Improve the Formaldehyde Gas-Sensing Performance of 3D Porous SnO2 by Controlling the Calcination Time and the Amount of Holmium Doped

Porous SnO 2 with high sensitivity and fast response has attracted much attention. Herein, we prepared 3D porous SnO 2 using carbon balls as a template and studied the effects of sintering time (1 h, 2 h, 3 h, 4 h) at a certain calcination temperature of 500℃ and Ho doping on the gas-sensing performance of 3D porous SnO 2 . The gas-sensing test results show that, compared with the samples obtained under other sintering time, the gas-sensing property of 3D porous SnO 2 calcined for 2 h has the highest gas sensitivity of 31 in the 50-ppm formaldehyde environment. Among the samples doped with Ho, 3D porous SnO 2 with a doping amount of 3.5% has the highest sensitivity of 65 at operating temperature of 230℃, which is twice as long as pure 3D porous SnO 2 with a calcination time of 2 h. Moreover, the sample has good selectivity, low detection limit, and good linearity. These excellent gas-sensing characteristics are mainly due to the unique morphology of 3D porous SnO 2 , more oxygen vacancies, and the influence of Ho doping. Therefore, the gas-sensing performance of the metal oxide semiconductor material can be further improved by forming the porous nanocomposite material. Graphical Abstract (a) Response recovery time of SnO 2 obtained under different calcination times; (b) Response recovery time of SnO 2 doped with different Ho content.