Pyrochlore cerium stannate (Ce2Sn2O7) for highly sensitive NO2 gas sensing at room temperature

Gas sensing at low temperatures remains a notable challenge at present. Owing to their strong catalytic activity, oxygen defects, and unique size, pyrochlore-based oxides have attracted considerable attention for preparing conductometric gas sensors that are effective at low temperatures. In this study, we prepared a pyrochlore-Ce2Sn2O7 structure using a facile hydrothermal method. The structure, morphology, and surface valance states of the prepared sample were analyzed. Additionally, we investigated the gas-sensing properties, such as the selectivity, response, response and recovery time, repeatability, stability, limit of detection, and influence of relative humidity on the sensing performance for NO2 gas molecules at room temperature (30 +/- 2 degrees C). The Ce2Sn2O7 exhibited outstanding selectivity for NO2 gas molecules compared with the interfering gas molecules such as N2O, CO, CO2, SO2, NH3,NO and H2S at room temperature (30 +/- 2 degrees C.). Moreover, the response and recovery time values were 4 s and 52.5 s, respectively, and an outstanding response of 125% was achieved toward 50 ppm NO2 gas molecules. The Ce2Sn2O7 sensor device exhibited excellent repeatability and stability over 90 days. The excellent gas-sensing performance was attributable to the high specific surface area, presence of oxygen vacancies, and surface-adsorbed oxygen molecules.