Graphitic carbon-doped SnO2 nanosheets-wrapped tubes for chemiresitive ppb-level nitric oxide sensors operated near room temperature

The development of low-temperature metal oxide-based sensors with high sensing response towards harmful ppb-level gases remains challenging. Based on the idea of biological structure imitation, we choose wooden hydrangea petals as biotemplate and carbon source to controllably replicate graphitic carbon-doped SnO2 material (GC/SnO2-6) by simply calcining the salt solution-soaked precursor at 600 °C. Its morphology is tube bundle wrapped by corrugated sheets that formed by cross-linkage of nanoparticles. The internal surface of tube wall is decorated with nanoaggregates. The fabricated GC/SnO2-6 sensor exhibits response value of 256.3 towards 1 ppm NO at 50 ℃, which is 9.9 times higher than that (S = 26.0) of pure SnO2-7 material obtained by calcining at 700 ℃ in air. Meanwhile, this sensor also has short recovery time (42 s), low actual detection limit (50 ppb), satisfactory moisture resistance and long-term stability. Such excellent comprehensive gas-sensing performance is attributed to the homogeneous mesopore and large specific surface area of its biomorphic structure, as well as the synergism of graphitic carbon doping and abundant oxygen vacancies. In addition, the enhanced sensing mechanism is also explored in detail.