| Nanomaterials have received extensive attentions,because of its unique properties and excellent performances in the past twenty years.Experimental methods for synthetizing of advanced materials and detecting the micro-mechanism of chemical reactions are limited,but first principles density functional theory is used to understand the properties of materials based on atomic and molecular level and design the new materials,and it has become a very important research method with the development of computer level.It is great significance for understanding the mechanism of low-nanomaterials catalytic reactions and designing novel composite catalysts by the theoretical calculations.We apply the first principles based on densityfunctional theory to study the interactions between boron nitride nanosheets and metals and related applications.This paper consists of four chapters.The first chapter mainly introduces the background of research,the second chapter introduces the theoretical research methods and its development.The density functional theory is based on quantum mechanics,that is from the density of the study system to solve the density of the ground state particles and obtain the properties of systems.It is achieved by solving the Kohn-Sham equation to simplify the interaction of a number of particle problems.Finally,the ground state energy of system is obtained by the self-consistent iterative solution of the ground state charge density.In the third chapter,by first-principle methods,the stability and electronic structure of iron nanoparticle anchored on defective boron nitride nanosheet were investigated.It is found that the defect sites such as boron and nitrogen vacancy significantly increase the adsorption energies of Fe13,suggesting that the supported Fe13 nanoparticles should be very stable against sintering at high temperatures.From the calculated density of states,we testify that the strong interaction is attributed to the coupling between the 3d orbitals of Fe atoms with the sp2 dangling bonds at the defect sites.The Bader charge and differential charge density analyses reveal that there is significant charge redistribution at the interface between Fe13 and the substrates,leading to positive charges located on most of the Fe atoms.Additionally,our results show that the strong binding of the nanoparticle results in the upshift of d-band center of Fe13 towards the Fermi level,thus making the surface Fe atoms with higher reactivity.This work provides a detailed understanding the interaction between Fe13 nanoparticle and defective h-BNNS and will provide helpful instructions in the design and synthesis of supported Fe-based catalysts in heterogeneous catalysis.In the fourth chapter,the reaction mechanism of carbon monoxide with boron nitride nanosheet supported on copper was studied.A Cu(111)supported h-BN nanosheet(h-BNNS)has been systematically investigated by first-principle DFT with dispersion corrections.During the interaction between Cu and h-BNNS,the electrons migrate from the metal to h-BNNS,leading to the formation of gap states above and under the Fermi level.Significant electrons are observed to mitigate from the supported h-BNNS to the O2 molecule,resulting in the activation of the adsorbed O2.While for the unsupported h-BN,the absorbed O2 is almost intact w:ith a very weak binding energy.CO oxidation is chosen as a benchmark probe reaction to better understand the enhanced catalytic activity induced by Cu(111)metal substrate.The calculated energy barrier of the reaction CO + O2*-*CO2*+ O*is found to be only 0.51 eV with a large exothermicity of-2.93 eV.Even for the process of CO reacting with the residual atomic O*to generate CO2*,the barrier is found to be nearly null,helping the catalyst facilely recovers itself.Our calculation results suggest that Cu(111)supported h-BNNS is a potential low cost and high activity catalysts for CO oxidation. |
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