NiO/SnO ₂ heterostructure 2D-thin films for detection of SO ₂ gas

In the present research work, RF sputtered SnO ₂ thin film overcast with NiO as a catalyst has been exploited to design SO ₂ gas sensors. NiO nanoclusters of varying thickness on the film’s surface of SnO ₂ as a catalyst. Microstructural analysis of pristine SnO ₂ thin film depicted porous and cracked surface morphology and regular and homogeneous distribution of grains was observed for SnO ₂ thin film integrated with NiO catalyst. The gas sensing response of prepared thin films was explored against various gases such as sulfur dioxide (SO ₂ ), liquified petroleum gas (LPG), Methane, Acetone, and carbon dioxide (CO ₂ ). SnO ₂ thin film gas sensor having thin 10 nm NiO nanoclusters exhibited an enhanced sensing response of ~54. The sensor produces a response time of 75 s and a recovery time of 60 s, respectively at a lower 180 °C operating temperature. A gas-sensing method for an improved fast-sensing response has been presented following the addition of a catalyst for the NiO/SnO ₂ gas sensor. This work demonstrates the first systematic optimization of NiO nanocluster thickness (6–14 nm) on SnO ₂ thin films, revealing that 10 nm NiO nanoclusters provide optimal surface roughness and dual-mechanism sensing and achieve 2.16 times higher sensing response than state-of-the-art Ag-doped WO₃ sensors while operating at 220 °C lower temperature.