Polyaniline/single-walled Carbon Nanotubes Research Articles

Composite Aerogel of Electropolymerized Polyaniline and SWCNTs with High Thermoelectric Performance

AbstractAerogels are promising in the preparation of high‐performance thermoelectric (TE) materials due to their ultralow thermal conductivity. However, the TE performance of aerogels remains unsatisfactory. Herein, polyaniline/single‐walled carbon nanotubes (PANI/SWCNT) composite aerogel with high thermoelectric performance is synthesized through dynamic three‐phase interfacial electrochemical polymerization of aniline and subsequent physical mixing of PANI with SWCNTs followed by liquid nitrogen quenching and freeze‐drying. By adjusting the content of SWCNTs, the PANI/SWCNT aerogel (50 wt% SWCNTs) achieves a high power factor (PF) of 73.33 ± 2.03 µW m−1 K−2. The ultralow thermal conductivity of around 2.30 × 10−2 W m−1 K−1 for the composite aerogel is superior to that of most conventional organic TE materials, rendering an excellent figure of merit (ZT) value of ≈0.95 at room temperature and great potential in improving TE performance of organic and organic/inorganic composites. Thermal treatment of the composite aerogel further enhances the PF to 96.28 ± 1.89 µW m−1 K−2. This work provides an effective method in the formation of PANI/SWCNT TE composites and it puts forward insights into the preparation of other high‐performance TE composites.

Engineering Active Sites of Polyaniline for AlCl2 + Storage in an Aluminum-Ion Battery.

The reversible capacity of AlCl4 - intercalation/de-intercalation in conventional cathodes of aluminum-ion batteries (AIBs) is difficult to improve due to the large size of AlCl4 - anions. Therefore, it is highly desirable to realize the intercalation/de-intercalation of smaller Al-based ions. Here, we fabricated polyaniline/single-walled carbon nanotubes (PANI/SWCNTs) composite films and protonated the PANI nanorods. The protonation endows PANI with more active sites and enhanced conductivity. Hyper self-protonated PANI (PANI(H+ )) exhibits reversible AlCl2 + intercalation/de-intercalation during the discharge/charge process. As a result, the discharge capacity of the Al/PANI(H+ ) battery is twice as high as that of the initial composite films. PANI(H+ )@SWCNT electrodes also have a stable cycling life with only 0.003 % capacity decay per cycle over 8000 cycles. Owing to the excellent mechanical properties, PANI(H+ )@SWCNT composite films can act as the electrodes of flexible AIBs.

Engineering Active Sites of Polyaniline for AlCl2+ Storage in an Aluminum‐Ion Battery

AbstractThe reversible capacity of AlCl4− intercalation/de‐intercalation in conventional cathodes of aluminum‐ion batteries (AIBs) is difficult to improve due to the large size of AlCl4− anions. Therefore, it is highly desirable to realize the intercalation/de‐intercalation of smaller Al‐based ions. Here, we fabricated polyaniline/single‐walled carbon nanotubes (PANI/SWCNTs) composite films and protonated the PANI nanorods. The protonation endows PANI with more active sites and enhanced conductivity. Hyper self‐protonated PANI (PANI(H+)) exhibits reversible AlCl2+ intercalation/de‐intercalation during the discharge/charge process. As a result, the discharge capacity of the Al/PANI(H+) battery is twice as high as that of the initial composite films. PANI(H+)@SWCNT electrodes also have a stable cycling life with only 0.003 % capacity decay per cycle over 8000 cycles. Owing to the excellent mechanical properties, PANI(H+)@SWCNT composite films can act as the electrodes of flexible AIBs.

