The First Principle Study Of Nitrogen Oxide Adsorption Reaction On Tungsten Trioxide

With the rapid development of industrial automation,the demand for traditional fuels is increasing day by day.In order to govern emissions and effective detect the gas concentration,gas detector came into being,their basic principle is: A series of physical and chemical changes caused by the adsorption of gas molecules on the surface of the detector are converted into electrical signals.The experimental results could not explain the rapid reaction process.We use simulation software to study the mechanism of gas sensitivity of NO and NO₂ molecules on the surface of WO₃.By studying the adsorption equilibrium structure and electron transfer of gas molecules at different adsorption sites,the gas sensitivity mechanisms of NO and NO₂ molecules on the surface of WO₃ were revealed.By searching the transition state and describing the energy change of the reaction path,we can deeply understand the catalytic oxidation process of NO molecules on the WO₃ surface.We hope to indicate the direction of experimental research with theoretical results.Theoretical research results are as follows:1.In this chapter,the adsorption of NO molecules on two different sections of WO₃?001?was studied,we also consider the effect of oxygen deficiencies on adsorption.The adsorption results show that NO has the best performance of adsorption on WO-WO₃?001?'s surface with oxygen vacacies.The presence of oxygen deficiency increases the WO₃'s sensitivity to NO.On the WO-WO₃?001?surface,the oxygen deficient surface is more than the complete surface with multiple transfer 0.24 e.2.In this chapter,the adsorption of NO₂ molecules on two different sections of WO₃?001?was studied.Our calculations show that the bridging oxygen atom on an oxygen defect on an O-terminated WO₃?001?surface is the active site where a NO₂ molecule is oxidized into nitrate and is adsorbed onto the surface.On a WO-terminated?001?surface,one of the oxygen atoms from the NO₂ molecule fills the oxygen vacancy,and the resulting NO fragment is adsorbed onto a W atom.Both of these adsorption models can cause an increase in the electrical resistance of WO₃.3.In this chapter,we study the coverage of NO molecules for the catalytic oxidation of NO molecules on the surface of WO atoms.In the case of high coverage of NO molecules,NO molecules tend to react with oxygen atoms on the WO₃ surface and produce adsorbed states of NO₂,which will leads to the formation of oxygen vacancy.In the case of low coverage,the oxygen molecules adsorbed on the surface of WO₃ were dissociated into oxygen atoms,and the NO molecules react with adsorbed oxygen atoms.So the coverage of NO molecules will affect the reaction process.