ENHANCEMENT IN UV SENSING PROPERTIES OF Zno:Ag NANOSTRUCTURED FILMS BY SURFACE FUNCTIONALIZATION WITH NOBLE METALIC AND BIMETALLIC NANOPARTICLES

In this study, Ag-doped ZnO (ZnO:Ag) nanostructured films were functionalized with silver nanoparticles (Ag NPs), silver-platinum bimetallic nanoparticles (AgPt NPs) and silver-gold bimetallic NPs (AgAu NPs) using a gas phase PVD process based on a Haberland type gas aggregation cluster source and unipolar DC planar magnetron sputtering. Ultraviolet (UV) sensing investigations showed arespectable time constants reduction for rising and decaying photocurrents, as well as an increase for the UV response. Compared to a pristine nanostructured film the surface functionalization with Ag, AgPt and AgAu increased the UV response by factors of 2.7, 3.5 and 4, respectively. The increased performances of the here presented ZnO:Ag nanostructured films functionalized with monometallic and bimetallic NPs based photodetectors are explained by the increased lifetime of photogenerated electron –hole pairs, as well as the formation of nanoscale Schottky barriers at the interface of Au/ZnO:Ag and Pt/ZnO:Ag

3rd International Conference on Nanotechnologies and Biomedical Engineering

This volume presents the proceedings of the 3rd International Conference on Nanotechnologies and Biomedical Engineering which was held on September 23-26, 2015 in Chisinau, Republic of Moldova. ICNBME-2015 continues the series of International Conferences in the field of nanotechnologies and biomedical engineering. It aims at bringing together scientists and engineers dealing with fundamental and applied research for reporting on the latest theoretical developments and applications involved in the fields. Topics include Nanotechnologies and nanomaterials Plasmonics and metamaterials Bio-micro/nano technologies Biomaterials Biosensors and sensors systems Biomedical instrumentation Biomedical signal processing Biomedical imaging and image processing Molecular, cellular and tissue engineering Clinical engineering, health technology management and assessment; Health informatics, e-health and telemedicine Biomedical engineering education Nuclear and radiation safety and security Innovations and technology transfer

Copper Doped Zinc Oxide Micro- And Nanostructures For Room-Temperature Sensorial Applications

Detection of hydrogen gas is important for safety reasons. To obtain improved hydrogen sensing performances for miniaturized sensors, copper doping in zinc oxide micro- and nanostructures were investigated. Samples were grown by hydrothermal technique at relatively low temperature and studied by X-ray diffraction, micro-Raman, SEM and sensorial techniques. It is found evidence on the improvement of the sensorial properties due to copper-doping in zinc oxide rods-like structures. © 2013 IEEE

Effect of noble metal functionalization and film thickness on sensing properties of sprayed TiO2 ultra-thin films

International audienc

TiO2/Cu2O/CuO Multi-Nanolayers as Sensors for H2 and Volatile Organic Compounds: An Experimental and Theoretical Investigation

TiO2/Cu2O/CuO multi-nanolayers highly sensitive toward volatile organic compounds (VOCs) and H2 have been grown in various thicknesses by a cost-effective and reproducible combined spray-sputtering-annealing approach. The ultrathin TiO2 films were deposited by spray pyrolysis on top of sputtered-annealed Cu2O/CuO nanolayers to enhance their gas sensing performance and improve their protection against corrosion at high operating temperatures. The prepared heterostructures were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and ultraviolet visible (UV-vis) and micro-Raman spectroscopy. The gas sensing properties were measured at several operating temperatures, where the nanolayered sensors with oxide thicknesses between 20 and 30 nm (Cu2O/CuO nanolayers) exhibited a high response and an excellent selectivity to ethanol vapor after thermal annealing the samples at 420 °C. The results obtained at an operating temperature of 350 °C demonstrate that the CuO/Cu2O nanolayers with thicknesses between 20 and 30 nm are sensitive mainly to ethanol vapor, with a response of ∼150. The response changes from ethanol vapors to hydrogen gas as the thickness of the CuO/Cu2O nanolayers changes from 50 to 20 nm. Density functional theory-based calculations were carried out for the geometries of the CuO(1¯ 11)/Cu2O(111) and TiO2(111)/CuO(1¯ 11)/Cu2O(111) heterostructures and their sensing mechanism toward alcohols of different chain lengths and molecular hydrogen. The reconstructed hexagonal Cu2O(111) surface and the reconstructed monoclinic CuO(1¯ 11) and TiO2(111) facets, all of which terminate in an O layer, lead to the lowest surface energies for each isolated material. We studied the formation of the binary and ternary heteroepitaxial interfaces for the surface planes with the best-matching lattices. Despite the impact of the Cu2O(111) substrate in lowering the atomic charges of the CuO(1¯ 11) adlayer in the binary sensor, we found that it is the different surface structures of the CuO(1¯ 11)/Cu2O(111) and TiO2(111)/CuO(1¯ 11)/Cu2O(111) devices that are fundamental in driving the change in the sensitivity response observed experimentally. The experimental data, supported by the computational results, are important in understanding the use of the multi-nanolayered films tested in this work as reliable, accurate, and selective sensor structures for the tracking of gases at low concentrations