Preparation Of TiO₂-CeO₂@ZnSnO₃ Composite And The Effect Of UV On Its Gas-sensitivity Performance

Gas sensors which can detect flammable,explosive,toxic and harmful gases are widely used in today's life and production.The performance of gas-sensitive sensors is mainly determined by gas-sensitive materials.Metal oxide semiconductor materials have good photoelectric properties,simple and environmental preparation processes.At present,they have become a hot spot in the field of gas-sensitive sensors.As a ternary metal oxide semiconductor material,ZnSnO3 not only has gas-sensitive performance,but also has UV photoelectric performance.However,when ZnSnO3 is used as a gas-sensitive material,it has some shortcomings,such as high working temperature.It needs to work at more than 200?to show good gas-sensing performance.To solve this problem,the subject adopted the following methods,which not only lowered the working temperature of ZnSnO3,but also improved its gas-sensing performance.First,under the action of the organic functional additive dimethylacetamide(DMAC),co-precipitation method was used to prepare Zn Sn(OH)6 nanospheres(particle size 300-500 nm);second,the above Zn Sn(OH)6was dehydrated at 500?to form ZnSnO₃ nanospheres,and the shape and particle size remained unchanged.Finally,the UV-sensitive materials nano-TiO2(particle size25 nm)and nano-CeO2(particle size 20-50 nm)were used to decorate the ZnSnO3nanospheres to form a heterojunction,and the composite was expose to UV light(wavelength 385 nm).Gas sensitivity test showed that:UV light with a wavelength of 385nm(474 lx)improved the gas-sensing performance of TiO2-ZnSnO3 composite more than UV light with a wavelength of 365nm(420 lx);when the addition proportion of DMAC was 9 wt%,the decoration proportion of nano-TiO2 was 12.5 wt%,and the decoration proportion of nano-CeO2 was 1 wt%,TiO2-CeO2@ZnSnO3 composite was extremely sensitive to ethanol gas under UV light(385 nm),the response was as high as 603(500 ppm),and the working temperature was 100?.The mechanism research shows that the main reason for the improvement of gas sensing performance at low temperature is that:after decoration,nano-TiO2?nano-CeO2 and ZnSnO3 form a heterojunction at the interface,which effectively suppresses the electron-hole recombination.And due to the high illuminance(474 lx),UV light can produce more photoelectrons.These conditions can increase the number of electrons in the conduction band,promote the generation of oxygen anions and gas-sensing reactions,improve the gas-sensing performance of ZnSnO3 at low temperature.In summary,this subject prepared ZnSnO3 nanospheres,which were decorated by nano-TiO2 and nano-CeO2,supplemented by UV light,these actions not only lowered the working temperature of the prepared gas sensor,but also significantly improved the gas response value.The preparation method of TiO2-CeO2@ZnSnO3 composite and the method to improve the gas sensing performance provide new ideas for the research of gas sensor.