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In the presented work, the influence of cationic precursor molarity on supercapacitive, photocatalytic and LPG-sensing performance of CdO thin films synthesized by successive ionic layer adsorption and reaction method has been investigated. An attempt has been made to correlate the observed properties with structure and morphology of the deposited films. Structural characterization using XRD indicates an increase in crystallite size from ~ 12.3 to ~ 25.6 nm with increasing molarity of Cd2+ precursor solution from 0.1 M to 0.3 M, beyond which there is a reverse tendency. Band gap energy decreases from 2.22 to 2.04 eV with increasing molarity of Cd2+ precursor solution from 0.1 M to 0.3 M. For further increase of molarity to 0.4 M, the band gap energy increases to 2.08 eV. Thin film CdO electrode deposited from 0.3 M cadmium nitrate solution shows maximum specific capacitance of 228 Fg−1 at a voltage scan rate of 2 mVs−1 measured from cyclic voltammetry (CV) measurements. Charging–discharging measurements show maximum specific capacitance of 220 Fg−1 at a current density of 1 Ag−1. Capacitance retentivity of 96.5% after 5000 cycles was exhibited by the above said thin film electrode. Films deposited from 0.3 M Cd2+ content precursor solution also show improved photocatalytic activity as well as gas-sensing property in presence of LPG. The highest degradation of methyl orange dye of 76.2% under exposure to visible light of 200 W energy and maximum sensitivity of 78% in presence of 1000 ppm LPG at an operating temperature of 260 °C were observed. [ABSTRACT FROM AUTHOR]

CuO thin films were successfully deposited using a simple, cost-effective and nearly room-temperature successive ionic layer adsorption and reaction routes. The material has been characterized using x-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy. Increase of grain size and decrease of microstrain were observed for a particular level of dipping (30 cycles) and further increase in dipping cycles shows a reverse tendency. The effect of the dipping cycle of the synthesized films on their supercapacitive, photocatalytic and ethanol-sensing performance were investigated. A 30-cycle dipped CuO thin film-based electrode provides a maximum specific capacitance of 585 Fg−1 at the voltage scan rate of 2 mVs−1 from cyclic voltammetry measurement and 554 Fg−1 at a current density of 1 Ag−1 from the charging to discharging curve. This electrode exhibited long-term cycle stability with 92.3% capacitance retention after 4000 cycles. CuO films synthesized for 30 dipping cycles showed the highest photocatalytic activities with 91.1% degradation of methylene blue under exposure to visible light of 200-W energy in a time duration of 4 h. Maximum sensitivity of 67% in the presence of 1500 ppm ethanol at the operating temperature 160°C was obtained for 30 dipping cycles film. Such attractive properties of low cost and facile synthesized CuO thin films makes them a suitable candidate for different commercial applications. [ABSTRACT FROM AUTHOR]

In this report, we have primarily studied the influence of nickel (Ni) incorporation on ac electrical conductivity, dielectric relaxation mechanism and impedance spectroscopy characteristics of copper oxide (CuO) thin films synthesized by successive ion layer adsorption and reaction (SILAR) technique. The materials has been characterized using X-ray diffraction and UV-VIS spectrophotometric measurements. Reduction in grain size in doped films up to a certain extent of doping (tentatively 6%) were confirmed from XRD analysis, beyond which there is a reverse tendency. Increase in band gap in doped films were observed up to 6% doping level which could be associated with enhanced carrier density in doped films. Impedance spectroscopy analysis confirmed enhancement of ac conductivity and dielectric constant for doped samples. The results are useful for capacitive application of the films. Beyond 6% doping level, AC conductivity and dielectric constant shows a reverse tendency indicating reduced density of charge carriers. Nyquist plot shows contribution of both grain and grain boundary towards total resistance and capacitance. Imaginary part of complex modulus and imaginary part of complex impedance was used to find the migration/activation energy to electrical conduction process. Nearly identical result was obtained from relaxation frequency/relaxation time approach suggesting hopping mechanism of charge carriers. Successful incorporation of Ni in CuO thin film through SILAR technique.Reduction of grain size and enhancement of band gap up to 6% Ni incorporation.Enhancement of ac conductivity and dielectric constant up to 6% Ni incorporation.Reverse tends in structural, optical and electrical characteristics beyond a certain doping level.Contribution of both grain and grain boundary towards total resistance and capacitance. [ABSTRACT FROM AUTHOR]