Preparation Of Iron Oxide/copper Oxide Composites And Their Gas Sensing Properties

Gas sensors have received great attentions in the detection of toxic,explosive,flammable and harmful gases over the last decades,owing to their irreplaceable merits such as simple industrial production,low cost,easy integration,compact size and low power consumption.After decades of development,gas sensor has been widely used in industry,agriculture,medical and health diagnostic.Compared with the single metal oxide gas sensor,the multi-metal oxide has the advantages of low operating temperature,good selectivity,stable performance and low detection limit.Among various mental oxide-semiconductors,copper oxide ferrite(CuFe₂O₄)has recently aroused widespread concerns owing to its superior physical and chemical properties.Inspite of the encouraging preliminary results,systematic research on the sensing performance of CuFe₂O₄ is relatively rare and the reported sensing properties was rather far to satisfy the practical application.Development and performance optimization of CuFe₂O₄ gas sensor is of great significance to promote the application of high-performance gas sensor.Focusing on the performance optimization of CuFe₂O₄ material,our work mainly carried out the following three aspects based on different preparation methods:(1)CuFe₂O₄ particles were successfully synthesized by co-deposition method.The effects of SDBS concentration of surfactant,stirring speed and reaction time on the sample morphology and gas-sensitive performance were investigated comprehensively.The experimental results indicated that SDBS showed an obvious effect on the crystal shape during crystal growth.The octahedral CuFe₂O₄ particles with the best gas-sensitive performance were achieved when the SDBS concentration was 6 times as its critical micelle concentration,the reaction time was 3 h,and the stirring rate was 1000 rpm.Further deep analysis,suggested the CuFe₂O₄ particles exhibited excellent detection performance for H₂S gas with the detection limit 125 ppb at 100?.In addition,the material also presented good cyclic stability and moisture resistance.(2)Fe₂O₃/CuO two-dimensional porous array films were obtained by using polystyrene spheres(PS spheres,with 500 nm diameter)as templates.Our investigation found that(Fe₂O₃/CuO)composite film displayed good sensing properties to ethanol molecules,with a minimum detection limit of 5 ppm at 100?.In addition,the morphology and properties of two-dimensional porous films can be further optimized by adjusting the metal salt ratio of Fe/Cu and their concentrations in the precursor salt solution.(3)CuFe₂O₄ powder was prepared by sol-gel method,with glucose as additiyities to control the morphology.When the concentration of glucose was 0.25 mol/L,the CuFe₂O₄ exhibited the optimal gas sensing performance,towards NO₂ with the detection limit of 500 ppb at 50?.