The Design Of Co₃O₄ And In₂O₃ Composite System For Gas Sensing Applications

Gas sensing devices are widely used in industrial production,laboratory experimentation and public transport.It has attracted more attention to detect the concentration of different volatile organic compounds(VOCs)around us.However,there still remain some imperfections of traditional sensing materials such as the complex synthesis process,the sensitivity of sensing devices and the relatively high operating temperature.Thus,it's also necessary to improve the performance of traditional sensing materials.In this dissertation,the Co3O4-In2O3 heterojunction structure was successfully prepared via a simple calcination method without any surfactants or templates.Structure characterization shows the samples are formed with cubic phase of Co3O4 and In2O3 nanoparticles.This unique structure can change the distribution of carriers at the interface between n-and p-type semiconductors which will lead to the improvement of ethanol sensing performance.It is found that the Co3O4-In2O3 heterojunction structure with 1 wt%Co3O4 shows greatly high gas response to ethanol.The response is 62.13,which is 1.36 times higher than pure In2O3 and 11.6 times higher than pure Co3O4.Besides,it's also efficient to improve ethanol sensing performance by noble metal load.We deposited Ag nanoparticles in the surface of the flower-like cubic In2O3 via a room temperature water bath deposition.The sensitivity of this kind of ethanol sensing devices is improved which can be attributed to the catalytic performance of Ag nanoparticles.The results show that In2O3-Ag(1%)exhibits the highest sensing performance.The response is 70.2,which is 1.56 times higher than pure In2O3.Finally,when it comes to cubic p type Co3O4 semiconductors,the response values can be greatly improved by silver loading via a simple room temperature deposition.Moreover,the optimum working temperature of Co3O4-Ag(5%)nanocomposite system can be decreased from 260? to 100 ?,which has great advantages in reducing the cost of detecting and simplifying the assembling technology of sensing devices.