Electrochromic and electrochemical capacitive properties of tungsten oxide and its polyaniline nanocomposite films obtained by chemical bath deposition method

Polyanine and its nanocomposite WO3/PANI films were deposited on fluorine doped tin oxide (FTO) glassslides by simple chemical bath deposition method. The morphology structure of the composite film wasstudied using atomic force microscopy (AFM) and scanning electron microscopy (SEM), while the elec-trochemical capacitive properties were determined using cyclic voltammetry (CV), chronopotentiometry(CP) and electrochemical impedance spectroscopy (EIS). The WO3/PANI nano-composite exhibited mul-tiple colors (electrochromism) during the CV scans, from brownish green to transparent to light greenthen back to brownish green. Surprisingly, the integration of the PANI with the WO3led to synergisticperformance of nanohybrid wherein a true electrochemical double layer capacitor was obtained. Also,interestingly and unlike literature reports, the CBD method led to excellent capacitance retention (>98%)of the PANI even at 1000 continuous cycles. This work demonstrates that simple CBD can be used toget WO3/PANI films that give good electrochromism and pseudo-capacitance comparable to the onesobtained by other methods. Hence the obtained nanocomposite film of WO3/PANI can be a promisingmaterial for electrochromic and energy storage applications.US Army Research Laboratory–Broad Agency Announcement (BAA) (under Contract number W911NF-12-1-0588).http://www.elsevier.com/locate/electactahb201

Study of the extrinsic properties of ZnO:Al grown by SILAR technique

Hliníkem dopované tenké vrstvy ZnO s křemeni-podobnou strukturou byly úspěšně deponovány na skelné substráty postupnou iontově adsorpční reaktivní metodou. Byl zkoumán vliv procentního složení hliníkových dopantů na nanostrukturu „květinám-podobných“ klastrů ZnO, morfologii a jejich optické vlastnosti. Tenké vrstvy ZnO, které krystalizují v hexagonální wurtzitové struktuře o velikosti krystalitů 44, 51, 56 a 43 nm pro intrinsickou vrstvu a vrstvy s 1, 3 a 5-ti procentním dotováním hliníkem. Přednostní orientace krystalitů je ve všech případech ve směru [001] kolmém na podložku. Ramanova spektroskopie odhalila pokles intenzity charakteristické spektrální čáry ZnO v důsledku substituce iontů Zn2+ atomy Al3+ a předpokládané potenciálové fluktuace slitinové neuspořádanosti. Zavedením Al3+ dopantů se významně zvýšila optická šířka zakázaného pásma ZnO.Aluminum-doped ZnO thin films with pebble-like structures have been successfully deposited on glass substrates by successive ionic layer adsorption reaction method. The effect of percentage composition of the aluminum dopants on the flower-like clusters of the ZnO nanostructures on the structure, morphology, and optical properties was investigated. The ZnO thin films which were crystallized in hexagonal wurtzite structures with crystallite sizes of 44, 51, 56, and 43 nm for the intrinsic and 1, 3, and 5% Al-doped ZnO thin films, respectively. Preferred orientation of crystallites is in all cases in [001] direction perpendicular to the sample surface. The Raman spectroscopy revealed decrease in the intensity of the ZnO characteristic peak due to the substitution of the Zn2+ atoms by the Al3+ and attributed to potential fluctuations of the alloy disorder. The introduction of the Al3+ dopants significantly increased the optical band gap

Electronic thermal conductivity, thermoelectric properties and supercapacitive behaviour of conjugated polymer nanocomposite (polyaniline-WO

A facile two-step, binder-free, chemical bath deposition (CBD) method was successfully employed in the synthesis of WO3 nanograins onto the matrix of conjugated polymer (polyaniline). The X-ray diffraction (XRD) results showed that the nanocomposite retained monoclinic phase of WO3 even when dispersed in polyaniline matrix. Owing to the synergistic effect offered by both the nanocomposite and structured metal oxide which may enhance the surface area, polyaniline-WO3 nanocomposite exhibited good specific capacitance. Polyaniline-WO3 yielded maximum specific capacitance ~96 F/g at scan rate of 5 mV/s in 0.5 M H2SO4 electrolyte. With the electronic thermal conductivity showing strong dependence on temperature, the estimated dimensionless figure of merit zT ~ 10−3 shows that the polymer nanocomposite (PNC) is promising as a new type of thermoelectric material. The electrochemical impedance spectroscopy showed that the PNC exhibited both pseudocapacitive and electric double layer capacitance behaviour

Activation parameters of conjugated polyaniline electrolyte via dielectric relaxation technique

830-836The synthesis and relaxation mechanism of polyaniline electrolyte in form of thin film by oxidative polymerization in the presence of inorganic acid have been reported. The films have been characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, 2-point probe and UV-Vis absorption spectroscopy. The mechanism of electrical conductivity for the disordered system has been explained in terms of Mott’s variable-range hopping for the intrinsic conduction of the protonated long chain. The dielectric parameters including real part, imaginary part and loss tangent have been measured between the wavelength range 400 – 1100 nm. These have been employed in the determination of dielectric relaxation time τ which exhibits Arrhenius-like behaviour. Finally, the temperature dependent relaxation time which is a function of activation energy of dipole orientation otherwise known as Gibbs free energy ∆G#, has been utilized in estimation of some thermodynamic parameters such as enthalpy ∆H# and entropy ∆S#. The SEM shows an aggregation of randomly oriented fibrous network of polyaniline on the surface of substrate. Fourier transform infrared confirms the acoustic vibrational modes of the long chain polymer

Electrochromic and electrochemical capacitive properties of tungsten oxide and its polyaniline nanocomposite films obtained by chemical bath deposition method

Polyanine and its nanocomposite WO3/PANI films were deposited on fluorine doped tin oxide (FTO) glassslides by simple chemical bath deposition method. The morphology structure of the composite film wasstudied using atomic force microscopy (AFM) and scanning electron microscopy (SEM), while the elec-trochemical capacitive properties were determined using cyclic voltammetry (CV), chronopotentiometry(CP) and electrochemical impedance spectroscopy (EIS). The WO3/PANI nano-composite exhibited mul-tiple colors (electrochromism) during the CV scans, from brownish green to transparent to light greenthen back to brownish green. Surprisingly, the integration of the PANI with the WO3led to synergisticperformance of nanohybrid wherein a true electrochemical double layer capacitor was obtained. Also,interestingly and unlike literature reports, the CBD method led to excellent capacitance retention (>98%)of the PANI even at 1000 continuous cycles. This work demonstrates that simple CBD can be used toget WO3/PANI films that give good electrochromism and pseudo-capacitance comparable to the onesobtained by other methods. Hence the obtained nanocomposite film of WO3/PANI can be a promisingmaterial for electrochromic and energy storage applications.US Army Research Laboratory–Broad Agency Announcement (BAA) (under Contract number W911NF-12-1-0588).http://www.elsevier.com/locate/electactahb201