Preparation of Hollow Polyaniline Micro/Nanospheres and Their Removal Capacity of Cr (VI) from Wastewater

The hollow polyaniline (PANI) micro/nanospheres are obtained through a simple monomer polymerization in alkaline solution with Triton X-100 Micelles as soft templates. The hollow PANI micro/nanospheres demonstrate rapid and effective removal ability for Chromium (VI) (Cr (VI)) in a wide pH range, and the maximum removal capacity can reach 127.88 mg/g at pH 3. After treated with acid, the used hollow PANI micro/nanospheres have about the similar removal capacity of Cr (VI) from wastewater.     

Synthesis,characterization, and evaluation of unsupported porous NiS submicrometer spheres as a cathode material for lithium batteries

Synthesis of a nanostructured pure phase nickel sulfide in a single step is a challenge. In this work, a new method for direct synthesis of uniform NiS–SiO₂ submicrospheres was developed by ultrasonic spray pyrolysis. Colloidal silica was used as a sacrificial template to create the porous structure. After silica removal, hollow, porous pure phase NiS nanospheres were obtained. The product was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy, and N₂ adsorption/desorption isotherm. The results confirmed the formation of single phase millerite NiS porous nanospheres with a high surface area of 312 m² g^?1. The NiS spheres were tested as cathode for lithium batteries. A discharge capacity of 340 mAh g^?1 with good capacity retention during multiple cycles was obtained.     

Facile synthesis of graphene/polyaniline composite hydrogel for high-performance supercapacitor

The graphene/polyaniline (PANI) composite hydrogel was successfully prepared by a one-step hydrothermal method. The morphology and structure of the sample were characterized by digital camera, scanning electron microscopy, and Fourier transform infrared spectroscopy spectra. By combining the advantages of high conductivity of graphene and high pseudocapacitance of PANI, the composite hydrogel was taken as supercapacitor electrode material. Cyclic voltammetry and galvanostatic charge/discharge experimental results show that the composite has excellent electrochemical performance. The specific capacitance value is 258.5 F g^?1 at a scan rate of 2 mV s^?1 and the specific capacitance value is up to 307 F g^?1 at a current density of 0.2 A g^?1. The specific capacitance value can still maintain 90 % of the initial value after repeating the galvanostatic charge–discharge for 1000 cycles at a current density of 1.0 A g^?1 showing good cycle stability.     

A new route to synthesize polyaniline-grafted carboxyl-functionalized graphene composite materials with excellent electrochemical performance

A new route to synthesize polyaniline (PANI)-grafted carboxyl-functionalized graphene (PGCG) composite material is established. In this paper, PGCG is first prepared through a two-step carboxyl-functionalized process. PANI can be grafted and grown on the surface of graphene due to the covalent bonding existing between the carboxyl-functionalized graphene and polyaniline. This method cannot only improve the mechanical performance and adaptive performance of polyaniline effectively, but also reduce the production costs and environmental pollution during the synthetic process. Therefore, a green and industrial synthetic process is achieved. X-ray diffraction (XRD) patterns, X-ray photoelectron spectroscopy (XPS) and Fourier transformed infrared (FTIR) all confirm that composite materials have been prepared successfully. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicate that the as-prepared PGCG has regular structure. Thermogravimetric analysis (TGA) indicates that the addition of graphene nanosheets can significantly improve the thermostability of PANI. Moreover, the as-prepared material exhibits superior electrochemical performance. As an electrode material for supercapacitors, PGCG possesses high specific capacitance of 158 F g^?1 at a scan rate of 25 mV s^?1 and 147 F g^?1 at 50 mV s^?1 in 1 M H₂SO₄. The Nyquist plot also confirms that the PGCG has low charge transfer resistance and good capacitive behavior. These great properties make PGCG a novel electrode material with potential applications in high-performance energy storage devices.     

