@misc{MańkowskaMazurDomaradzkietal., author = {Mańkowska, Ewa and Mazur, Michał and Domaradzki, Jarosław and Mazur, Piotr and Kot, Małgorzata and Flege, Jan Ingo}, title = {Hydrogen Gas Sensing Properties of Mixed Copper-Titanium Oxide Thin Films}, series = {Sensors}, volume = {23}, journal = {Sensors}, number = {8}, issn = {1424-8220}, doi = {10.3390/s23083822}, abstract = {Hydrogen is an efficient source of clean and environmentally friendly energy. However, because it is explosive at concentrations higher than 4\%, safety issues are a great concern. As its applications are extended, the need for the production of reliable monitoring systems is urgent. In this work, mixed copper-titanium oxide ((CuTi)Ox) thin films with various copper concentrations (0-100 at.\%), deposited by magnetron sputtering and annealed at 473 K, were investigated as a prospective hydrogen gas sensing material. Scanning electron microscopy was applied to determine the morphology of the thin films. Their structure and chemical composition were investigated by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The prepared films were nanocrystalline mixtures of metallic copper, cuprous oxide, and titanium anatase in the bulk, whereas at the surface only cupric oxide was found. In comparison to the literature, the (CuTi)Ox thin films already showed a sensor response to hydrogen at a relatively low operating temperature of 473 K without using any extra catalyst. The best sensor response and sensitivity to hydrogen gas were found in the mixed copper-titanium oxides containing similar atomic concentrations of both metals, i.e., 41/59 and 56/44 of Cu/Ti. Most probably, this effect is related to their similar morphology and to the simultaneous presence of Cu and Cu2O crystals in these mixed oxide films. In particular, the studies of surface oxidation state revealed that it was the same for all annealed films and consisted only of CuO. However, in view of their crystalline structure, they consisted of Cu and Cu2O nanocrystals in the thin film volume.}, language = {en} } @misc{KapuścikWojcieszakPokoraetal., author = {Kapuścik, Paulina and Wojcieszak, Damian and Pokora, Patrycja and Mańkowska, Ewa and Domaradzki, Jarosław and Mazur, Michał and Mazur, Piotr and Kosto, Yuliia and Morales, Carlos and Kot, Małgorzata and Flege, Jan Ingo}, title = {Low temperature hydrogen sensor with high sensitivity based on CeOx thin film}, series = {Sensors and Actuators B: Chemical}, volume = {417}, journal = {Sensors and Actuators B: Chemical}, publisher = {Elsevier BV}, issn = {0925-4005}, doi = {10.1016/j.snb.2024.136148}, pages = {12}, abstract = {In this work, a 500 nm-thick cerium oxide thin film was prepared by electron beam evaporation. It was found that the deposition of 7 nm thick Pd catalyst was required for obtaining a sensor response to hydrogen. The Pd/CeOx sensing structure has a high response of 5000 towards 25 ppm H2 at a working temperature of 200 °C and exhibits a sensor response of 1.3 at temperatures near ambient. Furthermore, the sensing structure exhibited excellent response/recovery kinetics. The results confirm that the CeOx-based materials are a promising material for the fabrication of room-temperature hydrogen sensors.}, language = {en} } @misc{KostoKapuscikTschammeretal., author = {Kosto, Yuliia and Kapuscik, Paulina and Tschammer, Rudi and Guttmann, Dominic and Mankowska, Ewa and Matvija, Peter and Morales, Carlos and Mazur, Michał and Henkel, Karsten and Matolinova, Iva and Domaradzki, Jarosław and Flege, Jan Ingo}, title = {Bare and Pd-doped ceria thin films prepared by ALD and EBE for hydrogen detection}, series = {Verhandlungen der DPG}, journal = {Verhandlungen der DPG}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {The need to store and use hydrogen safely as part of green economy based on renewable energy evokes a necessity to reliably detect it at ambient conditions. The majority of currently used sensors are working at elevated temperatures (200-500 °C). In this work, we demonstrate that ceria films deposited on a commercial electrode by atomic layer deposition (ALD) and electron beam evaporation (EBE) electrically respond to hydrogen (from 20 to 500 ppm) at much lower temperatures (50-200 °C). The results reveal that <1.5 nm thin Pd adlayer increases the electrical response by several orders of magnitude for both ceria films. The NAP-XPS study under changing oxidative/reductive atmospheres sheds light on the mechanism of Pd-CeOx thermal activation and the role of the deposition technique in the reactivity of the oxide.}, language = {en} }