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

Porous SnO2 with high sensitivity and fast response has attracted much attention. Herein, we prepared 3D porous SnO2 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 SnO2. The gas-sensing test results show that, compared with the samples obtained under other sintering time, the gas-sensing property of 3D porous SnO2 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 SnO2 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 SnO2 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 SnO2, 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. (a) Response recovery time of SnO2 obtained under different calcination times; (b) Response recovery time of SnO2 doped with different Ho content.