Biotemplate-inherited porous SnO2 monotubes with oxygen vacancies for ultra-high response and fast detection of nitric oxide at low temperature

How to construct low-temperature nitric oxide sensors with fast detecting speed and high sensing response remains challenging. To this end, we simply immersed the waste willow catkins in SnCl4 solution, and then calcined the precursors to controllably prepare biotemplate-inherited SnO2 sensing materials. Amongst, the monotubes (marked as SnO2-6) obtained by calcination at 600 °C are cross-linked by small-size nanoparticles, and have homogeneous distribution of mesopores, large specific surface area and rich oxygen vacancies. Synergistic effect of these advantageous structure characteristics greatly accelerates the rapid diffusion of gas molecules in sensing layer, and exposes more surface-active sites to promote their adsorption and chemical reaction, thus ultra-highly and rapidly monitoring NO at low temperature. At 92 °C, SnO2-6 sensor exhibits large response value of 2533 towards 10 ppm NO, which is 15.73 times higher than that of SnO2-7 material. Its response/recovery times are shortened to 49 s/13 s. Meanwhile, it still possesses small practical limit of detection, satisfactory selectivity, long-term stability and moisture resistance. Furthermore, the sensing mechanism was analyzed in detail.