Synthesis of nanostructured cubic phase SnO₂ thin film and its trace-level sensing of CO gas

In this study, we report the fabrication of a cubic phase SnO₂-based thin film gas sensor with excellent sensitivity and selectivity for carbon monoxide (CO) gas at room temperature, with a high response of 25606% achieved at 2 ppm CO gas concentration, and a detection limit down to 1 ppb. Cubic phase SnO₂ thin films are synthesized using a simple sol-gel process, followed by spin coating. Our synthesis technique allows for stabilizing the cubic phase of SnO₂, confirmed through XRD and TEM studies, which is otherwise reported at high pressures and temperatures. Further, our DFT simulations show that the cubic phase of SnO₂ nanoparticles has a lower energy barrier for CO adsorption and desorption than the more common tetragonal phase. The low-voltage and ambient operating conditions of the sensor reported in this study make it highly practical for widespread use, thus offering a promising solution to the growing need for efficient and affordable gas sensing applications, including environmental monitoring, industrial safety, and medical diagnosis.