Ga-doped 3D ordered porous SnO2 with an ultrasmall pore size for enhanced formaldehyde sensitivity

Pure and Ga-doped 3 D ordered porous SnO2 (3DOPS) and SnO2 nanoparticles (NPs) were prepared. The 3DOPS/3% Ga-based sensor exhibits an improved response (61/50 ppm) to formaldehyde (HCHO), and the response is 3 times higher than pure 3DOPS (21/50 ppm) at low temperature (220 °C). However, the response of SnO2 NPs/3% Ga (10/50 ppm) is only 1.25 times that of the pure SnO2 NPs (8/50 ppm). Regardless of the SnO2 morphology, doping with Ga can improve its response. However, after the 3 D ordered porous structure of SnO2 doped with Ga element, its response is improved more obviously than that of the particle structure of SnO2. This may be attributed to the combined effect of the construction of the three-dimensional ordered porous structure and the doping elements.