieve the highest extraction efficiency, various experimental parameters including extraction time and temperature, matrix modifier and desorption condition were studied. The linear calibration curves were obtained over the range of 0.05–20 μg g⁻¹ (R ² > 0.99) for C₄–C₁₁ aldehydes. The limits of detection were found to be in the range of 0.01–0.04 μg g⁻¹. RSD values were calculated to be <7.4 and 10.7% for intra‐ and inter‐day, respectively. The superiority of the prepared nanocomposite SPME fiber was established by comparison of its results with those obtained by polydimethylsiloxane, carbowax–divinylbenzene, divinylbenzene–carboxen–polydimethylsiloxane and polyacrylate commercial ones. Finally, the nanocomposite fiber was used to extract and determine linear aliphatic aldehydes in 18 rice samples.     

自支撑石墨烯/聚苯胺纳米纤维薄膜的制备及其电化学电容行为

用真空抽滤氧化石墨（GO）与聚苯胺（PANI）纳米纤维的混合分散溶液,流动组装得到自支撑GO/PANI复合薄膜,再利用气态水合肼还原其中的GO,最后重新氧化和掺杂还原态PANI,制备了自支撑石墨烯（GN）/PANI薄膜.扫描电子显微镜（SEM）结果显示,GN/PANI薄膜为层状结构,且PANI纳米纤维均匀插层于GN片间.PANI纳米纤维在复合薄膜中的存在有效增大了GN之间的层间距,有利于电解液离也GN充分接触.GN的高电导性则有利于PANI氧化还原过程中的电荷传输.电化学测试表明,GN/PANI薄膜在1 mol·L^-1HCl电解液中具有良好的电化学电容性能,在0.1 A·g^-1的电流密度下的比容量为495 F·g^-1,在3A·g^-1时为313 F·g^-1.经过2000次连续充放电,其具有90%的电容保持率,表明该复合材料具有良好的电化学稳定性.     

Three-dimensional nitrogen and phosphorous Co-doped graphene aerogel electrocatalysts for efficient oxygen reduction reaction

The development of efficient electrocatalysts for oxygen reduction reaction (ORR) is of importance for fuel cells and metal-air batteries. Herein, three-dimensional nitrogen and phosphorous co-doped graphene aerogel (NPGA) was prepared via the pyrolysis of polyaniline (PANi) coated graphene oxide aerogel synthesized by oxidative polymerization of aniline on graphene oxide (GO) sheets in the presence of phytic acid. The uniform coating of PANi thin layer on the surface of GO sheets enables the formation of highly porous composite aerogel of PANi and GO. The subsequent thermal treatment is able to prepare the porous NPGA due to the carbonization of PANi and phytic acid as nitrogen and phosphorous resources. When used as electrocatalysts, the as-prepared NPGA electrocatalysts exhibited good catalytic activity to ORR via an efficient four-electron pathway with good stability, benefiting from the highly porous structure and the heteroatom co-doping. More importantly, Zn-air batteries operated in ambient air have been fabricated by coupling a Zn plate with the NPGA electrocatalyst in an air electrode, demonstrating the maximal power density as high as ～260 W/g and a good long-term stability with slightly potential decay for over 450 h. The facile method for preparing efficient carbon based ORR electrocatalysts would generate other potential applications including fuel cells and others.     

聚苯胺/石墨烯涂覆型阴离子交换固定相的制备及表征

该文以聚苯胺/石墨烯复合材料为涂覆材料,制备了一种涂覆型阴离子交换固定相。首先以苯胺和石墨烯为原料制备聚苯胺/石墨烯复合材料,并通过物理吸附涂覆在聚苯乙烯-二乙烯苯微球表面;然后以聚苯胺中的氮原子为反应位点,通过季铵化制备一系列具有不同交换容量的涂覆型阴离子交换固定相。通过扫描电镜(SEM)、傅里叶红外光谱(FT-IR)和元素分析(EA)对该涂覆型阴离子交换固定相进行表征,结果表明聚苯胺/石墨烯成功地涂覆在微球表面且发生了季铵化。通过分离常规阴离子和有机酸,对自制阴离子交换色谱柱的色谱性能进行评价。结果显示,8次季铵化的聚苯胺/石墨烯涂覆聚苯乙烯-二乙烯苯阴离子交换色谱柱对常规阴离子和有机酸呈现良好的分离效果。     

