Research On Gas Sensing Properties And Their Influencing Factors Of SnO₂ Based Gas Sensors

Analysis of gases dissolved in transformer oil is one of the most efficient way to diagnose faults of oil-immersed power transformer in the early stages.Gas sensing detection technology plays a key role in this area since its simple structure,low requirement of maintenance and cheap price.It is quite significant in terms of both theoretical and engineering aspects to make continuous research on sensing mechanism to achieve a higher level of online detection technology and enhanced reliability of running transformer.In this paper,it carried out gas sensing properties research on pure and doped SnO₂ based gas sensor for H₂,CO,C₂H₂ gases under various circumstances.SnO₂ based gas sensors were fabricated to conduct a series of experiments to measure their gas sensing properties.Then,based on the density functional theory and first-principles theory,pure and doped SnO₂surface models and H₂,CO,C₂H₂absorption models were built.Finally,the gas sensing mechanism was studied from both experimental and simulating perspectives.The main innovative achievements are as follows:?1?Based on the density functional theory and first-principles theory,pure and doped SnO₂?110?surface models and H₂,CO,C₂H₂ absorption models were established for simulating calculations.Meanwhile,density of states and charge distribution were calculated for micro level research.It indicates that doped SnO₂ based gas sensor has more desirable gas sensing properties,including response-working current,response-concentration,response-recovery features.Furthermore,ZnO doped sensors have better performance than Pd doped ones.?2?Pure,Pd and Zn O doped SnO₂materials were synthesized by using hydrothermal route.Materials'phase,crystal structure,morphology and element composition were examined via XRD,SEM,TEM,XPS and EDS.?3?Pure and doped SnO₂based gas sensors for H₂,CO,C₂H₂ gases were fabricated to conduct a serial of feature experiments including response-working current,response-concentration,response-recovery,response-humidity characteristics under normal and humid circumstance.It suggested that doped SnO₂ based gas sensor has better gas sensing properties comparing to pure SnO₂ based one.In addition,ZnO doped sensors outperformed Pd doped ones in terms of response-working current,response-concentration,response-recovery time and resistance of humidity.?4?Based on the experimental data analysis of gas-sensing materials,the experimental results of gas-sensing characteristics of SnO₂-based gas sensor under different doping methods are in good agreement with the simulation results,which proves that the first-principles analysis method of density functional theory supports the experiment,Also shows that the experimental steps in this design and experimental data acquisition is effective.On the basis of this,the performance of the gas-sensing under different environmental humidity was further tested.The experimental results show that the moisture resistance of the doped material is improved,and the metal oxide doping is better than the pure metal.The experiment designed in this paper provides a new idea and research method for the further study of gas sensing mechanism.