Gas Sensing Behavior Of Pd And Ag Doped InN

In the field of gas sensing,the two-dimensional InN(Indium Nitride)monolayer material is a six-atom cyclic planar structure composed of three In(Indium)atoms and three N(Nitrogen)atoms staggered from each other.Being Comparing with its hexagonal wurtzite corresponding with its bulk structure,the two-dimensional InN monolayer has a larger surface-to-volume ratio,which makes it material more abundant in physical and chemical properties.In order to enhance the sensing performance of the intrinsic two-dimensional InN monolayer material,being doping with transition metal atoms is an effective methodology to optimize its adsorption and electronic properties.The noble metal Ag(Silver)and Pd(Palladium)atoms have strength adsorption capacity and chemical reaction rate for certain gas molecules.So,the thesis uses transition metal(TM)Ag atoms and Pd atoms as surface dopants to enhance the adsorption and sensing properties of the two-dimensional InN monolayer.In this dissertation,we investigated into the sensing capabilities of a two-dimensional InN monolayer for environmentally harmful gases(such as,SO₂ and NO)and flammable and explosive gases(H₂),based on density functional theory in the framework of first-principles.It notes that the adsorption energy,band structure,density of state(DOS,Total DOS and Partial DOS),charge difference and bader charge of the adsorption system were carried out by theoretical calculation study,which mainly insight to the interaction between the adsorbent surface and adsorbate molecules,such as,the forbidden band width and the intensity of charge transfer.We separately compared the band structure,charge difference and bader charge,as adsorbing before and after gas molecules,which doped with InN monolayer and co-doped InN monolayer,respectively.In the case of adsorbing gas molecules(e.g.,SO₂,NO and H₂),the InN monolayer of the occurrence of a large amount of charge transfer mainly leads to significant changes in the electronic structure of the system,which in turn affects other properties of the system.For each doping system,the recovery time and sensitivity of each system are excellent when the temperature is about 400K.The Ag-InN system is more suitable for the detection of H₂ molecules.The Pd-InN system has the best performance when detecting SO₂ molecules,and the transition metal Ag atoms and Pd atoms co-doped InN monolayer(Ag Pd-InN)have better gas sensitivity when detecting H₂ molecules.From the perspective of each gas molecule,when detecting SO₂ molecules,the Pd-InN system has higher conductivity and stronger charge transfer in the above all systems.When detecting NO and H₂ molecules,the co-doped InN monolayer(Ag Pd-InN)is more sensitive than Ag atoms doped InN(Ag-InN)alone,the recovery time is shorter and the adsorption structure is more stable.In the adsorption of H₂ molecular of the co-doped InN system of Ag atoms and Pd atoms,Pd atoms has a strong catalytic effect in adsorption,and it occupies a dominant position in the competition with Ag atoms;in terms of electronic properties,Ag atoms have a strong catalytic effect and also Pd dominates the atomic competition.Ag atoms and Pd atoms separately doped with different doping content in InN monolayer system can indeed change the physical and chemical properties of the adsorption system.It is worthwhile to note that the co-doped InN adsorption gas molecules(i.e.,SO₂,NO,and H₂)systems can significantly enhance the N-type conductivity or P-type conductivity of the two-dimensional InN monolayer,which following by the changes of doping content.