Microfluidic fabrication of polysiloxane/dimethyl methylphosphonate flame‐retardant microcapsule and its application in silicone foams

A novel and versatile route for fabricating flame‐retardant microcapsules via microfluidics technology is reported. The flame‐retardant microcapsules were prepared with a dimethyl methylphosphonate (DMMP) core and an ultraviolet‐curable (UV‐curable) polysiloxane shell. Furthermore, a UV‐curable polysiloxane was synthesized. The synthesis mechanism of UV‐curable polysiloxane and the curing mechanism of flame‐retardant microcapsules were analyzed. To verify that DMMP was encapsulated in the microcapsules, X‐ray fluorescence was used before and after microencapsulation. The resulting microcapsules were well monodispersed and exhibited a good spherical shape with a smooth surface. In addition, the size of the microcapsules decreased dramatically with an increasing flow‐rate ratio of the middle‐/inner‐phase or outer‐phase flow rate. The thermal stability of the microcapsules was worse than shell materials but superior to DMMP. Silicone foams (SiFs) with microcapsules prepared using a dehydrogenation method achieved a relatively higher limiting oxygen‐index value than the pure SiF, which indicated that the microcapsules could enhance the flame retardation of SiFs effectively. Because of the polysiloxane shell, the microcapsules had good compatibility with SiFs, and the influence of microcapsules on the mechanical properties of SiFs was unremarkable.     

Surface and Interface Engineering of Graphene Oxide Films by Controllable Photoreduction

We report herein the engineering of the surface/interface properties of graphene oxide (GO) films by controllable photoreduction treatment. In our recent works, typical photoreduction processes, including femtosecond laser direct writing (FsLDW), laser holographic lithography, and controllable UV irradiation, have been employed to make conductive reduced graphene oxide (RGO) microcircuits, hierarchical RGO micro‐nanostructures with both superhydrophobicity and structural color, as well as moisture‐responsive GO/RGO bilayer structures. Compared with other reduction protocols, for instance, chemical reduction and thermal annealing, the photoreduction strategy shows distinct advantages, such as mask‐free patterning, chemical‐free modification, controllable reduction degree, and environmentally friendly processing. These works indicate that the surface and interface engineering of GO through controllable photoreduction of GO holds great promise for the development of various graphene‐based microdevices.     

Preparation of graphene oxide modified glass fibers and their application in flame retardant polyamide 6

In order to improve the flame retardancy of glass fibers (GFs) reinforced polyamide 6 (PA6) composites and eliminate the “wicking effect,” the preparation and application of graphene oxide (GO) modified GFs were investigated in this work. Flame retardant PA6 was prepared by blending graphene oxide modified GFs reinforced PA6 and aluminum diethyl phosphonate. For the GFs reinforced PA6, the limiting oxygen index of the composite increased from 20.6% to 22.3%, and peak heat release rate decreased by 37.2% in cone calorimeter test via introducing graphene oxide onto the surface of GFs. Comparing PA6/GF30/ADP15 and PA6/GF‐GO30/ADP15, LOI of the later increased to 31.2%, the vertical burning test (UL‐94) reached V‐0, and the peak heat release rate decreased by 18.0%. The interface compatibility was greatly improved after the introduction of GO. The sheet structure of the GO on the GFs surface could block the combustible gas spillage and the flow of melt along the GFs, thus significantly attenuating the “wicking effect” and improving the flame retardancy of composites.     

