Polyaniline Sheets Research Articles

Preparation of Two-Dimensional Polyaniline Sheets with High Crystallinity via Surfactant Interface Self-Assembly and Their Encryption Application.

In recent years in the field of traditional materials, traditional polyaniline has faced a number of scientific problems such as an irregular morphology, high difficulty in crystallization, and difficulty in forming an ordered structure compared to the corresponding inorganic materials. In response to these urgent issues, this study determines how to prepare a highly ordered structure in polyaniline formed at the gas-liquid interface. By dynamically arranging aniline monomers into a highly ordered structure with sodium dodecyl benzene sulfonate (SDBS) surfactant, aniline polymerization is initiated at the gas-liquid interface, resulting in two-dimensional polyaniline crystal sheets with a highly ordered structure. By elucidating the microstructure, crystallization process, and molecular structure of the two-dimensional polyaniline crystal sheets, the practical application of polyaniline as an encryption label in the field of electrochromism has been further expanded, thus making polyaniline widely used in the field of information encryption. Therefore, the synthesis of flaky polyaniline crystal sheets has a role in scientific research and practical application, which will arouse the interest and exploration of researchers.

Inkjet printing of 2D polyaniline for fabricating flexible and patterned electrochromic devices

Conjugated organic polymer (COP)-based electrochromic devices (ECDs) exhibit promising applications in digital and color displays. However, fabricating COP-based ECDs integrated with excellent electrochromic performance, customized patterns, and flexibility remains challenging. In this study, we report inkjet-printed, flexible, and patterned ECDs based on two-dimensional (2D) polyaniline (PANI) sheets, which are evenly dispersed in formic acid (FA) enabling high-precision, stable inkjet printing. The pristine lamellar structure of PANI sheets, which combine nanoscale thickness and an appropriate doping ratio, and the additive-free ink composition endow the printed PANI electrodes and ECDs with high performance. The fabricated PANI electrode exhibits a high optical contrast (76% at a wavelength of 750 nm), a good coloration efficiency (CE) of 259.1 cm2 C−1, and a short coloration/bleaching time (1.8/2.4 s), simultaneously integrated with pseudocapacitance and mechanical flexibility. Moreover, the 2D lamellar PANI ink developed in this study can be printed into various designed patterns, particularly for electrochemically controlled, addressable electrochromic displays. This work highlights 2D lamellar PANI as a promising electrochromic material for flexible and patterned ECDs.

Synergistic effect of reduced graphene oxide layers wrapped in polyaniline sheets to porous blades for boosted oxygen evolution reaction

Electrochemical water splitting is a unique approach for producing renewable energy in hydrogen fuel, though it is limited due to the sluggish kinetics of oxygen evolution reaction (OER). To enhance the efficacy of hydrogen production, it is a need to regulate oxygen evolution reaction. An efficient strategy is to construct a competent electrocatalyst with an immense open, active site, highly stable, porous structure, and large surface area. This study employs an inexpensive, facile, and eco-friendly single-step route to fabricate reduced graphene oxide (rGO) layers wrapped in polyaniline (PANI) sheets to achieve the controlled blades morphology. All the synthesized materials are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), BET to examine their structural, morphological, and textural properties. Interestingly, when all the synthesized materials are employed for electrochemical measurements, rGO/PANI nanocomposite exhibits exceptional performance with a low overpotential of 221 mV to achieve a current density of 10 mA/cm2, lower Tafel slope of 37 mV/dec, and also high stability of 20 h. Overall, this work could lead up to the fabrication of innovative blade structured nanocomposite as an efficient electrocatalyst and make it applicable for multiple applications.

