Polyaniline TiO2 Research Articles

Empowering TiO2–coated PVDF membranes stability with polyaniline and polydopamine for synergistic separation and photocatalytic enhancement in dye wastewater purification

Photocatalytic membranes are effective in removing organic dyes, but their low UV resistance poses a challenge. To address this, self-protected photocatalytic PVDF membranes were developed using polyaniline (PANI) and polydopamine (PDA), whaich are anti-oxidation polymers, as interlayers between the membrane and TiO2. PVDF membranes were first modified by a self-polymerization layer of either PANI or PDA and then coated with titanium dioxide (TiO2). The TiO2 remained firmly attached to the PANI and PDA layer, regardless of sonication and prolonged usage. The PANI and PDA layers enhanced the durability of PVDF membrane under UV/TiO2 activation. After 72 h of irradiation, PVDF–PDA–TiO2 and PVDF–PANI–TiO2 membranes exhibited no significant change. This process improved both separation and photocatalytic activity in dye wastewater treatment. The PVDF–PDA–TiO2 and PVDF–PANI–TiO2 membranes showed enhanced membrane hydrophilicity, aiding in the rejection of organic pollutants and reducing fouling. The modified membranes exhibited a significant improvement in the flux recovery rate, attributed to the synergistic effects of high hydrophilicity and photocatalytic activity. Specially, the flux recovery rate increased from 17.7% (original PVDF) to 56.3% and 37.1% for the PVDF–PDA–TiO2 membrane and PVDF–PANI–TiO2 membrane. In dye rejection tests, the PVDF‒PDA‒TiO2 membrane achieved 88% efficiency, while the PVDF‒PANI‒TiO2 reached 95.7%. Additionally, the photodegradation of Reactive Red 239 (RR239) by these membranes further improved dye removal. Despite an 11% reduction in flux, the PVDF–PDA–TiO2 membrane demonstrated greater durability and longevity. The assistance of PANI and PDA in TiO2 coating also improved COD removal (from 33 to 58–68%) and provided self-protection for photocatalytic membranes, indicating that these photocatalytic membranes can contribute to more sustainable wastewater treatment processes.

Polyaniline–Titanium Dioxide Heterostructures as Efficient Photocatalysts: A Review

This review paper focuses on present issues concerning the use of polyaniline–TiO2 heterostructures as potentially efficient photocatalysts. Conducting polymers such as polyaniline (PANI) are used in the preparation of heterojunction systems with metal oxides like titania to overcome their inherent limitations, e.g., their sole absorption of UV light and overly fast recombination of charge carriers. This review discusses preparation methods, the properties of resultant products and mechanistic aspects. An important part of this paper is its presentation of the major challenges and future perspectives of such photocatalytic materials.

Highly Sensitive and Selective Sol-Gel Spin-Coated Composite TiO2–PANI Thin Films for EGFET-pH Sensor

A highly selective and sensitive EGFET-pH sensor based on composite TiO2-PANI had been developed in this work. A sol-gel titanium dioxide (TiO2) and the composite of TiO2 with semiconducting polyaniline (PANI) were deposited using a simple spin-coating method on an indium tin oxide (ITO) substrate. The films have been explored as a sensing electrode (SE) of extended gate field-effect transistor (EGFET) for pH applications in the range of pH 2 to 12. The pH sensitivities between TiO2, TiO2-PANI bilayer composite, and TiO2-PANI composite thin films were discussed. Among these, the TiO2-PANI composite thin film showed a super-Nernstian behavior with high sensitivity of 66.1 mV/pH and linearity of 0.9931; good repeatability with a standard deviation of 0.49%; a low hysteresis value of 3 mV; and drift rates of 4.96, 5.54, and 3.32 mV/h in pH 4, 7, and 10, respectively, for 6 h. Upon applying the TiO2-PANI composite as the SE for nitrate measurement, low sensitivity of 12.9 mV/dec was obtained, indicating that this film is a highly selective sensing electrode as a pH sensor. The surface morphology and crystallinity of the thin films were also discussed.

