Humidity-resistant ethanol gas sensors based on electrospun tungsten-doped cerium oxide hollow nanofibers

Serious interference of humidity limits the wide application of ethanol gas sensors. The transition metal tungsten (W) doped cerium dioxide (CeO2), possessing a hydrophobic nature and rich oxygen vacancies, will tackle the humidity issue. Herein, the pristine and W-doped CeO2 hollow nanofibers were successfully fabricated by electrospinning. Oxygen vacancy content increases first and then decreases with the doping tungsten, and the 1 mol% W-doped CeO2 sample presents the largest content. Further, the 1 mol% W-doped CeO2 sensor exhibits an excellent response of 10.2 to 100 ppm ethanol at 200° C, 3.5 times higher than the pure CeO2 sensor, good selectivity, repeatability, and long-term stability. In addition, the responses of the W-CeO2 sensors are almost humidity independent. The resistances in air and ethanol decrease gradually with the humidity increases, leading to the humidity-resistant response, mainly attributed to the hindered carrier migration by the type-I CeO2/WO3 heterojunction. These results indicate that the appropriate W-doped CeO2 is a potential humidity-resistant gas-sensing material for ethanol sensing.