| Recently, alloy nanometer catalysts play an increasingly important role in the field of catalysts, based on large specific surface, lots of controllable factor, and synergic effects of metals. They are used for solving energy and environment problems, thus researchers on catalytic materials get more attention for alloy nanometer catalyst. In research methods, the calculations based on density functional theory (DFT) has become a popular method for researching nanometer catalyst. It is confirmed in the accuracy of the method. Here, we research alloy nanometer catalysts by molecular simulation and density functional theory (DFT) calculation and explain the structures and catalytic performance in specific reactions of Pd-Pt, Cu-Ni and Au-Pd alloy nanometer catalysts systematically. The work of this paper can be divided into three sections. In the first section, structures, thermal stability, and chemical activity of the specific crown-jewel-structured Pd-Pt nanoalloys are studied by molecular simulation and DFT calculation. In the second section, the role of composition and geometric relaxation in CO2 binding to Cu-Ni bimetallic clusters are researched by DFT calculation. In the third section, DFT calculation was used to research the interaction of metal cluster-functionalized ionic liquids (ILs) and CO2. The conclusions of this paper are as follows.(1)The equilibrium structures of different cluster clusters sizes'(55, 147,309 and 561) crown-jewel (CJ)-structured Pd-Pt nanoalloys with highly symmetric cuboctaheral (Cubo), decahedral (Dec), and icosahedral (Ico) structures are obtained by using Monte Carlo (MC) simulation. Compared with the total energy per atom of these nanoalloys, the stability of CJ-structured Pd-Pt nanoalloys with the same size follows the order of Ico> Dec>Cubo. The melting points of CJ-structured Pd-Pt nanoalloys with the same size follow the order of Ico> Dec> Cubo by molecular dynamics (MD) simulations. The DFT calculation confirms For the CJ-structured Pd12Pt43, the adsorption strength of O follows the order of Dec< Cubo< Ico, and the adsorption strength per O atom decreases slightly with increasing coverage of the O atom. In addition, the adsorption strength of O on the CJ-structured Pd12Pt43 is stronger than that on the CJ-structured Pd12Pt135. The research in this paper for structures, thermal stability, and chemical activity of the crown-jewel-structured Pd-Pt nanoalloys will provide theoretical basis for the design of CJ-structured nanoalloys as catalysts.(2) The equilibrium structures of 55-atom Cu-shell, Ni-core nanoalloys (Cu55, Cu54Ni1, Cu42Ni13) with highly symmetric cuboctaheral (Cubo), decahedral (Dec), and icosahedral (Ico) structures are obtained by DFT calculation. It is found that the stability orders:Ico> Dec> Cubo by comparing average binding energy. Meanwhile, the adsorption ability of Cu42Ni13 is strongest due to the highest adsorption energy of CO2 on the top site. In addition, the structural transformation from Cubo and Dec to Ico clusters upon CO2 adsorption, which is agree with the stability law. This paper shows the role of composition and geometric relaxation in CO2 binding to Cu-Ni bimetallic clusters, which can provide useful insights for the design and development of Cu-Ni bimetallic clusters used for methanol synthesis via CO2 hydrogenation.(3) Au, Pd metal cluster-functionalized ionic liquids is designed by DFT calculations. It is found that the catalysts are stable and also enhance the adsorption strength of CO2. Changing single Au or Pd atom into metal clusters, and the strongest adsorption energy of CO2-is found on the composition of Au1Pd2 cluster-functionalized ILs. This paper shows that the adsorption properties of CO2- on Au-Pd cluster-functionalized ILs with different composition and size of the cluster, which can provide a new idea for the design and development of metal cluster-functionalized ILs for the conversion of CO2. |
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