Enhancing the Performance and Recyclability of Polyaniline/TiO2 Hybrid Nanocomposite by Immobilizing with Zein/Hydroxyethyl Cellulose Composites for Removal of Anionic Dyes

Fabrication of a stable, recyclable and eco-friendly photocatalyst for dye treatment is vital in sustaining a clean ecosystem. In this regard, polyaniline/TiO2 (PANI/TiO2) photocatalyst was immobilized by zein/hydroxyethyl cellulose (zein/HEC) adhesive to enhance recyclability and catalytic activity. The blending of zein/HEC/PANI/TiO2 photocatalyst involves in situ oxidative polymerization, followed by immobilization with zein/HEC functionalized composites. The PANI/TiO2 composite was successfully grafted with the adhesive through physicochemical interaction, as evidenced by field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffractometer (XRD). The simultaneous thermal analysis (STA) results show that the photocatalyst has the best thermal stability relative to PANI and PANI/TiO2 in the recommended range of dye degradation temperature. The effect of external factors like TiO2 nanoparticle proportion, pH of the solution and catalyst dosage was studied in response to dye degradation capacity. The synthesized catalyst is efficient to degrade methyl orange in a wide range of pH. The kinetics of the catalysis reaction obeys the first order kinetics. The maximum degradation efficiency achieved was 97.9% and 84.3% in the presence and absence of light, respectively. The catalyst was easily recovered by decantation and its catalytic efficacy was more than 94% after 5 cycles. Hence, it is a promising alternative for decolourizing anionic dyes from wastewater.

Efficient adsorption of trace formaldehyde by polyaniline/TiO2 composite at room temperature and mechanism investigation

Formaldehyde is a common indoor environmental pollutant, which poses a great harm to human body. In this study, the adsorption behavior of a novel polyaniline/TiO2 (PANI/TiO2) for formaldehyde from air at room temperature, comparing to that of activated carbon and glass beads, was investigated, and the mechanism was interpreted in details. Polyaniline/TiO2 exhibited enhanced adsorption capacity of 0.67 mg g−1 for formaldehyde acquired from the Langmuir equation, which was higher than that of commercially used activated carbon of 0.50 mg g−1. While polyaniline/TiO2 could also be stably recycled by using simple acid-base treatment. Moreover, the initial adsorption rate order of polyaniline/TiO2>activated carbon > glass beads was acquired from kinetic study, confirming the superiority in the formaldehyde removal of our polyaniline/TiO2. Confirmed by adsorption isotherm study and various characterization experiments including X-ray photoelectron spectroscopy(XPS), Fourier transform infrared spectroscopy(FT-IR), Scanning electron microscope(SEM) and N2 adsorption-desorption isotherm, the adsorption of formaldehyde on to polyaniline/TiO2 may be through a chemical adsorption, in which the amine and imine groups in the polyaniline chain play important roles in the interaction between polyaniline/TiO2 composite and formaldehyde, and the formaldehyde may form as doping groups doped onto the polyaniline/TiO2. This contributes to the advanced adsorption affinity and capacity of polyaniline towards the formaldehyde even in a trace initial concentration, outperforming the commercially available activated carbon and glass beads very much. These novel properties allow polyaniline/TiO2 to be applied as an advanced formaldehyde scavenger in next generation to protect human being from the danger of formaldehyde, challenging present commercially available formaldehyde adsorbents greatly.

Hybrid TiO2-Polyaniline Photocatalysts and their Application in Building Gypsum Plasters.

Hybrid materials of conjugated polymer and titanium(IV) oxide have attracted considerable attention concerning their potential benefits, including (i) efficient exploitation of visible light, (ii) a high adsorption capacity for organic contaminants, (iii) and effective charge carriers separation. The new class of the photocatalysts is promising for the removal of environmental pollutants in both aqueous and gaseous phases. For the first time, in this study, the polyaniline (PANI)–TiO2 hybrid composite was used for the degradation of phenol in water and toluene in the gas phase. Polyaniline–TiO2 was prepared by the in situ polymerization of aniline on the TiO2 surface. The obtained hybrid material was characterized by diffuse reflectance spectroscopy (DR/UV-Vis), X-ray diffraction (XRD), fast-Fourier transformation spectroscopy (FTIR), photoluminescence (PL) spectroscopy, microscopy analysis (SEM/TEM), and thermogravimetric analysis (TGA). An insight into the mechanism was shown based on the photodegradation analysis of charge carrier scavengers. Polyaniline is an efficient TiO2 photosensitizer for photodegradation in visible light (λ > 420 nm). The trapping experiments revealed that mainly h+ and ˙OH were the reactive oxygen species that were responsible for phenol degradation. Furthermore, the PANI–TiO2 hybrid nanocomposite was used in gypsum plaster to study the self-cleaning properties of the obtained building material. The effect of PANI–TiO2 content on the hydrophilic/hydrophobic properties and crystallographic structure of gypsum was studied. The obtained PANI–TiO2-modified gypsum plaster had improved photocatalytic activity in the reaction of toluene degradation under Vis light.