Controllable Preparation of Polyaniline–Graphene Nanocomposites using Functionalized Graphene for Supercapacitor Electrodes

In order to explore the effect of graphene surface chemistry on electrochemical performance based on polyaniline–graphene hybrid material electrodes, four different polyaniline–graphene nanocomposites were fabricated with graphene oxide, reduced graphene oxide, aminated graphene and sulfonated graphene as carriers, respectively. The nanocomposites feature various structures and morphologies, which could be used to more deeply understand the morphology and structure effects caused by surface chemistry on electrochemical performance. The experimental results reveal that functionalized electronegative graphene was conducive to the vertical and neat growth of polyaniline (PANI) nanorods. The array architecture endowed the PANI–GS nanocomposite with a large ion‐accessible surface area and high‐efficiency electron‐ and ion‐transport pathways. Meanwhile, the introduction of sulfonic acid functional groups accelerated the redox reaction with doping and dedoping of the PANI. Thereby, the PANI–GS nanocomposite exhibited a high specific capacitance of 863.2 F g^?1 at a current density of 0.2 A g^?1 and the excellent rate capability of 67.4 % (581.6 F g^?1 at 5 A g^?1), which were much better than the other three nanocomposites produced.     

Single-layered graphene oxide nanosheet/polyaniline hybrids fabricated through direct molecular exfoliation

In this study, we used direct molecular exfoliation for the rapid, facile, large-scale fabrication of single-layered graphene oxide nanosheets (GOSs). Using macromolecular polyaniline (PANI) as a layered space enlarger, we readily and rapidly synthesized individual GOSs at room temperature through the in situ polymerization of aniline on the 2D GOS platform. The chemically modified GOS platelets formed unique 2D-layered GOS/PANI hybrids, with the PANI nanorods embedded between the GO interlayers and extended over the GO surface. X-ray diffraction revealed that intergallery expansion occurred in the GO basal spacing after the PANI nanorods had anchored and grown onto the surface of the GO layer. Transparent folding GOSs were, therefore, observed in transmission electron microscopy images. GOS/PANI nanohybrids possessing high conductivities and large work functions have the potential for application as electrode materials in optoelectronic devices. Our dispersion/exfoliation methodology is a facile means of preparing individual GOS platelets with high throughput, potentially expanding the applicability of nanographene oxide materials.     

自支撑三维功能化石墨烯/聚苯胺电极材料的制备及超级电容性能

采用水热法制备了三维石墨烯(3D-G),并以十八胺(ODA)为接枝剂对部分还原的氧化石墨烯进行氨基化处理,再利用原位聚合法在氨基化石墨烯表面生长聚苯胺,制备了十八胺功能化石墨烯/聚苯胺(G-ODA/PANI).对材料进行了结构表征、电化学性能分析和材料结构的比电容贡献分析.结果显示,电极材料的电容贡献大部分体现为材料的表面电容,G-ODA/PANI电极片在1 A/g电流密度时的比电容最高可达1080 F/g,是未功能化石墨烯/聚苯胺电极材料(G/PANI)的2.57倍,且循环稳定性也有很大的提高,循环10000周后的比容量保持率为90.8%,比G/PANI高9.6%.     

Self-assembled reduced graphene oxide/sulfur composite encapsulated by polyaniline for enhanced electrochemistry performance

Reduced graphene oxide/sulfur/polyaniline (referred to RGO/S/PANI) composite was self-assembled through in situ synthesis and used to investigate the electrochemical properties of lithium/sulfur cells. The RGO/S/PANI composite possessed 809.3/801.9 mAh g^?1 of initial charge/discharge capacities, higher than 588.3/588.2 mAh g^?1 for reduced graphene oxide/sulfur (referred to RGO/S) and 681.4/669.9 mAh g^?1 for sulfur/polyaniline (referred to S/PANI) at similar conditions. The RGO/S/PANI composite obtained 400 mAh g^?1 at 2 C and good reversible capacities of 605.5 and 600.8 mAh g^?1 at 100th charge/discharge cycle at 0.1 C, in comparison with low electrochemical performance of RGO/S and S/PANI. The improved properties could be attributed to the collaboration of RGO and PANI. Co-generation of RGO and sulfur acted as seeds for their depositions, stimulated their uniform distributions, and restricted the agglomeration of sulfur particles in situ synthesis. Polyaniline coated RGO/S and stabilized the nanostructure of RGO/S/PANI in repeated charge/discharge cycles. In addition, RGO and PANI provided many electron channels to enhance sulfur conductivity and sufficient void space for sulfur swelling during charge/discharge cycles.