Preparation and capacitance performance of polyaniline/titanium nitride nanotube hybrid

A polyaniline/titanium nitride (PANI/TiN) nanotube hybrid was prepared and used for an electrochemical supercapacitor application. Firstly, the well-aligned TiN nanotube array was prepared by anodization of titanium foil and subsequent nitridation through ammonia annealing. Then, PANI was deposited into TiN nanotube through the electrochemical polymerization process. The obtained PANI/TiN nanotube hybrid had an ordered porous structure. A high specific capacitance of 1,066 F g^?1 was obtained at the charge–discharge current density of 1 A g^?1 when only the mass of PANI was considered. The specific capacitance can even achieve 864 F g^?1 at 10 A g^?1 and still keep 93 % of the initial capacity after 200 cycles. An aqueous supercapacitor, consisting of two symmetric PANI/TiN nanotube hybrid electrodes and 1.0 M H₂SO₄ electrolyte solution, showed the specific capacitance of 194.8 F g^?1, energy density of 9.74 Wh kg^?1, and power density of 0.3 kW kg^?1.     

Synthesis of bimodal mesoporous carbon nanospheres for methyl orange adsorption

Mesoporous materials with bimodal mesopores show advantages in adsorption, energy storage, and catalysis because such unique structures are beneficial to the mass transfer. Here, we describe the synthesis of bimodal mesoporous carbon nanospheres (BMCSs) by using phenolic resin as carbon precursor, triblock copolymer Pluronic F127 as the soft template, and mesoporous silica spheres as hard templates. The BMCSs with uniform spherical morphology, high specific surface area (1489 m² g^??1), large pore volume (0.92 cm³ g^??1), and bimodal mesoporous structure (3.8 and 6.8 nm) exhibit promising properties for adsorption of methyl orange (MO). The maximum adsorption capacity of the BMCSs is 5.5?×?10² ± 0.2?×?10² mg g^??1, which is higher than that of many adsorbents reported. The kinetics studies show a better fit of pseudo-second-order model. Meanwhile, fitting equilibrium data show that the Langmuir model is more suitable to describe the MO adsorption than Freundlich model.     

The unique morphology role of thorn surface in determining electrochemical performance of polyaniline nano‐fibers via one‐step method

Polyaniline nano‐fibers with thorn surface morphology (T‐PANI) were synthesized by one‐step polymerization with adding additional aniline at later stage of chemical oxidation synthesis. In order to investigate the morphology role in determining electrochemical performance, the nano‐fibers PANI without thorn (PANI) was synthesized by the same polymerization process but at different time to add additional aniline. Material structures were characterized by field emission scanning electron microscope and Brunauer‐Emmett‐Teller method, and electrochemical performance was tested through cyclic voltammograms, galvanostatic charge‐discharge and electrochemical impedance spectroscopy. The data showed that the specific capacitance of T‐PANI was 443 F g^?1 at 5 mA cm^?2, which was much more than that of PANI (338 F g^?1 at 5 mA cm^?2). The solution resistance, charge transfer resistance, and diffuse resistance of T‐PANI were also lower than these of PANI. The results indicate that the thorn surface structure plays an important role in determining the electrochemical performance of polyaniline, which attribute to the improvements in pore size, pore distribution, special surface area, and conductivity. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42266.     

Electrically conductive polyaniline/polyimide microfiber membrane prepared via a combination of solution blowing and subsequent in situ polymerization growth

Dodecylbenzene sulfonic acid (DBSA) doped-polyaniline (PANI) coated conductive polyimide (PI) microfiber membrane was prepared by chemical oxidation polymerization. PI nanofiber membrane was prepared by solution blowing. Fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) proved that the successful preparation of composite microfiber membrane with core-shell structures. At the same time, the PANI had an effect of protection on PI nanofiber, which was detected by thermal gravimetric analysis (TGA). The orthogonal experiments were designed to determine the optimal reaction conditions for the conductivity of PANI/PI microfiber membranes as following: ANI concentration (0.15 mol L^?1), APS concentration (0.1 mol L^?1) and DBSA concentration (0.3 mol L^?1). The conductivity of PANI/PI microfiber membranes could arrive to 3.83 × 10^?2 S cm^?1. Moreover, the PANI/PI microfiber membranes had a superior hexavalent chromium (Cr (VI)) adsorption performance. The factors affecting the performance of hexavalent chromium (Cr (VI)) removal from the aqueous solutions were investigated.     