A study of ac conductivity of nano TiO2–polyaniline based film

The nano composite film was prepared with 50 nm nano TiO2–polyaniline (PANI) and polyvinyl alcohol (PVA). The conducting polymer PANI/50 nm (TiO2) composite was synthesized by employing in situ polymerization techniques. This nanocomposite material was used with polyvinyl alcohol for forming the nano composite film in different compositions. The composite films were characterized for morphology and DC conductivity. SEM images also indicated the fibrous structure of the composite film. Dielectric behavior and ac conductivity of the composite films were investigated in the frequency range 20 kHz to 1 MHz. The nanocomposite film had shown high dielectric constant. It was observed that both dielectric properties decreased with increase in frequency.

Removal of methylene blue by Polyaniline/TiO2 hydrate: Adsorption kinetic, isotherm and mechanism studies

Polyaniline/TiO2 (PANI/TiO2), as a promising adsorbent, was synthesized and applied in the adsorption of methylene blue (MB) to evaluate the adsorption performance of PANI/TiO2 for cationic dye. The effects of dosage, pH, temperature and ionic strength on the adsorption efficiency were investigated in details. The adsorption isotherm and kinetic studies were conducted and the results revealed that the adsorption of MB on PANI/TiO2 was mainly controlled by chemical adsorption, membrane diffusion and intraparticle diffusion. The maximum adsorption capacity was 458.10 mg/g. HCl solution (0.1 mol/L) was used as stripping agent to study the regeneration stability of PANI/TiO2, and the adsorption efficiency can be maintained over 99% after 10 cycles. The N2 adsorption-desorption and Fourier Transform Infrared Spectroscopy of PANI/TiO2 before and after adsorption were compared and analyzed to obtain the information of adsorption mechanisms. The adsorption of MB by TiO2 mainly occurred on the surface hydroxyl and carboxyl groups, and was mainly heterogeneous multilayer physisorption. However, the adsorption of MB on PANI part occurred mainly on amino groups by hydrogen bonding and electrostatic interaction, and on benzene ring by π-π stacking and hydrophobic interaction, and was assigned to heterogeneous multilayer chemical adsorption by comparing the theoretical monolayer adsorption capacity and the actual adsorption capacity. After composition, PANI and TiO2 cooperated in the adsorption process of MB and exhibited their respective advantages. The PANI/TiO2 was an excellent adsorbent for organic cation dyes and was expected to be a kind of universal adsorbent for multiple pollutants.

Enhanced photocatalytic decolorization of methyl orange dye and its mineralization pathway by immobilized TiO2/polyaniline

An immobilized TiO2/polyaniline (TiO2/PANI) bilayer photocatalyst was fabricated to decolorize methyl orange (MO) dye in aqueous solution. The synergistic decolorization of MO occurred via photocatalysis by TiO2 top layer and adsorption by PANI sub-layer. The fabrication of the photocatalyst was pertaining to the loading of TiO2 (0.32–2.24 mg cm−2) and PANI (0.32–1.92 mg cm−2). Increasing the loading would increase the thickness of the layer whereas an increment in the adsorption rate constant would essentially increase the synergistic photocatalytic–adsorption in the decolorization of MO. The TiO2 and PANI layer loading was optimized at 1.27 and 0.63 mg cm−2, respectively. The optimized TiO2/PANI photocatalyst removed MO dye by four and three times more effectively than the TiO2 and PANI single layer, respectively. The aeration, which supplied the dissolved oxygen, was optimized at 40 mL min−1 of flow rate. The photocatalytic degradation mechanism of MO was initiated by the demethylation followed by the aromatic ring opening and ended with a complete oxidation of the aliphatic chain to become CO2 and H2O. The TOC and IC analyses confirmed the mineralization of MO.

Stability and Synergistic Effect of Polyaniline/TiO₂ Photocatalysts in Degradation of Azo Dye in Wastewater.