Covalently bonded polyaniline-reduced graphene oxide/single-walled carbon nanotubes nanocomposites: influence of various dimensional carbon nanostructures on the electrochromic behavior of PANI

In this paper, water-dispersible and covalently bonded polyaniline-carbon nanostructures, including polyaniline-reduced graphene oxide (PANI-rGO), polyaniline-single-walled carbon nanotubes (PANI-SWCNTs), and polyaniline-reduced graphene oxide/single-walled carbon nanotube (PANI-rGO/SWCNTs) nanocomposites, were synthesized by grafting PANI onto p-phenylenediamine (PPD)-functionalized graphene oxide (GO) or single-walled carbon nanotubes (SWCNTs) using polystyrene sulfonate (PSS) as a macromolecular dopant agent. The structures and morphologies of the PANI, PANI-rGO, PANI-SWCNTs, and PANI-rGO/SWCNTs nanocomposites were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The cyclic voltammetry and UV–vis spectra were performed on an electrochemical workstation and a UV–vis spectrometer, respectively. The results show that the electrochromic and electrochemical properties of nanocomposites can benefit from the high conductivity of SWCNTs and the abundant active sites of rGO. When SWCNTs and rGO work together, their respective shortcomings are overcome, allowing the nanocomposite to exhibit the best electrochemical and electrochromic properties. The optical contrast increased from 0.38 for PANI to 0.52 for PANI-rGO/SWCNTs. The coloring and bleaching times decreased from 2.59 s and 2.39 s, respectively, for PANI to 1.33 and 0.78 s, respectively, for PANI-rGO/SWCNTs. The charge transfer resistance (Rct) decreased from 135 Ω for PANI to 30 Ω for PANI-rGO/SWCNTs. The synergistic effect of PANI, rGO, and SWCNTs can significantly improve the electrochromic ability of PANI. Electrochromic properties of covalently bonded polyaniline-reduced graphene oxide/single walled carbon nanotubes nanocomposites. A high performance electrochromic material was prepared using polyaniline (PANI) and two different dimensional carbon nanostructures, single-walled carbon nanotubes (SWCNTs) and reduced graphene oxide (rGO) as the components. The covalent bond was introduced to interface between PANI and two carbon nanostructures to form a three-dimensional conductive network. Owing to the high electron conduction through directly connected covalent bond and loose molecular chain aggregation brought by two various dimensional carbon nanostructure, PANI-rGO/SWCNTs nanocomposites exhibit superior electrochemical and electrochromic properties (high optical contrast and short switching time) compared with PANI.

Effect of different oxidants on polyaniline/single walled carbon nanotubes composites synthesized via ultrasonically initiated in-situ chemical polymerization

This study is aimed at investigating the effect of different oxidants on properties of polyaniline/single walled carbon nanotubes (PANI/SWCNT) composites and scrutinizing a suitable oxidant to improve the properties of composites. PANI/SWCNT composites were fabricated via ultrasonically initiated in-situ chemical polymerization technique using four different oxidants; hydrogen peroxide (H2O2), ammonium peroxidisulphate ((NH4)2S2O8), potassium dichromate (K2Cr2O7) and potassium iodate (KIO3). Percent yield (97%), molecular weight (45532 g mol−1) and electrical conductivity (0.835 S cm−1) were found maximum for composite prepared in the presence of H2O2. Structural confirmation of PANI and charge transfer complex formation between PANI and SWCNT were confirmed by fourier transform infrared spectroscopy, UV–visible spectroscopy and X-ray diffraction spectroscopy. Thermogravimetric analysis verified that the PANI/SWCNT composite synthesized using H2O2 had maximum thermal stability with least thermal degradation (∼28%). Minimal thermal transitions of the composite were also observed for same composite by differential scanning calorimetry. Scanning electron microscopic images of PANI/SWCNT composites revealed that SWCNT were properly dispersed in PANI matrix when H2O2 was used. Above results provide the valuable suggestion that; H2O2 is a promising oxidant to enhance structural, thermal, electrical and microscopic properties of composites.

Titanium doped niobium oxide for stable pseudocapacitive lithium ion storage and its application in 3 V non-aqueous supercapacitors

Developing high energy density supercapacitors is of great importance to the transportation, consumer electronics and micro-grid energy storage sectors. We introduce a new electrode combination with titanium-doped orthorhombic phase niobium oxide and polyaniline-single wall carbon nanotubes. The organic electrolyte based supercapacitor achieves an energy density over 110.3 Wh kg−1 at 150 W kg−1.

