Polyaniline TiO2 Research Articles

Fabrication, characterization and application of a reusable immobilized TiO2–PANI photocatalyst plate for the removal of reactive red 4 dye

A method for immobilizing TiO2–PANI composite using ENR and PVC as adhesives was successfully developed. The immobilized system known as TiO2/PANI/ENR/PVC plate was characterized by FTIR, Raman, diffuse reflectance UV–vis, photo luminescence spectroscopy and HRTEM. The optimum weight ratio for the TiO2:PANI composite was 1:0.0035. The band gap energy of the optimum immobilized composite TiO2/PANI/ENR/PVC (1:0035) was 2.86eV where polyaniline (PANI) formed a core–shell coating of about 0.9nm with a strong TiO2–PANI interaction. Photo-etching of the immobilized TiO2/PANI/ENR/PVC (1:0.0035) composite for 7h increased its surface area and improved its photocatalytic activity. TiO2/PANI/ENR/PVC (1:0.0035)-7h was visible light sensitive where 85% of 30mgL−1 reactive red 4 (RR4) dye was decolorized after 60min of irradiation. The immobilized TiO2/PANI/ENR/PVC (1:0.0035)-7h was reusable and its photocatalytic activity was sustainable with an average pseudo first order rate constant value of 0.103±0.002min−1. Adding PANI to the immobilized P25 TiO2 has enhanced its photocatalytic activity throughout the entire ten recycled applications due to the increased BET surface area and lower ecb and h+ recombination.

An energy efficient photocatalytic reduction of 4-nitrophenol

An energy efficient (EEO value 80kWh/m3) method for photocatalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by using TiO2-Polyaniline (TiO2-PANI) composite in presence of visible light is presented in this article. Reduction of 4-NP in presence of a well known reducing agent NaBH4 is inert in aqueous suspensions. Here we observed the high adsorptive and electron conducting capacity of TiO2-PANI favors the reduction of 4-NP to 4-AP. Steady drop off in the absorbance at 400nm monitored over UV–vis spectrophotometer confirms the decrease in the concentration of 4-NP. Prepared catalyst found to be highly efficient in the reduction of 4-NP under visible light irradiation.

Optimized synthesis of polyaniline-TiO2 composites for corrosion protection of carbon steel using design of experiment (DOE)

The present work investigates the synthesis and optimization of polyaniline-TiO2 (PANI-TiO2) composite using design of experiment (DOE) based on Plackett-Burman technique. This composite is capable of corrosion protection of steel due to different oxidation states of polyaniline and TiO2 semi conductive properties. The main monitored parameters were temperature, stirring time, weight and volume of reagents during the optimization process. The synthesized PANI-TiO2 composite used in preparation of coating formulations based on epoxy resin system was characterized by FT-IR, XRD and SEM techniques. Protective performance of the coatings was tested using some ASTM methods. It was concluded that the optimized composite provides an effective coating which can easily resist for 800 h in salt spray test condition.

Visible-light photocatalytic degradation performances and thermal stability due to the synergetic effect of TiO2 with conductive copolymers of polyaniline and polypyrrole

Conductive polypyrrole-polyaniline/TiO2 nanocomposites (PPy-PANI/TiO2) were prepared by in situ oxidative copolymerization of pyrrole and aniline monomers in the presence of TiO2. For comparison studies, polypyrrole/TiO2 (PPy/TiO2) and polyaniline/TiO2 (PANI/TiO2) were also prepared. The samples were characterized by X-ray diffraction, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, zeta potential analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis and photocurrent tests. In contrast to PPy/TiO2 and PANI/TiO2, PPy-PANI/TiO2 exhibits obvious absorption in the visible-light range, and is much superior to PPy/TiO2 and PANI/TiO2 in thermal stability. It is found that PPy-PANI/TiO2 performs well in the visible-light photocatalytic degradation of 4-nitrophenol. The optimized pyrrole : aniline : TiO2 molar ratio for best performance is 0.75 : 0.25 : 100. The efficacy of PPy-PANI/TiO2 is attributed to its conductivity, conjugated structure, as well as to the synergy amidst polypyrrole, polyaniline and TiO2.

