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In this work, MoS 2 flakes were printed on ceramic substrates and investigated toward 1-10 ppm of nitrogen dioxide (NO 2 ), 2-12 ppm of ammonia (NH 3 ), and 2-12 ppm acetone (C 3 H 6 O) under UV light (275 nm). The structure of overlapping MoS 2 flakes and UV light assistance affected high responsivity to NO 2 when DC resistance was monitored, and superior sensitivity to NH 3 was obtained from the low-frequency noise spectra. MoS 2 exhibited response and recovery times in hundreds of seconds and stability throughout the experiments conducted within a few months. MoS 2 sensor exhibited a resistance drift during the detection of a specific relaxation time. Subtracting the baseline burden with exponential drift exposed the direction of changes induced by oxidizing and reducing gases and reduced DL to 80 ppb, 130 ppb, and 360 ppb for NO 2 , NH 3 , and C 3 H 6 O, respectively. The fluctuation-enhanced sensing (FES) revealed that the adsorption of NO 2 on MoS 2 decreases the noise intensity, whereas adsorbed NH 3 increases the fluctuations of current flowing through the sensor, and these changes are proportional to the concentration of gases. The noise responses for NO 2 and NH 3 were opposite and higher than DC resistance responses with subtracted baseline (an increase of 50% for 10 ppm of NO 2 and an increase of more than 600% for 12 ppm of NH 3 ), showing that FES is a highly sensitive tool to detect and distinguish between these two gases. This way, we introduce a simple and low-cost method of gas sensor fabrication using ink-printed MoS 2 and the possibility of enhancing its sensitivity through data processing and the FES method., (© 2024. The Author(s).)

In this work we study the luminescence properties of europium-doped titanium dioxide and tellurium oxide thin films enhanced by gold plasmonic nanostructures. We propose a new type of plasmon structure with an ultrathin dielectric film between plasmonic platform and luminescent material. Plasmonic platforms were manufactured through thermal annealing of the gold thin film. Thermal dewetting of gold film results in spherical gold nanostructures with average dimensions of 50 nm. Both, luminescent TiO 2 :Eu and TeO 2 :Eu films were deposited by RF magnetron sputtering from mosaic targets. The morphology of the gold nanostructures was investigated by SEM and TEM, while the composition of oxides film was analyzed by XPS. Luminescence properties were studied on the basis of excitation and emission spectra. The experiments show that the additional dielectric layer enhances the luminescence intensity. Such structures could be potential candidates as phosphors in white LEDs., (Copyright © 2021, Łapiński et al.)