The polyaniline/TiO2 (PANI/TiO2) composite photocatalysts were prepared by the in situ chemical oxidation of aniline (An) in the presence of TiO2 particles. For this purpose, photocatalysts with different amounts of PANI polymer were prepared and analysed. Fourier-transform infrared (FT-IR) spectroscopy and thermogravimetric (TG) analysis indicated successful synthesis of the PANI polymer and its conductivity was also determined. The micrographs of field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were used to explain the impact of the aniline amount on the aggregation process during the synthesis of the composites. The smallest size of aggregates was obtained for the photocatalysts with 15% of PANI (15PANI/TiO2) due to the formation of homogenous PANI. The photocatalytic activity of studied PANI/TiO2 photocatalysts was validated by monitoring the discoloration and mineralization of Reactive Red azo dye (RR45) in wastewater. The 15PANI/TiO2 sample presented the highest photocatalytic efficiency under ultraviolet A (UVA) irradiation, in comparison to pure TiO2. This was explained by the formation of uniformly dispersed PANI on the TiO2 particles, which was responsible for the synergistic PANI-TiO2 effect.

Superior photocatalytic properties of carbonized PANI/TiO2 nanocomposites

A simple bottom–up method for the preparation of novel and very efficient photocatalytic nanocomposite system based on carbonized form of polyaniline (PANI) and colloidal TiO2 nanocrystals has been developed. The carbonized PANI/TiO2 nanocomposites were synthesized in a two-step procedure. Firstly, non-carbonized PANI/TiO2 nanocomposites were synthesized by the chemical oxidative polymerization of aniline (ANI) with ammonium peroxydisulfate, in the presence of colloidal TiO2 nanoparticles (TiO2 NPs) (d∼4.5nm). Initial [TiO2]/[ANI] mole ratios were 20, 50, and 80. In the second step, following the polymerization process, the carbonization of PANI/TiO2 nanocomposites was performed by thermal treatment in an inert atmosphere at 650°C. The morphological and structural properties of the carbonized nanocomposites were studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Raman spectroscopy. The accomplishment of complete carbonization of PANI in PANI/TiO2 nanocomposites was confirmed by Raman spectroscopy. The appearance of anatase and rutile crystal forms in TiO2 NPs upon carbonization, with mass ratio depending on the initial molar ratio of ANI and TiO2 NPs was revealed by XRD measurements, TEM, SEM and Raman spectroscopy. The photocatalytic activities of carbonized PANI/TiO2 nanocomposites were evaluated following the photocatalytic degradation processes of Rhodamine B and Methylene blue. Carbonized PANI/TiO2 nanocomposites showed higher photocatalytic efficacy compared to bare TiO2 NPs and non-carbonized PANI/TiO2 nanocomposites. The porosity and surface structure of carbonized PANI/TiO2 nanocomposites, as well as crystalline structure of TiO2, affect photocatalytic activity of nanocomposites.

TiO2–PANI/Cork composite: A new floating photocatalyst for the treatment of organic pollutants under sunlight irradiation

A novel photocatalyst based on TiO2–PANI composite supported on small pieces of cork has been reported. It was prepared by simple impregnation method of the polyaniline (PANI)–modified TiO2 on cork. The TiO2–PANI/Cork catalyst shows the unique feature of floating on the water surface. The as-synthesized catalyst was characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), UV–vis diffuse reflectance spectra (UV–vis DRS) and the Brunauer–Emmett–Teller (BET) surface area analysis. Characterization suggested the formation of anatase highly dispersed on the cork surface. The prepared floating photocatalyst showed high efficiency for the degradation of methyl orange dye and other organic pollutants under solar irradiation and constrained conditions, i.e., no-stirring and no-oxygenation. The TiO2–PANI/Cork floating photocatalyst can be reused for at least four consecutive times without significant decrease of the degradation efficiency.

Adsorption mechanism of phosphate by polyaniline/TiO2 composite from wastewater

The adsorption behavior of polyaniline/TiO2 (PANI/TiO2) for phosphate from wastewater was investigated, and the mechanism was interpreted in details in this study. PANI/TiO2 exhibited enhanced adsorption efficiency and high stability for phosphate removal in wide pH range (1–6) compared with PANI and TiO2. The equilibrium time was much shorter than other similar sorbents reported, like HFO-201 and La-201, and 60min was enough for the adsorption of 98% phosphate (10mg P/L). After 5 times reuse of the NaOH (0.5molL−1) for desorption, phosphate solution was concentrated from 10mg P/L to 180mg P/L without obvious loss of adsorption and desorption efficiency. The mechanism of the phosphate adsorption onto PANI/TiO2 was revealed with the aid of SEM, XRD, EDS, FTIR and XPS. Two adsorption sites of protonated imino groups in PANI chains and the Ti(OH)n(4-n)+ from TiO2 part were verified, and the binding force of Ti-P was the main pathway for the removal of phosphate. Generally, electrostatic interaction, ion-exchange and hydrogen bond were demonstrated to be involved during the adsorption. The synergistic effect of the PANI and TiO2 make the organic/inorganic composite a promising sorbent for phosphate removal from wastewater.

