Temperature-controlled dual-selectivity nitric oxide/acetone sensor constructed from mesoporous SnO2 tubes doped by biomass-derived graphitic carbon

How to achieve good dual-functional selectivity of metal oxide-based sensors to harmful gases remains challenge due to few relevant reports. To this purpose, we selected waste willow catkins as structure-oriented template and carbon source to controllably prepare biomorphic GC/SnO2-500 sensing material by air calcination of 500 °C. Its tubular morphology is cross-linked by 3.51 wt% biomass-derived graphitic carbon (GC) and small-size nanoparticles. It has relatively large specific surface area, uniform mesopore distribution and rich oxygen vacancies. The synergistic effect of above positive factors promotes the rapid gas transport to sensing layer, and also increases the reactive sites and its resistance modulation ability, thus achieving good dual-functional selectivity. At 92 °C, GC/SnO2-500 sensor displays large response value of 802 to 10 ppm NO, and exhibits a good response towards 100 ppm acetone at 217 °C (S = 22). Both of the indexes are better than those of most corresponding gas sensors reported presently. Meanwhile, the sensor has short response time, satisfactory long-term stability and humidity tolerance. Moreover, portable temperature-dependent dual-functional gas-sensing mechanism is also discussed.