Synthesis Of Zn₂SnO₄-ZnO Composites And Their Gas Sensing Properties

Zn2SnO4-ZnO is a kind of important composite oxide semiconductor material,which has excellent performance than single oxide material in some application fields.In addition,it can be achieved to regulate the merits of its performance effectively by changing the component compared with single oxide material Recently,the research of Zn2SnO4-ZnO composites as a gas sensing material was mainly focused on detecting alcohols,NO2,and so on.Zn2SnO4-ZnO composite material was synthesized by the carbon-assisted thermal evaporation method in this work,the purpose is to obtaine Zn2SnO4-ZnO composites that have good crystallinity,small size,and high yield through optimizing preparation conditions,which will be applied in gas sensors for gas sensitive characteristic research.The mixture of SnO2,ZnO,and active carbon powders was used as the source materials,and Au-coated Si substrates were used as the substrate material Zn2SnO4-ZnO composites were prepared by thermal evaporation method under different experimental conditions.In addition,experimental conditions were optimized according to the characterization results of XRD,SEM,and EDS.The results show that Zn2SnO4-ZnO composites with good crystallinity,small size,and high yield can be obtained under the conditions of reaction temperature of 1000?,reaction time of I h,SnO2,ZnO and C with the molar ratio of 2:1:4,and O2 content in the mixed gas of 3%.Moreover,Zn2SnO4-ZnO composites obtained under the optimal experimental conditions were further observed and analyzed by TEM and FTIR.Gas sensors were fabricated by dispersing the Zn2SnO4-ZnO composites on the planar Au electrodes.The sensing properties were investigated to H2 by mixing detected gas and air in static state.The results show that Zn2SnO4-ZnO composites show significant response and recovery properties to H2,which have short response and recovery times.The highest response of Zn2SnO4-ZnO composites to H2 is found at an operating temperature of 300?.The response of Zn2SnO4-ZnO composites to detected gas continuously increases with increasing H2 gas concentrations.Comparing with the characterizations of VLS and VS growth mechanisms,as well as according to the characterization results of SEM and TEM,it can be concluded that Zn2SnO4-ZnO composites grow via VS growth mechanism The growth process of Zn2SnO4-ZnO composites is simulated according to SEM images.Based on the response and recovery properties of Zn2SnO4-ZnO composites to H2 gases,it shows that Zn2SnO4-ZnO is a kind of n-type semiconductor material.The gas sensing mechanism indicates that it mainly depends on the surface reaction between the detected gas and adsorbed oxygen ions on the surface of the material and subsequently the changes in electrical resistance of gas sensor.