Synthesis of TiO2–polyaniline core–shell nanofibers and their unique UV photoresponse based on different photoconductive mechanisms in oxygen and non-oxygen environments

The TiO2-polyaniline (PANI) core-shell nanofibers with unique ultraviolet (UV) photoresponse were designed and fabricated. When the core-shell nanofibers were tested in an oxygen (O2) and a non-oxygen environment under UV illumination, respectively, a decrease and an increase in photoconduction were observed, which suggested different photoconductive mechanisms of the core-shell materials in different environments.

Simplified synthesis of polyaniline–TiO2 composite nanotubes for removal of azo dyes in aqueous solution

In this work, polyaniline (PANI) nanotubes (150–200 nm diameter) containing titanium dioxide (TiO2) nanoparticles (about 23 nm diameter) were synthesized through a self-assembly process by the simplified template-free method. It was found that both PANI–TiO2 and PANI nanotubes exhibited significant adsorptivity and photocatalytic activity towards azo dyes; with 1 h adsorption and subsequent 2 h photochemical treatment under Ultra-Violet (UV) illumination, total removal ratios of 98.1 and 98.6 % were achieved for methyl orange and orange II, respectively. The morphology of the product was characterized by scanning electron microscope (SEM). The specific surface area of PANI–TiO2 nanotubes was found to be 16.5 m2/g, compared with 0.27 m2/g for normal polyaniline. Infrared spectrum (IR) and X-ray diffraction (XRD) characterization were employed to analyze the chemical structure of the as-prepared materials. In addition, the one-dimensional material retained a relatively high removal ability after four repeated utilizations. This may provide a new approach for effective separation of organic contamination from aqueous solution by using organic–inorganic semiconductor composites with one-dimensional nanostructure.

Polyaniline–TiO2 hybrid‐coated cotton fabric for durable electrical conductivity

AbstractA polyaniline–TiO2 hybrid was coated on cotton fabric to make it electrically conductive. A One‐pot method of synthesis with acetic acid medium was used, in which TiCl4 was used as precursor. The oxidative polymerization of aniline adsorbed on TiO2 (anatase form) was performed in the presence of cotton fabric. Fabric crystallinity was least affected by the coatings, as confirmed by XRD analysis. FTIR studies revealed interactions between fiber and hybrid. The morphological study through SEM showed the uniform coating of hybrid over the fibers of the cotton fabric and AFM analysis revealed the rod‐like structure of the hybrid. The strength of the coated fabrics was assessed using abrasion tests. The electrical conductivity was determined using electrochemical impedance spectroscopy (EIS).The conductivity value varied with respect toTiO2 content and ranged in the order 10−4 to 102S/cm. The effect of atmospheric aging was assessed. A more durable conductivity was observed in hybrid‐coated fabric than pristine polyaniline‐coated fabric. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Development of nanostructured polyaniline–titanium dioxide gas sensors for ammonia recognition

AbstractThe performance at room temperature of nanostructured polyaniline (PANi)–titanium dioxide (TiO2) ammonia gas sensors was investigated. The PANi–TiO2 thin‐film sensors were fabricated with a spin‐coating method on glass substrates. PANi–TiO2 (0–50%) sensor films were characterized for their structural, morphological, optical, and various gas‐sensing properties. The structural analysis showed the formation of nanocrystalline TiO2, whereas PANi exhibited an amorphous nature. Morphological analysis of the PANi–TiO2 nanocomposites film revealed a uniform distribution of TiO2 nanoparticles in the PANi matrix. The absorption peaks in the Fourier transform infrared spectra and ultraviolet–visible spectra of the PANi–TiO2 composite film were found to shift to higher wave numbers compared to those observed in pure PANi. The observed shifts were attributed to the interaction between the TiO2 particles and the PANi molecular chains. The gas‐sensing properties showed that the sensors exhibited selectivity to ammonia (NH3) at room temperature. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

TiO2/WO3 hybrid structures produced through a sacrificial polymer layer technique for pollutant photo- and photoelectrooxidation under ultraviolet and visible light illumination

