Biomorphic synthesis of 3D mesoporous SnO2 with substantially increased gas-sensing performance at room temperature using a simple one-pot hydrothermal method

Biomorphic SnO2 nanoparticles with a mesoporous structure were synthesized using simple one-step hydrothermal method with SnCl2 as the raw material and hemp stems as the bio-template. The uniformly grown SnO2 nanoparticles perfectly inherited the 3D structure of biomass carbon and formed a rich mesoporous structure, which was beneficial to gas sensing and facilitated the transport of the target gas on the surface and inside the sample. Moreover, the high surface area of materials provides more active sites for the adsorption of oxygen and the target gas. The sample with a 450 °C annealing temperature exhibited an excellent response (35.83) as a NO2 sensor at room temperature (RT), fast response speed to 100 ppm NO2 (2.67 s), and a detection limit as low as 10 ppb. Furthermore, it displayed long-term stability, excellent selectivity and good repeatability. Therefore, the mesoporous biomorphic SnO2 nanoparticles represent a good candidate as a key green material for an NO2 sensor at RT.