Enhanced performance by polyaniline/tailored carbon nanotubes composite as supercapacitor electrode material

Polyaniline/tailored carbon nanotubes composite (PANI/TCN) synthesized via situ polymerization of aniline monomer in the presence of tailored carbon nanotubes (TCN) is reported as electrode material for supercapacitors. The morphology, structure, and thermostability of the composite were characterized by scanning electron microscope, Fourier transform infrared, and thermogravimetric analysis. The electrochemical property of the resulting material was systematically studied using cyclic voltammetry and galvanostatic charge–discharge. The results show that the short rod‐like PANI dispersed well in the TCN with three‐dimensional network structure. The as‐prepared composite shows high specific capacitance and good cycling stability. A specific capacitance of 373.5 F g^?1 at a current density of 0.5 A g^?1 was achieved, which is much higher than that of pure PANI (324 F g^?1). Meanwhile, the composite retains 61.7% capacity after 1000 cycles at a scan rate of 50 mV s^?1. The enhanced specific capacitance and capacity retention indicates the potential of composite as a promising supercapacitor electrode material. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39971.     

In situ doping of PANI nanocomposites by gold nanoparticles for high‐performance electrochemical energy storage

Polyaniline (PANI) in situ doped with gold nanoparticles (Au/PANI) is synthesized by oxidative polymerization as electrode material for supercapacitor. The morphologies and structure of the obtained products are characterized by transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy; and electrochemical behaviors were measured by electrochemical workstation. The results show that the nanocomposites of Au/PANI are fabricated with gold nanoparticles (nano‐Au) dispersed well in PANI bulk; and specific capacitance (SC) and rate ability of Au/PANI are improved compared to the pristine PANI due to the introduction of nano‐Au. With nano‐Au content increasing, SC first increase and then decrease and the maximum SC of Au/PANI nanocomposite is up to 462 F g^?1 with the nano‐Au content of 1.64 wt %. Finally, both asymmetric and symmetric supercapacitor devices are assembled, exhibiting high energy densities of 8.95 and 4.17 Wh kg^?1, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45309.     

Highly Conductive Cellulose Network/Polyaniline Composites Prepared by Wood Fractionation and In Situ Polymerization of Aniline

Highly conductive cellulose network/polyaniline (PANI) composites are successfully formed using chemical fractionation of solid wood followed by in situ polymerization of aniline monomers in the purified wood. The increased porosity of the wood caused by the fractionation process enables the uniform deposition of PANI particles in the microstructure of the material, resulting in a high electrical conductivity of up to 36.79 S cm^?1, and a high weight gain rate of up to 143%. The interaction between PANI and the cellulose microfibril network leads to a decreased crystallinity of the composites. The electrode prepared from the cellulose network/PANI composites exhibits promising gravimetric specific capacitances of up to 218.75 F g^?1 and areal specific capacitances of up to 0.41 F cm^?2, and it can be assembled into all‐solid‐state supercapacitors with favorable energy storage performance, which may be attributed to the larger surface area, higher PANI content of the electrode, and the positive effect of the cellular structure of the cellulose network on electron transport. The present process can preserve the naturally hierarchical structure of wood and impart a promising conductivity to the composites, and it provides a promising way to produce hierarchical biomass‐based electronic materials for high‐performance storage field.     

Carbon nanotubes/amorphous carbon composites as high-power negative electrodes in lithium ion capacitors

A nitrogen-rich carbon nanotubes/amorphous carbon (CNT/C) composite was prepared by carbonising a CNT/polyaniline (PANI) composite, and characterised. Scanning electron microscopy and X-ray photoelectron spectroscopy confirmed that the composite retained a mesoporous CNT structure as its backbone, whilst the nitrogen-rich PANI-derived carbon formed a thin amorphous coating on the CNT surface. Electrochemical characterisation of the CNT/C composite indicated that it had nearly double the reversible Li⁺ intercalation capacity (390 vs. 219 mAh g^?1) and 39 % less irreversible capacity (622 vs. 1,015 mAh g^?1) than the pristine CNT. The CNT/C composite showed exceptionally high rate capability with a de-intercalation capacity of 81 mAh g^?1 at a very high charge/discharge rate of 60 C (time taken for charge or discharge is 1 min) (1 C = 1 h charge or discharge), whereas the pristine CNT delivered 53 mAh g^?1 at this C-rate. By comparison, the rate capabilities of conventional graphite (N3 and SLP30) were very poor above 5 C (~17 mAh g^?1 at 5 C). Both the pristine CNT and CNT/C composite showed an excellent cyclability at 1 C charge/discharge over 600 cycles. The CNT/C composite maintained a fairly stable capacity of ~200 mAh g^?1 after 600 cycles, whilst the commercial graphite showed a steady and significant decrease in de-intercalation capacity; reaching <70 mAh g^?1 after 600 cycles.     

