Nonlinear optical studies of Oligomers dyades of polyphenylene using Open aperture z-scan technique

National audienc

Nonlinear optical studies of Oligomers Anisole dyades by Open-aperture z-scan technique

International audienc

Visible-light driven sonophotocatalytic removal of tetracycline using Ca-doped ZnO nanoparticles

Highly efficient, long-term, eco-friendly catalysts for water decontamination technology are urgently needed to meet the prioritized objectives of green development and societies worldwide. Ca-doped ZnO were investigated as environmentally friendly sono-photocatalytic system under LED visible light irradiation to efficiently mineralize tetracycline-based antibiotics. The effects of pH, Ca doping, light, ultrasound, and pH on the mineralization of tetracycline by Ca-doped ZnO nanopowders and on the chemical, sono-, photo- and sono-photostability of Ca-doped ZnO nanopowders were systematically investigated. The ZnO-based catalyst with 2 at. % of Ca dopant exhibited the best sono-photocatalytic performance in mineralizing tetracyclines under visible LED light and ultrasound irradiation (i.e., 99% mineralization in 90 min), with excellent reusability and minimal sono-photocorrosion (i.e., 1% of catalyst dissolution in 180 min), which were even greater in the absence of organic pollutants and in the pH range of most natural waters. For Ca-doped ZnO nanopowders, the role of the generated reactive oxygen species under light and ultrasound stimulation and the mechanism of the mineralization of tetracycline were analyzed. In conclusion, the sono-photocatalytic mineralization of antibiotics synergizing visible LED light and weak ultrasound irradiation in the presence of Ca-doped ZnO nanopowders presents an outstanding start to developing highly efficient, long-term, eco-friendly catalysts for efficiently treating emerging organic pollutants

CO sensing characteristics of In-doped ZnO semiconductor nanoparticles

Abstract A study on the CO sensing characteristics of In-doped ZnO semiconductor nanoparticles (IZO NPs) prepared by a modified sol–gel technique is reported. The morphological and microstructural features of IZO NPs with various dopant concentrations (1 at.%, 2 at.%, 3 at.%, and 5 at.% In) were investigated by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). The influence of indium doping on defect characteristics of ZnO was also investigated by photoluminescence (PL). A thick film of IZO NPs was deposited by screen printing on an alumina substrate provided with a pair of Pt interdigitated electrodes to fabricate a simple conductometric sensor platform. The as fabricated In-doped ZnO sensors showed enhanced sensitivity to CO gas with respect to pure ZnO one. Sensors with low dopant loading (1 at.% and 2 at.% In) were found to be more sensitive with shorter response and recovery times than those with high dopant loading

Optical limiting efficiency of an electroactive bis-iminopyridine ligand and its zinc complex

An electroactive based bis-iminopyridine ligand has been synthesized by a condensation reaction between (4-(6,7-dimethyldithio-tetrathiafulvalene)-aniline) with 2,6-diformylpyridine. The complexation of this ligand with ZnCl2 afforded a tetrahedral neutral Zinc metal complex. Nonlinear optical measurements of these structures have given good results in picosecond regime. The nonlinear absorption of the ligand was significantly enhanced upon complexation with ZnCl2. This prompted us to conduct the experiment of optical limiting at wavelength 532nm. The nonlinear absorption properties of these structures were studied and compared to the reference material C60

Optical limiting efficiency of an electroactive bis-iminopyridine ligand and its zinc complex

An electroactive based bis-iminopyridine ligand has been synthesized by a condensation reaction between (4-(6,7-dimethyldithio-tetrathiafulvalene)-aniline) with 2,6-diformylpyridine. The complexation of this ligand with ZnCl2 afforded a tetrahedral neutral Zinc metal complex. Nonlinear optical measurements of these structures have given good results in picosecond regime. The nonlinear absorption of the ligand was significantly enhanced upon complexation with ZnCl2. This prompted us to conduct the experiment of optical limiting at wavelength 532nm. The nonlinear absorption properties of these structures were studied and compared to the reference material C60

Morphology-Controlled Aluminum-Doped Zinc Oxide Nanofibers for Highly Sensitive NO2 Sensors with Full Recovery at Room Temperature