Tuning the thermoelectric efficiency of a polyaniline sheet using strain engineering

Two-dimensional polyaniline monolayers (C3N) have been recently synthesized as indirect semiconductors with high electron mobility. We investigate the electrical and thermal properties of a C3N sheet using a combination of density functional theory and the Green function formalism. Tensile strain along a zigzag direction can drive the transition from an indirect to a direct semiconductor, whereas the sheet transitions from a semiconductor to a metal under compressive strain. The thermoelectric efficiency of an unstrained C3N sheet is higher in p-doping, and its maximum value is obtained when the transport is along the zigzag direction. A reduction in the figure of merit is found upon applying strain, independent of its direction. To overcome this reduction, we show that when the electrical transport and strain are perpendicular to each other, the thermoelectric efficiency of the C3N sheet can be significantly increased, depending on the type of strain (tensile or compression). The results support the potential application of C3N sheets in the thermoelectrics and optoelectronics industries through using strain engineering.

Semi-hydrogenated polyaniline sheet: A half-metal with exotic properties

Polyaniline sheet has been recently synthesized experimentally and attracted a lot of attention due to its exotic properties. In this research, we study electrical properties of semi-hydrogenated polyaniline sheet, SHP, in details. First-principle calculations reveal that the SHP is a half-metal with spin polarization of 100%. The magnetization is attributed to the localized pz electronic orbitals of unsaturated carbon atoms and half-metallicity is related to the nitrogen atoms. Phonon band structure confirms the sheet is dynamically stable and ab initio molecular dynamics simulations indicate the sheet can be synthesized at room temperature. Tensile biaxial strain improves the half-metallicity of the sheet so that a 70% increase in the band gap of spin-up is observed when a 12% tensile strain is applied. The substrate can moderate the magnetization of two-dimensional materials. Our analysis reveals the sheet grown on the hexagonal boron-nitride sheet is still a half-metal. A transition from half-metal to magnetic metal is observed when the sheet is grown on the Si(111) substrate due to strong bonds between some unsaturated carbon atoms with top Si atoms. In addition, we show that the sheet can preserve its half-metallicity under hydrogen vacancy. Our findings show that semi-hydrogenated polyaniline sheet has a great potential for spintronics and spin-filtering.

Polyaniline (C3N) nanoribbons: Magnetic metal, semiconductor, and half-metal

A two-dimensional polyaniline sheet has been recently synthesized and found that it is a semiconductor with an indirect band gap. Polyaniline nanoribbons decomposed from the two-dimensional polyaniline sheet (C3N sheet) are investigated using a density functional theory. The existence of nitrogen atoms in the edge of the ribbons increases the stability and magnetization of the ribbons and make them different from graphene nanoribbons. Unsaturated nanoribbons are magnetic metals so that the armchair C3N nanoribbons are gap-less spin semiconductors in the antiferromagnetic state and half-metals in the ferromagnetic state. A transition from a metal to semiconductor is observed in the armchair C3N nanoribbons when the edge atoms are passivated by hydrogen. The band gap of the hydrogen saturated armchair C3N nanoribbons can be controlled using an external transverse electric field so that its magnitude is dependent on the direction of the electric field. Being a metal or semiconductor in hydrogen saturated zigzag C3N nanoribbons is strongly dependent on the edge atoms so that just ribbons having nitrogen atoms in both edges are semiconductor. An external electric field cannot induce any spin polarization in the zigzag nanoribbons, which is in contrast with what was observed in zigzag graphene nanoribbons.

Electrical and mechanical properties of a fully hydrogenated two-dimensional polyaniline sheet

Two-dimensional (2D) polyaniline sheet has been recently synthesized and showed that it is a semiconductor with indirect band gap. In this research, we examine electrical and mechanical properties of a fully hydrogenated 2D polyaniline sheet C3NH using density functional theory. Results show that the C3NH sheet is an insulator with a band gap more than 5 eV. The sheet is quasi planner and dynamically stable confirmed by phonon band structure. Young modulus of the sheet is 275 N/m. Ab-initio molecular dynamics simulations show that the C3NH sheet can be stable at 1000 K indicating a high melting point. Tensile strain reduces the band gap of the sheet and electron effective mass. In return, hole effective mass is strongly dependent on the strain direction so that strain along zigzag (armchair) increases (reduces) hole effective mass. Our findings show that C3NH sheet is a promising candidate for electronic and optoelectronic applications and strain engineering can be used to tune its properties.

