Preparation and Characterization of Developed CuxSn1−xO2 Nanocomposite and Its Promising Methane Gas Sensing Properties

Novel materials with nanostructures are effective in controlling the physical properties needed for specific applications. The use of active and sensing materials is increasing in many applications, such as gas sensing. In the present work, we attempted to synthesize incorporated Cu2+ into the SnO2 matrix as CuxSn1−xO2 nanocomposite using a cost-effective precursor and method. It was observed that, at low concentrations of copper precursor, only SnO2 phase could be detected by X-ray diffraction (XRD). The distribution of Cu in the SnO2 matrix was further measured by elemental analysis of energy-dispersive X-ray (EDX) mapping and X-ray fluorescence (XRF). At high copper concentration, a separated monoclinic phase of CuO was formed (noted here as CuO/SnO2). The average crystallite size was slightly reduced from 5.9 nm to 4.7 nm with low doping of 0.00–5.00% Cu but increased up to 15.0 nm at high doping of 10.00% Cu upon the formation of separated SnO2 and CuO phases. The formation of Cu–SnO2 or CuO phases at low and high concentrations was also observed by photoluminescent spectra. Here, only the emission peak of SnO2 with a slight blueshift was recorded at low concentrations, while only the CuO emission peak was recorded at high concentration. The effect of Cu concentration on the sensing properties of SnO2 toward methane (CH4) gas was also investigated. It was found that the sensor embedded with 2.00% Cu exhibited an excellent sensitivity of 69.0 at 350 °C and a short response–recovery time compared with the other sensors reported here. The sensing mechanism of CuxSn1−xO2 and CuO/SnO2 is thus proposed based on Cu incorporation.