SnO₂ Nano/microstructures: Synthesis, Gas Sensor, And Lithium Battery Properties

As an important n-type metal oxide semiconductor, SnO2 is widely used as gas sensing material to detect and monitor the air composition because of its low-cost, high response, fast response-recovery, and good stability. At the same time, SnO2 working as anode material for lithium-ion batteries is widely investigated for its high capacity. For those reasons, we focus on SnO2 as the research object and first investigate its gas sensing performance. Au nanoparticles was utilized to improve its gas sensing performance. Besides, SnO2 was also investigated as lithium-ion batteries anode material. The main results are as follows:1、Hydrothermal synthesis of SnO2 micro/nano porous three-dimensional(3D) structure and its gas sensing performance(1) SnO2 micro/nano porous three-dimensional structures was prepared with hydrothermal method. The pore size distributing on the nanosheet surfaces is in the range of 2~ 50 nm and the BET specific surface area is determined to be 62.5 m2/g. Gas sensing performance revealed that the sensor is capable to detect target gas with concentration in the range of 5 ~ 200 ppm. Fast response-recovery was also obtained even the sensor was aged under high temperature for a long time.(2) In order to improve the gas sensing performance of 3D SnO2 microstructure, Au nanoparticles with diameters ranging from 5 to 10 nm were immobilized on the surface of nanosheets under the help of lysine. Gas sensing tests show that Au/SnO2 has better performance than prinstine SnO2. Eespecially, the response and recovery time is greatly reduced from 6/29 s to 5/10 s, respectively.(3) In order to demonstrate the improving performance of caused by Au nanoparticle loading, ZnO nanorods was chosen as raw material and gas sensing properties were compared between ZnO and Au/ZnO. It is proved that Au nanoparticles also significantly improve the properties of ZnO nanorods under the same test conditions. Au/ZnO has high sensitivity, fast response and recovery, good stability. And it also exhibits good linearity in a wide concentration from 2 to 1000 ppm.2. Preparation of SnO2 hollow spheres with template(1) SiO2 microspheres were synthesized through the hydrolysis of TEOS and SnO2 wascoated on SiO2 with hydrothermal method. SiO2 template was etched and SnO2 hollow spheres of different diameters were obtained. The BET specific surface area test revealed the specific surface area increases with their diameter decreases. Gas sensing performance tests show that higher sensitivity was obtained with SnO2 hollow spheres of larger specific surface area. Due to the incomplete removal of insulating Si O2 template, it influences the performance of hollow spheres. So, Au nanoparticles were loaded on SnO2 hollow spheres with the help of lysine and gas sensing performance was significantly improved, especially for the better stability. Response increases with the increase of Au content.3. Preparation of TiO2@SnO2 core-shell microstructure and its lithium performanceSnO2 and TiO2 as anode materials for lithium-ion batteries both have disadvantages.SnO2 has poor cycle performance and TiO2 has low capacity. TiO2, SnO2 spheres and TiO2@SnO2 core-shell spheres were synthesized, respectively. The weight content of SnO2 is53.44% while TiO2 is 41.56%, and the theoretical capacity of TiO2@SnO2 is 496 mAh/g.TiO2@SnO2 core-shell has improved cycling performance compared with SnO2. Due to the solid spheres with large size, larger volume effect was happened during charge and discharge process and result in serious capacity loss.