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ACS Appl Mater Interfaces

Title:		TiO(2)/Cu(2)O/CuO Multi-Nanolayers as Sensors for H(2) and Volatile Organic Compounds: An Experimental and Theoretical Investigation
Author(s):		Lupan O; Santos-Carballal D; Ababii N; Magariu N; Hansen S; Vahl A; Zimoch L; Hoppe M; Pauporte T; Galstyan V; Sontea V; Chow L; Faupel F; Adelung R; de Leeuw NH; Comini E;
Address:		"Functional Nanomaterials, Faculty of Engineering, Institute for Materials Science, Kiel University, Kaiserstrasse 2, D-24143 Kiel, Germany. Center for Nanotechnology and Nanosensors, Technical University of Moldova, 168 Stefan cel Mare si Sfant Boulevard, MD-2004 Chisinau, Republic of Moldova. Department of Physics, University of Central Florida, Orlando, Florida 32816-2385, United States. School of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom. Faculty of Engineering, Chair for Multicomponent Materials, Christian-Albrechts Universitat zu Kiel, Kaiserstrasse 2, D-24143, 16 Kiel, Germany. Institut de Recherche de Chimie Paris-IRCP, Chimie ParisTech, Paris Sciences et Lettres (PSL) Universite, rue Pierre et Marie Curie 11, 75231 Paris, France. Sensor Laboratory, Department of Information Engineering (DII), University of Brescia, Via Valotti 9, 25133 Brescia, Italy. National Center for Biomedical Engineering, Technical University of Moldova, 168 Stefan cel Mare si Sfant Boulevard, MD-2004 Chisinau, Republic of Moldova. Department of Nanoelectronics and Surface Modification, Sumy State University, 2 Rymskogo-Korsakova Street, 40007 Sumy, Ukraine. Department of Earth Sciences, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, The Netherlands"
Journal Title:		ACS Appl Mater Interfaces
Year:		2021
Volume:		20210705
Issue:		27
Page Number:		32363 - 32380
DOI:		10.1021/acsami.1c04379
ISSN/ISBN:		1944-8252 (Electronic) 1944-8244 (Linking)
Abstract:		"TiO(2)/Cu(2)O/CuO multi-nanolayers highly sensitive toward volatile organic compounds (VOCs) and H(2) have been grown in various thicknesses by a cost-effective and reproducible combined spray-sputtering-annealing approach. The ultrathin TiO(2) films were deposited by spray pyrolysis on top of sputtered-annealed Cu(2)O/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 (Cu(2)O/CuO nanolayers) exhibited a high response and an excellent selectivity to ethanol vapor after thermal annealing the samples at 420 degrees C. The results obtained at an operating temperature of 350 degrees C demonstrate that the CuO/Cu(2)O nanolayers with thicknesses between 20 and 30 nm are sensitive mainly to ethanol vapor, with a response of approximately 150. The response changes from ethanol vapors to hydrogen gas as the thickness of the CuO/Cu(2)O nanolayers changes from 50 to 20 nm. Density functional theory-based calculations were carried out for the geometries of the CuO(1?a11)/Cu(2)O(111) and TiO(2)(111)/CuO(1?a11)/Cu(2)O(111) heterostructures and their sensing mechanism toward alcohols of different chain lengths and molecular hydrogen. The reconstructed hexagonal Cu(2)O(111) surface and the reconstructed monoclinic CuO(1?a11) and TiO(2)(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 Cu(2)O(111) substrate in lowering the atomic charges of the CuO(1?a11) adlayer in the binary sensor, we found that it is the different surface structures of the CuO(1?a11)/Cu(2)O(111) and TiO(2)(111)/CuO(1?a11)/Cu(2)O(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"
Keywords:		Cu2O CuO TiO2 multilayered films nanolayers nanomaterials p-type sensor;
Notes:		"PubMed-not-MEDLINELupan, Oleg Santos-Carballal, David Ababii, Nicolai Magariu, Nicolae Hansen, Sandra Vahl, Alexander Zimoch, Lukas Hoppe, Mathias Pauporte, Thierry Galstyan, Vardan Sontea, Victor Chow, Lee Faupel, Franz Adelung, Rainer de Leeuw, Nora H Comini, Elisabetta eng 2021/07/06 ACS Appl Mater Interfaces. 2021 Jul 14; 13(27):32363-32380. doi: 10.1021/acsami.1c04379. Epub 2021 Jul 5"