Room-temperature (RT) gas sensitivity of morphology-controlled free-standing hollow aluminum-doped zinc oxide (AZO) nanofibers for NO2 gas sensors is presented. The free-standing hollow nanofibers are fabricated using a polyvinylpyrrolidone fiber template electrospun on a copper electrode frame followed by radio-frequency sputtering of an AZO thin overlayer and heat treatment at 400 degrees C to burn off the polymer template. The thickness of the AZO layer is controlled by the deposition time. The gas sensor based on the hollow nanofibers demonstrates fully recoverable n-type RT sensing of low concentrations of NO2 (0.5 ppm). A gas sensor fabricated with Al2O3-filled AZO nanofibers exhibits no gas sensitivity below 75 degrees C. The gas sensitivity of a sensor is determined by the density of molecules above the minimum energy for adsorption, collision frequency of gas molecules with the surface, and available adsorption sites. Based on finite-difference time-domain simulations, the RT sensitivity of hollow nanofiber sensors is ascribed to the ten times higher collision frequency of NO2 molecules confined inside the fiber compared to the outer surface, as well as twice the surface area of hollow nanofibers compared to the filled ones. This approach might lead to the realization of RT sensitive gas sensors with 1D nanostructures

CO-sensing Properties of Potentiometric Gas Sensors Using an Anion-conducting Polymer Electrolyte and Au-loaded Metal Oxide Electrodes

CO-sensing properties of potentiometric gas sensors using an anion-conducting polymer (ACP) as an electrolyte and metal oxides loaded with and without Au as electrodes (EC(MO) or EC(nAu/MO(Tm)), respectively, MO: metal oxide (In2O3, ZnO or Co3O4), n: the loading amount of Au, 0.5?2.0 wt%, T: heat-treatment temperature, m: heat-treatment atmosphere, air or H2) have been investigated in wet synthetic air (57%RH) at 30 °C. In addition, H2-sensing properties of these sensors have also been investigated in the same gaseous conditions, to evaluate their CO selectivity against H2. All of the EC(MO) sensors showed relatively small changes in electromotive force (EMF), i.e. responses, to both CO and H2, but the Au loading to In2O3 and ZnO drastically improved the magnitude of CO response of the EC(In2O3) and EC(ZnO) sensors, respectively. The EC(2.0Au/In2O3(400air)) sensor showed larger CO response, faster CO response speed, excellent CO selectivity against H2 and better long-term stability than those of the EC(2.0Au/ZnO(400air)) sensor. The influence of moisture on the CO response of the EC(2.0Au/In2O3(400air)) sensor was almost negligible in the humidity range of 40?100%RH. The magnitude of CO response of the EC(2.0Au/In2O3(400air)) sensor in wet synthetic air showed a good linear relationship with CO concentration, but the CO response was largely affected by the concentration of O2. These results indicate that the EMF of the EC(2.0Au/In2O3(400air)) sensor is probably determined by the mixed potential resulting from CO oxidation and O2 reduction. The heat-treatment conditions of the 2.0 wt% Au-loaded In2O3 powder largely affected the CO-sensing properties of the EC(2.0Au/In2O3(Tm)) sensors. Among these sensors heat-treated in various conditions, the as-fabricated EC(2.0Au/In2O3(250H2)) sensor showed the most excellent CO selectivity against H2 in their concentration range of 10?3000 ppm

Synthesis, Characterization and Sensing Properties of AZO and IZO Nanomaterials

Al-doped ZnO (AZO) and In-doped ZnO (IZO) nanopowders were prepared by a sol-gel route and subsequent drying in ethanol under supercritical conditions. The morphological and microstructural properties were investigated by transmission electron microscopy (TEM) analysis and X-ray powder diffraction (XRD). The characterization study showed that the AZO and IZO nanoparticles were crystalline and exhibited the hexagonal wurtzite structure. Chemoresistive devices consisting of a thick layer of synthesized nanoparticles on interdigitated alumina substrates have been fabricated and their electrical and sensing characteristics were investigated. The sensor performances of the AZO and IZO nanoparticles for carbon monoxide (CO) were reported. The results indicated that both doped-sensors exhibited higher response and quick response/recovery dynamics compared to a ZnO-based sensor. These interesting sensing properties were discussed on the basis of the characterization data reported