Facile Hydrothermal Synthesis of SnO₂ Nanoflowers for Low-Concentration Formaldehyde Detection

In this work, SnO₂ nanoflowers were prepared by a simple one-step hydrothermal process. The morphology and structure of SnO₂ nanoflowers were characterized by SEM, TEM, Raman spectroscopy, and XRD, which demonstrated the good crystallinity of the SnO₂ tetrahedron structure of the as-synthesized materials. In addition, the sensing properties of SnO₂ nanoflowers were studied in detail. It was found that the SnO₂ nanoflower-based gas sensor exhibits excellent gas response (9.2 to 120 ppm), fast response and recovery (2/15 s to 6 ppm), good linearity of correlation between response (S) vs. concentration (C) (lgS = 0.505 lgC - 0.147, R² = 0.9863), superb repeatability, and selectivity at 300 °C. The outstanding performance can also be attributed to the high specific surface area ratio and size of SnO₂ nanoflowers close to the thickness of the electron depletion layer that can provide abundant active sites, promote the rate of interaction, and make it easier for gas molecules to diffuse into the interior of the material. Therefore, SnO₂ nanoflowers can be an ideal sensing material for real-time monitoring of low-concentration HCHO.