ITO Material Adsorption Of First-principles Simulation And Precious Load On Its Adsorption Properties

This dissertation calculated and simulated the ITO gas sensitive materials and the CO、 NO adsorption property by the first principle, it also calculated and simulated the ITO loaded noble metal and the CO、 NO adsorption property. ITO loaded Pd was prepared by the method of mechanical alloying and solid phrase sintering. The analyzing phase and microscopic constitutions were analyzed by XRD、 SEM and EDS. In addition, we studied gas sensing properties of ITO loaded Pd for adsorbing CO.Since the In2O3content was above90%in ITO. The most stable structure was found to be the In2O3(11o) by comparing with surface energy of5low index surface of In2O3(In203(100) In203(100)-2、In203(100)、In2O3(111) and In2O3(111).2). The surface of In203(110) was a highly probable in crystal growing. In this thesis, the CO and NO adsorptive property of In203(110) doped with Sn was simulated based on In203(110).As a result of Sn doped, active sites were changed from O to the place of Sn doped and selectivity were changed to gas about ITO. From density of states, the first layer of atoms had made an important contribution to ITO adsorbing CO, but only the first layer could have made a contribution to ITO adsorbing NO near fermi level.The paper simulated models of ITO loaded Pt and Pd for studying the effect of adsorptive property for CO or NO based on before-mentioned simulation. The results showed ITO(110) loaded Pt or Pd and the adsorption of CO or NO on the ITO(110) loaded Pt or Pd were spontaneous processes. Comparing with ITO(110), adsorption energy of CO or NO on the ITO(110) loaded Pt or Pd were reduced. This suggested that it was affecting the sensitivity of ITO on gas by Pt and Pd loading. The analysis of the result of experiment showed that the noble metal was comported with composition design loaded on the surface of ITO material. The analysis of SEM and EDS showed dispersive distribution of Pd was located in surface of porous ITO and it was a kind of cluster structure. The analysis of gas-sensitivity measurement showed the sensitivity of ITO was improved by Pd loading.Compared simulative results with experimental results, they had the deviation between gas sensitivity of ITO adsorbing CO by Pt and Pd loading. The reasons showed as follows. The loading of Pd was a kind of doping process in experiments. But, the loading of Pd was a kind of adsorption process in simulation. The loading content of simulation was different from experiment. Such a model was simple to design because noble metal clusters were represented by an atom. The metal clusters were evenly dispersed in surface of porous ITO in experiment that was many different from simulates.