Loofah sponge-templated synthesis of multilayered mesoporous SnO₂ with excellent NO₂ detection performance at low temperatures

Nitrogen dioxide is a hazard to the natural environment and human health. Therefore, it is necessary to design a nitrogen dioxide sensor to detect NO 2 . In this work, using SnCl 2 as the raw material and loofah sponge as the bio-template, SnO 2 -bio was synthesized through simple immersion and calcination, inheriting the multilayer mesoporous structure of the bio-template. Compared to commercially available SnO 2 , this material has a larger specific surface area and offers more oxygen vacancies for the reaction with adsorbed gases. At 92℃, the SnO 2 -bio sensor exhibits a higher response value of 247.6–5 ppm NO 2 . Meanwhile, it has faster response and recovery speeds of 65/43 s, respectively. The SnO 2 -bio sensor also has excellent selectivity, long-term stability, and cycling stability. Furthermore, in-situ techniques and density functional theory were employed to investigate the mechanism of sensitization and the effect of oxygen vacancies on gas adsorption.