Graphene/Polyaniline Aerogel with Superelasticity and High Capacitance as Highly Compression-Tolerant Supercapacitor Electrode

Superelastic graphene aerogel with ultra-high compressibility shows promising potential for compression-tolerant supercapacitor electrode. However, its specific capacitance is too low to meet the practical application. Herein, we deposited polyaniline (PANI) into the superelastic graphene aerogel to improve the capacitance while maintaining the superelasticity. Graphene/PANI aerogel with optimized PANI mass content of 63 wt% shows the improved specific capacitance of 713 F g^?1 in the three-electrode system. And the graphene/PANI aerogel presents a high recoverable compressive strain of 90% due to the strong interaction between PANI and graphene. The all-solid-state supercapacitors were assembled to demonstrate the compression-tolerant ability of graphene/PANI electrodes. The gravimetric capacitance of graphene/PANI electrodes reaches 424 F g^?1 and retains 96% even at 90% compressive strain. And a volumetric capacitance of 65.5 F cm^?3 is achieved, which is much higher than that of other compressible composite electrodes. Furthermore, several compressible supercapacitors can be integrated and connected in series to enhance the overall output voltage, suggesting the potential to meet the practical application.     

Facile synthesis of NiO/MWCNT composites by a vacuum solution infiltration method for lithium-ion batteries

Nickel oxide/multi-walled carbon nanotube (NiO/MWCNT) composites were fabricated via a vacuum solution infiltration method combined with a calcination treatment. The crystalline structure and morphology were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) with selected area electron diffraction (SAED). The specific surface area, pore size, and pore volume were obtained by Brunauer–Emmett–Teller (BET). The as-prepared NiO/MWCNT composites deliver an initial discharge capacity of 1,015 mAh g^?1 with 86 % capacity retention (873 mAh g^?1) after 50 cycles at a current rate of 0.1 C. The enhanced electrochemical performance is ascribed to the nanosized NiO and MWCNTs which can act as buffering matrix to relax the volume expansion and electron transfer conductor in the composites.     

In situ synthesis of cabbage like polyaniline@hydroquinone nanocomposites and electrochemical capacitance investigations

A Cabbage like polyaniline@hydroquinone composite microsphere was synthesized using in situ polymerization and the electrochemical performance was investigated. The core template, p‐benzoquinone, is demonstrated working as an oxidizing agent for the in situ polymerization of PANI, and to be reduced to 1, 4‐hydroquinone after reaction. The morphology and microstructure of samples were examined by field emission scanning electron microscopy, transmission electron microscope, X‐ray photoelectron spectrometer, thermo gravimetric, and Fourier transform infrared spectra. The cyclic voltammetry, impedance and galvanostatic charge/discharge analysis demonstrates that PANI contributes electronic conductive channels for hydroquinone, and hydroquinone works as a pseudocapacitance component. The prepared PANI@hydroquinone nanocomposite exhibits brilliant electrochemical properties of a specific capacitance of 126.0 F g^?1 at a scan rate of 5 mV s^?1 and enhanced stability of about 85.1% of initial capacitance retained after 500 cycles scanning at a current density of 1 A g^?1. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42290.     

Synthesis of hollow porous carbon nanospheres from coal tar for adsorption of Direct Black 38 dye

A hollow porous carbon nanospheres (HPCNs) material which suits for adsorption of Direct Black 38 (DB38) was prepared from coal tar using zinc acetate as a template coupled with KOH activation. The synthesized HPCNs features with nanospheres structure and contains both micropores and a lot of mesopores. The HPCN_1?4?2 made with the mass weight ratio of coal tar/zinc acetate/KOH at 1:4:2 shows a large surface area of 1374 m² g^?1 with an average pore size of 7.41 nm. The HPCN_1?4?2 exhibits excellent adsorption capacity for DB38 dye, which has big molecular size at room temperature. This is mainly due to its large surface area and pore volumes contributed by its mesopores. This work suggests an effective way to synthesize a high performance adsorbent for large molecular size dyes from low-cost coal tar.     

