RESUMO
Metal oxide gas sensors with porous structures are widely used in numerous applications ranging from health monitoring and medical detection to safety; in this study, we report a highly sensitive SnO2 gas sensor with a multi-level tube/pore structure prepared via biomimetic technology using flax waste as a bio-template and a simple wet chemical process combined with subsequent annealing. Indeed, MLTPS not only maintained and improved the excellence of porous structure gas sensing materials with abundant active sites and large surface-to-volume ratios, but also overcame the deficiency of the lack of gas diffusion channels in porous gas sensing materials. Thus, this novel multi-level tube/pore SnO2 gas sensor exhibited significantly enhanced sensing performance, e.g. an ultra-low response concentration (250 ppb), a high response (87.9), a fast response (9.2 s), a low operating temperature (130 °C) and good stability, for formaldehyde. On the basis of these results, via the reuse of agricultural waste, this study provides a new concept for the low-cost synthesis of environmentally friendly and effective multi-level tube/pore gas sensor materials.