Enhanced gas sensing performance of tin oxide thin films by plasma jet-assisted cobalt oxide nanoparticle decoration
摘要
A major challenge in SnO2-based NO2 gas sensors is their limited sensitivity and selectivity at low operating temperatures. To address this, the present work employs plasma jet-assisted Co3O4 nanoparticle decoration as a simple, low-cost, and scalable strategy to enhance gas- ensing performance. In this study, tin oxide (SnO2) thin films were prepared at 400 °C temperature by a simple spray pyrolysis. The films were then decorated with cobalt oxide (Co3O4) nanoparticles using an atmospheric plasma jet at different exposure times (5 and 10 min). X-ray diffraction (XRD) of the bare films revealed the coexistence of SnO2 and SnO phases with variations in crystallite size observed after the nanoparticle decoration. Films exposed to a longer plasma treatment (10 min) exhibited an additional Co3O4 phase, confirming the successful deposition of cobalt oxide nanoparticles. FE-SEM images indicate the surface modifications by the appearance of nanoparticles whose number density increased with decoration time. FTIR spectra displayed the characteristic bands of tin oxide along with new absorption bands attributed to cobalt oxide. Optical absorption spectra demonstrated a red shift in the absorption edge following nanoparticle deposition. Gas-sensing measurements revealed a notable enhancement in NO2 response after decoration, with the best performance achieved at a 5-min exposure time. The optimized sample exhibited a maximum sensitivity of nearly twice that of the pristine film toward 60-ppm NO2 at 200 °C, while longer decoration times reduced performance. These results confirm the effectiveness and simplicity of atmospheric plasma jet nanoparticle decoration for environmental monitoring applications.