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

Radioactivity level and toxic elemental concentration in groundwater at Dei-Dei and Kubwa areas of Abuja, north-central Nigeria

The activity concentrations of uranium and toxic elements in Dei-Dei borehole, Kubwa borehole, Water Board and hand-dug well water samples in Abuja area were measured using inductively coupled plasma mass spectrometry (ICP-MS) system. The results obtained were used to calculate human radiological risk over lifetime consumption by the inhabitants in the area. The activity concentrations of 238U in all the water supplies for drinking ranges from 0.849mBqL-1 to 2.699mBqL-1 with the highest value of 2.699mBqL-1 noted at Dei-Dei borehole whereas the lowest value of 0.849mBqL-1 was noted in Kubwa borehole. The highest annual effective dose from natural 238U in all the water samples was found in Dei-Dei borehole with a value of 8.9×10-5mSvy-1 whereas the lowest value was noted in Kubwa borehole with a value of 2.8×10-5mSvy-1. The radiological risks for cancer mortality were found distinctly low, with the highest value of 1.01×10-7 reported at Dei-Dei borehole compared to Kubwa borehole with a value of 3.01×10-8. The cancer morbidity risk was noted higher in Dei-Dei borehole with a value of 1.55×10-7 whereas lower value of 4.88×10-9 was reported in Kubwa borehole. The chemical toxicity risk of 238U in drinking water over a lifetime consumption has a value of 0.006µgkg-1day-1 in Dei-Dei borehole whereas lower value of 0.002µgkg-1day-1 was found in Kubwa borehole. Measured lead (Pb) and chromium (Cr) concentrations reported higher in Water Board compared to Dei-Dei and Kubwa borehole samples. Significantly, this study inferred that the 238U concentrations originate from granitic strata of the tectonic events in the area; thus, there was a trend of diffusion towards north to south and re-deposition towards Dei-Dei area

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