Template-synthesized SnO₂ Hierarchical Structure And Its NO₂ Sensitive Properties

Nitrogen dioxide(NO₂)has been considered as major source of air pollution,which can not only bring about acid rain,haze and many other serious environmental problems,but also cause respiratory disease,cardio-vascular disease and even cancer.At present,most reported low-temperature SnO₂-based gas sensors suffered from the defects of low response,slow recovery and poor selectivity to NO₂ gas,thus limiting their practical application.Hence,it's still a challenging work to achieve ultra-high response and rapid recovery of SnO₂-based sensing materials towards NO₂ at low energy consumption.In this thesis,diverse SnO₂ hierarchical structures(including Sn_CB-600 fibers,multi-porous Sn_BS-600 microtubules and mesoporous Sn_PB-600 microtubules)were synthesized via a simple immersion-calcination method using waste filter cigarette butts(CB),bean sprouts(BS)and poplar branches(PB)as template.Meanwhile,TG,IR,Raman,XRD,SEM,TEM,XPS,UV-Vis,EPR techniques were uesd to characterize composition,structure and phase of synthesized materials.The impact of calcination temperature on microstructure and gas-sensing performance of SnO₂products was also investigated.In addition,we also investigated gas-sensing mechanism in details.The results showed that mesoporous Sn_PB-600 microtubules obtained from poplar branches bio-template exhibited ultra-high response value of 3411 to 10 ppm NO₂ gas at 50? with recovery time being as short as 17 s.The actual detection limit was lower to 100ppb.All these indexes are better than most reported SnO₂-based NO₂gas sensors at low temperature.Therefore,Sn_PB-600 sensor has potential application for high sensing and rapid detecting trace NO₂ gas at low energy consumption.