Hydrothermally synthesized FeCo2O4 nanostructures: Structural manipulation for high-performance all solid-state supercapacitors

The exploration of high performance supercapacitors has received emerging the worldwide research interests in satisfying the gradually increased energy consumption. In this paper, we adopt a facile hydrothermal strategy to synthesize ternary FeCo₂O₄ directly on nickel foam. A series of structure such as nanowires, nanoflake@nanowire hetero-structure and hierarchical nanospheres have been achieved via modulating the synthetic time. The morphology and structure of the as-prepared samples are characterized by using scanning electron microscopy and X-ray diffraction spectroscopy. The relationship between the detail processing parameters and electrochemical performance are also revealed by cyclic voltammetry, galvanostatic charge-discharge measurements, cycle stability tests and electrochemical impedance spectroscopy. Notably, the as-prepared nanoflake@nanowire hetero-structure exhibits a high specific capacitance of about 969 F g^?1 at 2 A g^?1 in alkaline aqueous solution and a remarkable cycling stability (91% capacity retention after 2000 cycles). The excellent supercapacitors performance of nanoflake@nanowire hetero-structure can be attributed to the high conductivity, large active area as well as robust architectures that derive from structural synergetic effects. Furthermore, a symmetric all solid-state supercapacitor has been fabricated by using nanoflake@nanowire hetero-structure as both the anode and cathode electrodes. The as-fabricated supercapacitor delivers excellent electrochemical performance. It's anticipated that FeCo₂O₄ would be a promising material for electrochemical energy storage applications.     

Mesoporous TiO<Subscript>2</Subscript> microspheres synthesized via a facile hydrothermal method for dye sensitized solar cell applications

Mesoporous TiO₂ microspheres were successfully synthesized by a facile hydrothermal process and the obtained product was sintered at 450 °C. The sintered TiO₂ powder was characterised by powder X-ray diffraction pattern and the result shows pure anatase phase with good crystalline nature. The morphological image of field emission scanning electron microscopy and high resolution transmission electron microscopy shows spherical shape and size of the particles is around 100 to 300 nm. The Brunauer–Emmett–Teller surface area of synthesized TiO₂ material was 56.32 m² g^?1 and average pore width of synthesized materials was 7.1 and 9.3 nm. Bimodal pore structure of TiO₂ microspheres has been very effective for electrolyte diffusion into photoanode in dye sensitized solar cells. The synthesized anatase TiO₂ microsphere based dye sensitized solar cells have high surface area with light scattering effect to enhance the photocurrent and conversion efficiency than the commercial P25 photoanode material. The power conversion efficiency of synthesized mesoporous TiO₂ microspheres and commercial P25 material is 4.2 and 2.7 % respectively. Therefore bimodal mesoporous anatase TiO₂ microsphere appears to be a promising and potential candidate for dye sensitized solar cells (DSSC) application.     

Synthesis and characterization of monodisperse hollow SnO<Subscript>2</Subscript> microspheres and their enhanced sensing properties to ethanol

The monodisperse hollow SnO₂ (H-SnO₂) microspheres were successfully synthesized by the ion exchange method using sulfonated PS microspheres as a template. The structure and morphology were characterized by X-ray diffraction, transmission electron microscopy and high-resolution transmission electron microscopy, which confirms the hollow structure of the products. The H-SnO₂ microspheres are composed of numerous SnO₂ nanoparticles with a shell thickness of about 13 nm. The monodisperse H-SnO₂ microspheres have a high specific surface area of 55.54 m²/g, which improves the gas sensing properties toward ethanol. Gas-sensing measurement results indicate that H-SnO₂ microspheres exhibit an excellent sensitivity (103.1) toward 200 ppm ethanol at 260 °C, which is much higher than that (65.8) of SnO₂ nanoparticles.     

Facile Fabrication of Uniform Polyaniline Nanotubes with Tubular Aluminosilicates as Templates

The uniform polyaniline (PANI) nanotubes, with inner diameter, outer diameter, and tubular thickness of 40, 60, and 10 nm, respectively, were prepared successfully by using natural tubular aluminosilicates as templates. The halloysite nanotubes were coated with PANI via the in situ chemical oxidation polymerization. Then the templates were etched with HCl/HF solution. The PANI nanotubes were characterized using FTIR, X-ray diffraction, and transmission electron microscopy. The conductivity of the PANI nanotubes was found to be 1.752 × 10⁻⁵ (Ω·cm)⁻¹.