First-principles Study On The Adsorption Behavior And Catalytic Process Of CO On CeO₂?111? Surface

With the continuous development of human science and technology and the continuous advancement of society,the problem of environmental pollution has become increasingly serious and has affected the normal life of mankind.On the one hand,cars have become an indispensable tool for human travel,and a large number of cars emit a large amount of exhaust gas,which contains harmful gases such as CO.On the other hand,factories and power companies burn coal and produce a large amount of CO.Therefore,the adsorption and catalytic oxidation of carbon monoxide has become a hot topic.Precious metals have long been the ideal oxidation catalyst for CO,but due to the high cost of precious metals,non-precious metal catalysts have been developed.Among them,cerium oxide CeO₂ catalyst has been widely concerned and applied by virtue of its excellent catalytic activity for oxidizing CO,and has become the best carrier for catalytic oxidation of CO.Therefore,the physical properties and adsorption behavior of CO adsorption on CeO₂ surface were studied,and the catalytic oxidation process of CO on CeO₂ surface was simulated.Firstly,based on the first-principles calculation,the basic properties of the K-point value,lattice constant,maximum cut-off energy and surface energy of CeO₂?111?cells are determined,which provides the accurate parameters of the adsorption of CO on the surface of CeO₂?111?.Then,the adsorption behavior of CO on the surface of CeO₂ was observed by comparing the adsorption of CO on different adsorption sites on the surface of CeO₂ of 3 O-Ce-O layer 2×2 supercells,and the optimal adsorption position of CO was preliminarily determined.In this paper,we compare the adsorption behavior of CO on the surface of CeO₂ with different layers and different supercellular structures to study the influence of the number of layers of CeO₂ and the structure of supercellular structure on CO adsorption,and select the appropriate number of CeO₂ layers and the supercellular structure CO adsorption for in the next study.Secondly,in the case where CO adsorbs on the surface of CeO₂ to form CO₂ and form oxygen vacancies,this paper studies the different positions of Ce³⁺by moving the surface oxygen atoms of CeO₂ toward oxygen vacancies to transfer charge and change the position of Ce³⁺to study the relationship between the different position of Ce³⁺and the adsorption energy of CO.The results show that the adsorption energy of CO is the lowest when Ce³⁺is in the next position of oxygen vacancies.Then,by studying the relationship between the position of Ce³⁺on the surface of CeO₂ with oxygen vacancies and the formation energy of oxygen vacancies,the influence of the relative position of Ce³⁺and oxygen vacancies on the energy of the system is further verified.Thirdly,the study found that CO can adsorb to form CO₃^2-carbonate on the basis of adsorption of CO₂,and the adsorption energy of CO is further reduced.Subsequently,the adsorption process and adsorption energy difference between CO forms a bond with CeO₂ surface oxygen atoms and subsurface O atoms were studied.Finally,we can see that the lowest adsorption energy state of CO is CO forms a bond with two surface O atoms in the form of carbonate.The formation process of CO to CO₂ to CO₃^2-was demonstrated by the neb method.Finally,by comparing the adsorption behavior of CO on the surface of CeO₂undoped and doped with precious metals Pd and Cu,the mechanism of the reaction activity and catalytic reaction of noble metals is verified more intuitively and effectively.Then,this paper studies about CO is adsorbed on the surface of CeO₂ by CO,O₂adsorbs on the surface of CeO₂ with oxygen vacancies and CO adsorbs to form CO₂after O₂ adsorption.The cyclic oxidation process of CO on the surface of CeO₂ is presented.