Synthesis of Villi-Structured Polyaniline Sheets Using Organic Single Crystal Surface-Induced Polymerization.

Villi-structured polyaniline sheets (VPASs) were synthesized by the organic single-crystal surface-induced polymerization (OCSP) method using sodium decanesulfonate as a template. Aniline hydrochloride is used as a monomer instead of aniline to improve the electrostatic interaction between monomers and hydrated crystals, which reveals that the mechanism of OCSP occurs from the electrostatic force between positively charged monomers and the negatively charged surface of hydrated crystals. Compared with conventional polyaniline (3.13 × 10–2 S/cm), VPASs showed higher electrical conductivity (1.07 × 10–1 S/cm). The thickness of double-layered VPASs is about 136 nm, and the surface of VPASs shows a random porous structure with a villi-like morphology. This morphological property provides a large surface area, which can be advantageous to various electrochemical applications. The process yields mass-producible inexpensive materials, and the products are suitable for flexible devices because of their characteristic morphology.

Multidimensional polyaniline structures from micellar templates

Polyaniline (PANI) multidimensional (MD) structures (i.e., flowers, sheets, and plates) are successfully synthesized by adjusting the dosage of cationic surfactant cetyltrimethylammonium chloride (CTAC) in the range of 0.050–0.50 g in static HCl solution (0.010 M) at room temperature without stirring. CTAC micellar templates consisting of quaternary ammonium cations and binary persulfate anions direct the fabrication of PANI MD structures. On the basis of the employment of CTAC, the effect of pH value on PANI morphologies is investigated in detail, and followed by the obtainment of other PANI structures, including nanobelts, net-like structures, and particulates. Among the PANI MD structures, PANI sheets in micron size have good dispersibility and excellent processability, which are due to the synergistic effect of PANI’s suitable size and appropriate CTAC molecules. The results and strategies presented here provide opportunities to obtain good water dispersibility to conduct polymer structures with big size.

A reduced graphene oxide/SnO2/polyaniline nanocomposite for the anode material of Li-ion batteries

In this study, a SnO2 based composite composed of SnO2 nanoparticles, reduced graphene oxide (rGO) and polyaniline (PANI) sheets was synthesized and evaluated as the anode material of high performance Li-ion batteries. The rGO/SnO2/PANI composite exhibited excellent electrochemical performance including high capacity (1017mAhg−1 at 200mAg−1 for the 2nd cycle), superior rate capability (397mAhg−1 at a current density of 10Ag−1) and cyclic stability (1280mAhg−1 after 200cycles). The significant enhancements in electrochemical performance are ascribed to the nanostructure of the composite in which SnO2 nanoparticles of around 3.9nm were most probably sandwiched between rGO and PANI sheets that are flexible and conductive. Extremely fine SnO2 nanoparticles, high specific surface area, mesoporous structure and good electrical conductivity of the composite resulted in the high capacity and superior rate performance. The nanostructure of rGO/SnO2/PANI can accommodate volume expansion during lithiation of SnO2 and at the same time inhibit particle aggregation during cycling, yielding excellent cyclic stability of the rGO/SnO2/PANI composite.

Development of polyaniline–lithium secondary battery

AbstractA series of coin‐type lithium secondary batteries with polyaniline positive electrodes was developed and commercialized which might be not only the first practical polymer battery but also the first industrial application of conducting polymers. Performances of the commercialized batteries were described in detail in this paper.In order to achieve the development the most important thing was the optimization of molecular structure and molphology of multiguise polyaniline as the electrode material. According to the findings obtained during the development, polyaniline sheet was prepared substantially to be composed of imino‐1,4‐phenylene (IP) and the cation radical of IP (IP+) by the novel procedure, not to include quinoid configuration of polyaniline (NP) which was proved to be electrochemically inactive in non‐aqueous systems.