Preparation and performance of polyaniline–multiwall carbon nanotubes–titanium dioxide ternary composite electrode material for supercapacitors

Multi-walled carbon nanotubes (MWNTs), and titanium oxide (TiO2) were incorporated in polyaniline (PANI) to enhance the pseudocapacitance and cycle stability of PANI. PANI–MWNTs–TiO2, ternary composite was prepared by in-situ chemical polymerization of aniline in the presence of MWNTs and TiO2. Morphology analysis of ternary composite revealed the uniform covering of MWNTs by PANI nanofibers and TiO2 nanoparticles. The specific capacitance of PANI–MWNTs–TiO2 is 270 F g−1, much higher than that of MWNTs (30 F g−1) and PANI (210 F g−1) electrodes. PANI–MWNTs–TiO2 showed good rate capability with excellent cycling stability.

A molecular view on a polyaniline–TiO2 nanostructured thin film: Effect of temperature and pressure on the thermal, mechanical, and dynamical properties

The present work adopts experimental studies and molecular dynamics (MD) simulations to investigate the thermal, mechanical, and dynamical properties of polyaniline (PANI) coated on a TiO2 nanostructured film. At first, a series of the PANI and TiO2 nanostructured thin films were prepared using the sol–gel dip-coating method. The dynamic mechanical thermal analysis (DMTA) was used to measure glass transition temperature, Tg. AFM-based nano-indentation tests were used to determine the values of hardness, Young's modulus and Poisson's ratio of the prepared thin films. Second, MD simulations were performed using COMPASS force field associated with energy minimization approach. The density and free energy profiles were calculated to determine the molecular structure and thermodynamic equilibrium state of the simulated PANI structures with different monomer chains at various temperatures. The value of Tg of the PANI film under different pressures was also determined from the simulation. The mechanical properties of PANI film and the PANI–TiO2 interface such as the normal stresses, tangential stresses, surface tension, bulk and shear modulus and Poisson's ratio were determined computationally. The dynamic properties of simulated films were studied by the terms of torsion time autocorrelation function. In all cases, MD simulation results were in good to excellent agreement with the experimental data.

Electrocatalytic properties of polyaniline–TiO2 nanocomposites

An efficient methodology of polyaniline–TiO2 nancomposite (PAniTNC) was developed through various proportions of ceramic added by chemical polymerization at room temperature. The chemical polymerization reactions were carried out using potassium perdisulphate as an oxidizing agent. The particle size of PAniTNC was found in the range of 8–15 nm as analysed by transmission electron microscopy. The Ti–O characteristic stretching bands at 630 and 558 cm−1, indicating the presence of TiO2 in polyaniline matrix was confirmed by fourier transform infrared spectroscopy. The characterization of the nanocomposite crystalline shape was carried out using X-ray diffraction method. Thermogravimetric and differential scanning calorimetry analyses indicate high thermal stability. SEM analysis showed mixed granular nature of the polymer–ceramic nanocomposites. EDX analysis shows the presence of Ti, C and N in composites. Cyclic voltammetric studies exhibit good adherent behaviour on the electrode surface at pH 1.0. It reveals the presence of oxidation peak at 0.417 V and reduction peak at 0.285 V. It has been observed that PAniTNC-modified GCE has good oxygen reduction ability, and also enhances methanol reduction.

Influence of TiO2 nanoparticles on formation mechanism of PANI/TiO2 nanocomposite coating on PET fabric and its structural and electrical properties