TiO2/WO3 hybrid structures were produced on graphite substrates following a three step procedure: (i) electrochemical deposition of WO3 under potentiostatic conditions, (ii) electrochemical deposition of TiO2–polyaniline (PANI) composite layers by potentiostatic polymerization of aniline in the presence of TiO2 nanoparticles, (iii) high temperature (450 °C) treatment for decomposition of the PANI structure. Experiments on the photoelectrochemical response of the composite layers were carried out by cyclic voltammetry and chronoamperommetry in the dark and under illumination by using low power lamps emitting in the visible and UV spectrum ranges. The oxidation of three pollutants—oxalate ions, methanol and malachite green was used to evaluate the photoelectrocatalytic activity of the TiO2/WO3 structures. The photocurrents registered for the photooxidation of oxalate were higher than photocurrents measured at hybrid TiO2/WO3 electrodes obtained in conventional two-step electrodeposition of WO3 and subsequently TiO2 from corresponding salt solutions. The efficiency of the malachite green photodegradation in our experiments was also about two orders of magnitude higher than that obtained in TiO2/WO3 structures synthesized in a conventional way. These results are (very probably) due to the proposed synthetic approach involving PANI polymer layer as an immobilizing matrix and the opportunity to disperse homogeneously TiO2 nanoparticles on the WO3 surface provided.

Synthesis and photocatalytic activity of polyaniline–TiO2 composites with bionic nanopapilla structure

Polyaniline (PANI)–TiO2 nanocomposites possessing both nano and microscale structures were prepared through a facile hydrothermal route in the presence of PANI. The nanopapilla particles were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, X-ray photoelectron spectra, X-ray diffraction, FTIR spectra, UV–Vis spectroscopy, and N2 adsorption analysis, etc. The results show that the composites possess both nano and microscale structures. The TiO2 nanorods are dispersed on PANI with one end fixed to the surface. The photocatalytic properties of the powders were verified by the photodegradation of gaseous acetone under UV (λ = 254 nm) and visible-light irradiation (λ > 400 nm). In fact, the photocatalytic effects exhibited by the composite particles were superior to that of pure TiO2 and P25 samples. This excellent behavior is attributed to the structural features of PANI–TiO2 microspheres and the synergistic effect between PANI and TiO2 which facilitates a larger amount of surface active sites. This in turn causes a faster charge separation and slower charge recombination which results in a more efficient decomposition of gaseous pollutants.

Synthesis and characterization of polyaniline nanofiber/TiO2 nanoparticles hybrids

The hybridization of polyaniline (PANI) and TiO2 leads to unique materials, which exhibit the enhancement of photocatalytic properties. Further improvement requires high dispersion state of TiO2 in the hybrid. In this study, highly dispersed PANI nanofiber/TiO2 nanoparticles hybrids were obtained by modifying the surface charge of TiO2 nanoparticles via layer by layer (LbL) technique. The structural studies of the hybrids confirmed the presence of PANI along with anatase TiO2 nanoparticles. The degradation of methylene blue (MB) in an aqueous solution under visible light irradiation was carried out to study the photocatalytic activity of the hybrids. The hybridization of PANI nanofiber and TiO2 nanoparticles resulted in an enhancement of photocatalytic activity for visible light.

One-pot synthesis of hybrid TiO2–polyaniline nanoparticles by self-catalyzed hydroamination and oxidative polymerization from TiO2–methacrylic acid nanoparticles

A simple self-catalyzed hydroamination method for creating hybrid TiO(2)-polyaniline core-shell nanoparticles (NP) has been shown. Hybrid NPs with a range of possible sizes are afforded in high yield under mild reaction conditions and simultaneously show improved charge transport and electrochromic behavior compared to either polyaniline alone or physically blended with TiO(2).

Nanocomposite Membranes of Poly(Vinyl Alcohol) Loaded with Polyaniline-Coated TiO2 and TiO2 Nanoparticles for the Pervaporation Dehydration of Aqueous Mixtures of 1,4-Dioxane and Tetrahydrofuran

Nanocomposite membranes of poly(vinyl alcohol)–polyaniline (PANI)-coated titanium dioxide (PVA–PANI–TiO2), as well as TiO2, cross-linked with glutaraldehyde were tested for their suitability in dehydrating aqueous mixtures of 1,4-dioxane or tetrahydrofuran (THF) by pervaporation (PV). The effect of feed composition and filler loading on PV separation performance was examined. Sorption studies were performed in feed mixtures to assess the extent of interaction between membranes and feed components. The addition of a small amount of nano-sized filler particles into a cross-linked PVA membrane was responsible for an increase in membrane selectivity to water. Among the cross-linked nanocomposite PVA membranes, TiO2 coated with 0.5 wt% PANI gave higher sorption than other membranes. Sorption of the cross-linked (unfilled) PVA membranes was higher compared to all the nanocomposite membranes. Addition of filler particles reduced the extent of sorption with improved membrane performance.

