Template-assisted mesoporous SnO 2 based gas sensor for NO 2 detection at low temperature

The work outlines the synthesis of mesoporous tin oxide (m-SnO 2 ) with enhanced Nitrogen Dioxide (NO 2 ) gas sensing performance by making use of Cetyl Trimethyl Ammonium Bromide (CTAB) as the soft template. Powder X-ray Diffraction (PXRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FTIR) spectroscopy and X-ray Photoelectron Spectroscopy have been used to study the structural characteristics of mesoporous tin oxide. The average crystallite size calculated from the XRD technique was found to be 4.8 nm which is in corroboration with TEM analysis (4.9 nm). The FESEM indicated the porous morphology of the prepared sample which was also confirmed by N 2 adsorption–desorption isotherms. The surface area and the average pore size of the sample were calculated from Brunauer–Emmett–Teller (BET) studies and Barrett–Joyner–Halenda (BJH) method and were found to be 154.4 m 2 g −1 and 3.2 nm, respectively confirming the mesoporosity of the prepared tin oxide. The sensor was prepared by deposition of m-SnO 2 thin film on Inter Digited Electrodes (IDE’s) of platinum decorated on a glass substrate. 10 parts per million concentration of oxidizing gas NO 2 was tested on the fabricated sensor in the temperature range, 30 °C to 160 °C. Upon interacting with the gas, the sensor exhibited a response of 8635 with response time of 1s and recovery time of 165 s at 80 °C. The efficient sensor performance at 80 °C as observed in the present study is at much lower temperature in comparison with those reported earlier. The sensor has further shown good repeatability in terms of response and recovery at 80 °C. The sensor also exhibited good reproducibility and selectivity for NO 2 gas. The enhanced sensor response of mesoporous tin oxide sensor is mainly because of large surface area (154.4 m 2 g −1 ), mesoporous structure and small crystallite size (4.8 nm). The present study therefore establishes m-SnO 2 as a potential candidate for efficient sensing of NO 2 gas.