Y₂O₃-modified nio nanocomposite thick films for low-temperature ethanol sensing applications

Abstract

NiO and Y₂O₃–NiO nanocomposites with varying Y₂O₃ concentrations (1–11 wt%) were synthesized through a hydrothermal route followed by thermal treatment, and thick film sensors were fabricated using a conventional screen-printing technique for gas sensing applications. Structural, morphological, compositional, and optical properties of the prepared materials were systematically characterized using XRD, FESEM, EDS, FTIR, and UV–Visible spectroscopy. XRD confirmed successful incorporation of Y₂O₃ into the NiO matrix without secondary impurity phases, while FESEM revealed morphology evolution toward porous interconnected structures with increased active surface sites. Gas sensing studies were performed toward ethanol, H₂S, NH₃, methanol, NO₂, and CO₂ gases over an operating temperature range of 25–100 °C. Pristine NiO exhibited preferential response toward H₂S, whereas Y₂O₃ incorporation gradually modified the sensing characteristics and produced a higher response toward ethanol among the investigated gases. Among all compositions, the 5 wt% Y₂O₃–NiO nanocomposite exhibited the highest response (∼88.09%) toward 250 ppm ethanol at an optimum operating temperature of 70 °C, along with response and recovery times of approximately 19 s and 18 s, respectively, and good stability over six weeks. The enhanced sensing performance is attributed to the combined effects of optimized morphology, increased adsorption-active sites, and improved interfacial interaction. These findings demonstrate the potential of Y₂O₃–NiO nanocomposites for ethanol sensing applications.