Uniform TiO2–PANI composite capsules and hollow spheres

Here we demonstrated a simple and reliable method to prepare single or multiple core/shell structured capsules and then demonstrate how to produce single or multiple-layer hollow spheres. Those capsules or hollow spheres could be made of organic and/or inorganic functional materials depending on the experimental design. Core–shell composite capsules consisting of TiO2–polyaniline (PANI) shell and polystyrene (PS) core were prepared by using core–shell structured sulfonated-PS spheres as templates. Aniline was polymerized in the shell of sulfonated-PS spheres. Since the PANI was in situ doped by sulfonic acid, the as-synthesized composite capsules had good conductivity. After PS cores were dissolved in solvent, hollow TiO2–PANI spheres formed, which could be further calcined to produce mesoporous hollow TiO2 spheres. The cavity size of the hollow spheres was uniform, at approximately 170nm in diameter and with a shell thickness of 30nm. The cavity size and the shell thickness can be synchronously controlled by adjusting the sulfonation reaction time of PS spheres. Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray powder scattering were employed to characterize these as-prepared spheres.

Photocatalytic degradation of Allura red and Quinoline yellow with Polyaniline/TiO2 nanocomposite

A series of polyaniline/TiO2 (PANI/TiO2) composites has been prepared from aniline and TiO2 under various polymerization conditions. Among these conditions are the concentrations of aniline, ammonium persulfate, HCl, sodium dodecyl sulfate, and the amount of TiO2. More composites were obtained by replacing HCl with H2SO4, H3PO4, and HNO3 as dopant acids. Scanning electron microscopy, UV/vis-diffuse reflectance spectroscopy, FTIR and TGA were used to characterize some of these composites. The rate of degradation of dyes with these composites followed first-order kinetics in the dye concentration. The activity of the composite towards the degradation process differs according to the experimental polymerization conditions. The activity increased with the increase in the concentration of aniline monomer and persulfate, but decreased with increasing the concentration of HCl, sodium dodecyl sulfate, and the amount of TiO2. The activity of composites formed in the presence of different acids followed the order H2SO4>H3PO4>HCl>HNO3. The rate of composite/dye interaction was enhanced with the UV-irradiation, increasing load of composite, and temperature. It was retarded with the increase in initial dye concentration and pH. The activation parameters were determined and a plausible mechanism was proposed.

Photovoltaic Properties of Polyaniline-Titania Composite for Hybrid Solar Cells Applications

AbstractSolar energy harvesting has been extensively studied in the last three decades to provide a green energy source. Hybrid photovoltaics (HPV) based on titania (TiO2) are researched for their easiness of production and low cost. Nanostructured mesoporous titania films and conductive polymers were used recently to form hybrid solar cells [1]. TiO2, mainly an n-type semiconductor with a band gap of 4.2 eV, is employed in several applications from which paints form the highest world use of titania making it an attractive material to use in HPV industry. On the other side, our targeted conductive polymer is polyaniline (PANI), a hole conductor polymer, which is used in such HPV cells due to its high charge-carriers mobility, absorption coefficient in the visible range and environmental stability. PANI and nanocrystalline TiO2 films fabricated using spin coating or layer by layer assembly techniques behave as a p-n heterojunction diode and can be used as solar cells [2-4].Precursor solutions are prepared by polymerizing aniline-HCl inside an aqueous solution of titania. To study the effect of the precursor concentration on the PANI-TiO2 composite, polymerization of aniline is held in diverse TiO2 concentrations in water. Industrial grade TiO2 powders with particle size ranging from 200 nm to several μm are used. PANI-TiO2 precursor solutions are dip coated or slot dyed on various substrates such as PMMA, PET and PP, all with metal oxide conductive coatings. Bulk PANI-TiO2 pellets are prepared for comparison. The electrical and photovoltaic properties of the obtained films and pellets are investigated to choose the optimum blend composition for HPV cell. Finally a theoretical study and an analytical model of the HPV cell are presented relating the size of TiO2 and PANI particles and their respective geometrical distribution inside the blend to the transport characteristics of charge carriers and the overall efficiency of the HPV cell.[1] M. McGehee, MRS Bulletin, Vol. 34, No. 2, February 2009.[2] Z. Liu, W. Guo, D. Fu and W. Chen, Synthetic Metals, Vol. 156, pp. 414–416, 2006.[3] Z. Liu, J. Zhou, H. Xue, L. Shen, H. Zang and W. Chen, Synthetic Metals, Vol. 156, pp. 721–723, 2006.[4] X. Zhang, G. Yan, H. Ding and Y. Shan, Materials Chemistry and Physics, Vol. 102, pp. 249–254, 2007.