Polyester fibers gained significant share from all other man-made fibers, but despite numerous advantages a characteristic static electricity generation is still seeking innovative solutions. In order to improve electrical properties of poly(ethyleneterephthalate) (PET) fabric, coating consisting of polyaniline/TiO2 (PANI/TiO2) nanocomposite was deposited on its surface. Coating was synthesized in acidic medium by the chemical oxidative polymerization of aniline with ammonium peroxydisulfate (APS) in the presence of colloidal TiO2 nanoparticles (d~4.5nm) and PET fabric. The morphology, molecular structure and dielectric properties of PANI/TiO2 nanocomposites were studied by scanning electron microscopy (SEM), Raman and dielectric spectroscopies. SEM analysis revealed the formation of non-uniform PANI coating on the reference PET sample. In contrast, uniform PANI/TiO2 coating on the surface of PET fabric was generated when TiO2 nanoparticles were engaged. The existence of conductive emeraldine salt form of PANI and phenazine units was confirmed by Raman spectroscopy. Formation mechanisms of PANI and PANI/TiO2 coatings on PET fabrics were proposed. The presence of TiO2 nanoparticles significantly affected the dielectric properties (permittivity and loss tangent) and AC conductivity of PANI/TiO2 coated PET fabrics. PET fabrics coated by PANI/TiO2 nanocomposite showed up to two orders of magnitude higher conductivity in the measured frequency region compared to PANI coated PET fabric.

Preparation of polyaniline–TiO2 nanotube composite for the development of electrochemical biosensors

The significant and novel aspect of this work lies in the preparation of a polyaniline (PANI)–TiO2 nanotube (TNT) composite which can provide excellent biocompatibility, good electrical conductivity, low electrochemical interferences and high signal-to-noise ratio for the development of electrochemical biosensors. Using a hydrothermal method, TiO2 nanoparticles were initially transformed into TNTs, on which aniline was then polymerized by oxidative polymerization to form an intimate and uniform PANI–TNT composite. After being characterized by different spectroscopic techniques, the PANI–TNT composite was used to immobilize glucose oxidase (GOD) for the construction of an electrochemical biosensor. The direct electrochemistry and electro-catalytic performance of the biosensors based on PANI–TNTs and TNTs was studied by cyclic voltammetry. The direct electrochemistry of GOD on PANI–TNTs modified electrodes was achieved and the heterogeneous electron transfer rate constant (ks) for GOD was estimated to be 9.3s−1. Furthermore, the redox currents of GOD at PANI–TNT modified biosensor were improved by ∼55% compared to that at TNT modified biosensor. The PANI–TNT modified GOD biosensor exhibited good sensitivity (11.4μAmM−1), wide dynamic range (10–2500μM) and low limit of detection (0.5μM), which are attributed to the improved properties of the composite.

Charge transfer in photorechargeable composite films of TiO2 and polyaniline

A photorechargeable battery (PRB) is a photovoltaic device having an energy storage function in a single cell. The photoactive electrode of PRB is a bilayer film consisting of bare porous TiO2 and a TiO2–polyaniline (PANi) mixture that work as a photovoltaic current generator and an electrochemical energy storage by ion dedoping, respectively. To study the charge transfer between TiO2 and PANi, the photorechargeable quantum efficiency QE ([electron count on discharge]/[incident photon count on photocharge]) was measured by varying the thickness LS of the TiO2–PANi mixture. The quantum efficiency QEuv for UV photons had a maximum of ∼7% at LS ∼ 7 µm. The time constant τTP for the charge transfer was about 10−1 s, which was longer ten times or more than the lifetime of excited electrons within TiO2. These facts reveal that the main rate-limiting factor in the photocharging process is the charge transfer between TiO2 and PANi.

Fabrication of polyaniline nanowire/TiO2 nanotube array electrode for supercapacitors

A per literature study, work of PANI (polyaniline) nanowire/TiO2 nanotube arrays with highly porous structures and good capacitive characteristics are not prepared by electrochemical methods. The authors have described the TiO2 nanotube arrays which are fabricated by simple anodization of Ti sheet in ammonium fluoride/glycerol solution. PANI nanowires were deposited on the TiO2 nanotube layer by electro-polymerization. TiO2 nanotube layer to promote the formation of a concentration gradient of aniline monomer, and thus indirectly played a role in the dynamic template. Structural and morphological characterizations indicate that the PANI nanowires and TiO2 nanotubes have diameters of 200–300 nm and 60–100 nm, respectively. The intricate cooperation of the two materials enables the supercapacitor to work in a widened 1.2-V potential window. The specific capacitance of these electrodes is around 897.35 F g−1 at a current density of 0.21 A g−1 in 0.05 M H2SO4. The modified electrodes also show high cycling stability and maintain 86.2% of the initial capacity after 1500 cycles. The coexistence of mesopores, nanowires, and nanotubes favors the fast penetration of the electrolyte, facilitates ion diffusion, and shortens the charge transfer distance, all of which lead to the superior electrochemical performance of PANI nanowire/TiO2 nanotube arrays.