Electrochemical sensor based on polyaniline nanofibers/single wall carbon nanotubes composite for detection of malathion

Detection of malathion (organophosphorous pesticide) based on composite of polyaniline nanofiber and single walled carbon nanotube deposited onto graphite electrode was investigated. >Fourier transforms infrared and UV–vis absorption spectra, X-ray diffraction, scanning electron microscope and cyclic voltammetry were used to characterize the prepared polyaniline. Malathion concentration was detected using differential pulse voltammetry technique at polyaniline–single wall carbon nanotubes modified graphite electrode. The fabricated polyaniline–single wall carbon nanotubes modified graphite electrodes have exhibited higher accuracy toward the reduction of malathion. Malathion was found to exhibit one well-defined reduction peak at pH 7. A linear response to malathion in the concentration range from 2.0×10−7M to 14.0×10−7M was observed. The minimum detection limit in the linear range for the modified electrodes was 2.0×10−7M malathion. It was found that the single wall carbon nanotubes improved the sensitivity of the polyaniline salt graphite electrode from 5.4mA/μM for polyaniline salt to 7.22mA/μM.

Solid-State Synthesis of Polyaniline/Single-Walled Carbon Nanotubes: A Comparative Study with Polyaniline/Multi-Walled Carbon Nanotubes

The polyaniline/single-walled carbon nanotubes (PANI/SWNTs) composites with a content of SWNTs varying from 8 wt% to 32 wt% were synthesized using a solid-state synthesis method. The structure and morphology of the samples were characterized by fourier transform infrared (FTIR) spectra, ultraviolet-visible (UV-vis) absorption spectra, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical performances of the composites were investigated by galvanostatic charge–discharge and cycling stability measurements. The structure and properties of PANI/SWNTs were compared with those of PANI/multi-walled carbon nanotubes (PANI/MWNTs) prepared under the same polymerization conditions. The results from FTIR and UV-vis spectra showed that the composites with SWNTs displayed a higher oxidation and doping degree than pure PANI, which is similar to that of PANI/MWNTs. The morphological studies revealed that PANI/SWNTs did not display any rod-like and granular-like features, which appeared in PANI/MWNTs. The galvanostatic charge–discharge measurements indicated that the specific capacitance of PANI/SWNTs is not higher than that of PANI/MWNTs, but the PANI/SWNTs exhibited higher cycling stability and more stable electrochemical behavior in neutral and alkaline electrolytes than PANI/MWNTs.

Fabrication of Polyaniline/Carbon Nanotubes Composites Using Carbon Nanotubes Films Obtained by Electrophoretic Deposition

In this study, we report a facile electrochemical method to obtain polyaniline/single-wall carbon nanotubes (PANI/SWCNTs) composite electrodes by combining the electroreduction of diazonium salts and electropolymerization of conductive polymers. In a first step, the SWCNTs are covalently functionalized with diphenyl amine through the electrochemical reduction of the 4-aminodiphenylamine diazonium salt in order to provide anchors for the subsequent polymer electrodepostion. The aniline oxidation remains possible on this grafted layer and PANI can easily be deposited on the diphenyl amine-modified electrodes. The electrochemically deposited PANI/SWCNTs composites exhibit excellent electrochemical charge storage properties making them promising electrode materials for high power supercapacitors.

Charge‐transfer behavior of polyaniline single wall carbon nanotubes nanocomposites monitored by resonance Raman spectroscopy

AbstractHighly dispersed nanocomposites of polyaniline(PANI) and oxidized single wall carbon nanotubes(SWNTs) have been prepared using dodecylbenzenesulfonic acid as dispersant. The materials were characterized via resonance Raman and electronic absorption spectroscopies. The behavior of the composites as a function of the applied potential was also investigated using in situ Raman electrochemical measurements. The results obtained at Elaser = 1.17 eV suggest that a charge‐transfer process occur between PANI and semiconducting nanotubes for samples where the metallic tubes are previously oxidized. The spectroelectrochemical data show that the presence of SWNTs prevents the oxidation of PANI rings. Copyright © 2010 John Wiley & Sons, Ltd.