Influence of TiO2 and SiO2 on Electrochemical, Optical and Electrical Conductivity of Polyaniline, Poly(o-toluidine) and Their Co-polymer

A conducting composite of polyaniline, poly(o-toluidine) and poly(aniline-co-o-toluidine) using incorporation of TiO2 and SiO2 was prepared by electrochemical polymerization. The films were electro-polymerized in solution containing 0.1 M monomer(s), 1 M sulphuric acid as supporting electrolyte and 10−5 M TiO2 and SiO2, applying a sequential linear potential scan rate of 50 mV/s between −0.2 and 1.0 V versus Ag/AgCl electrode. The characterization of the composites was done by cyclic voltammetry, UV-Vis spectroscopy, electrical conductivity and thermogravimetric analysis. It is observed that the UV-Vis peaks are appearing in the region of conducting emerladine salt (ES) phase. In overall study, the polymers prepared using TiO2 have higher conductivity than SiO2, with the highest conductivity observed for the polyaniline–TiO2 conducting composite. The composite does not lose its colour at higher temperature and, hence, can be utilized as conductive pigments required for anti-electrostatic applications.

Polyaniline–TiO2 nano-composite-based trimethylamine QCM sensor and its thermal behavior studies

Abstract Inorganic/organic composites are very attractive due to synergetic behavior and a wide range of potential use. A polyaniline–TiO2 nano-composite, obtained by combination of chemical polymerization and a sol–gel method, was deposited on the electrode of quartz crystal to implement a quartz crystal microbalance (QCM) chemical sensor. The morphology of the composite film was studied by scanning electron microscopy (SEM) measurements. The coated quartz crystal and a non-coated quartz crystal were mounted in a sealed chamber, and their frequency difference was monitored. When analyte vapor was injected into the chamber, gas absorption decreased the frequency of the coated quartz crystal and thereby caused an increase of the frequency difference between the two crystals. The frequency difference change response towards trimethylamine was evident and could be recovered by N2 purgation easily. The calibration curve towards trimethylamine, its long-term stability and selectivity were investigated. The thermal behavior of the sensing characteristics was compared with that of a polyaniline QCM sensor. Fourier transform infrared (FTIR) spectra of polyaniline and polyaniline–TiO2 nano-composite and QCM data under various conditions were used to study the effect of thermal treatment.

Synthesis and characterization of conductive polyaniline/TiO2 composite nanofibers

Fibrillar conductive polyaniline/TiO2 (PANI/TiO2) nanocomposites with different TiO2 amount were synthesized with a template-free in situ polymerization method and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and conductivity measurement. The morphology determination shows that the PANI/TiO2 composite nanofibers are relatively uniform with the diameter and length in the range of 20–40 nm and 390–420 nm respectively. It also shows that the TiO2 of the composite is rutile crystalline and PANI has some degree of crystallinity. The IR measurement indicates that there is a strong interaction between the PANI and TiO2 nanoparticles, and it has a beneficial effect on the thermal stability of the composite nanofiber. The conductivity of PANI/TiO2 composites changes with TiO2 amount and reaches an optimum value of 2.86 S/cm at 11.1 wt% TiO2.

Characterization and dielectric properties ofpolyaniline–TiO2 nanocomposites

Nanocomposites of polyaniline (PANI)–titanium dioxide(PANI–TiO2) are preparedfrom a colloidal sol of TiO2 nanoparticles. The dc and ac conductivities of samples with different concentrations ofPANI have been investigated as a function of frequency and temperature. The dcconductivity follows three-dimensional variable range hopping. The ac conductivityhas been interpreted as a power law of frequency. The temperature variationof the frequency exponent suggests a correlated barrier hopping conductionprocess in the nanocomposites. A very large dielectric constant of about 3700at room temperature has been observed. An electric modulus presentation isused to interpret the dielectric spectra. The interface between polyaniline andTiO2 plays an important role in yielding a large dielectric constant in the nanocomposite.