Support Effect For The Structure Of Palladium/Gold And The Performance Of The Direct Synthesis Of H₂O₂ By Hydrogen And Oxygen

Supported palladium and gold catalysts based on MXene and metal oxides have been widely used in petrochemical,environmental,and energy fields.The support not only provides the basic mechanical properties of supported metal catalyst,but also regulates the structure of the metal active component,the morphology of the metal,and its catalytic performance.The support-metal interface can provide the additional active site for some reaction processes.Thereofre,based on the multisimulation method combined by the density functional theory?DFT?and molecular dynamics?MD?,the work firstly studies the support for the regulation of palladium and gold morphology based on the two-dimensional materials MXene?Mo₂C?.The calculations of electronic properties revealed the intrinsic mechanism of palladium and gold structure transformation,which provides the guidance for the design and synthesis of metal-supported catalysts.The geometry and electronic structure of palladium gold on the surface of functionalized Mo₂C were studied through multiscale simulation to effectively control the structure of supported palladium and gold.Based on the DFT calculations,the anatase TiO₂ supported palladium catalyst was used to adjust the reaction performance of the direct synthesis of H₂O₂.And the main method is modifying the TiO₂ surface by oxygen vacancies and carbon-doped oxygen vacancies.Then,the effect of palladium supported on the modified TiO₂?101?surface for the synthesis performance of H₂O₂ was studied and predicted.The main findings are as follows:1.As the support directly affects the metal structure and active site distribution,combining multiscale simulations of DFT and MD,the geometric and electronic structure of palladium and gold clusters on the functionalized Mo₂C were calculated.It is revealed that O and F functional groups on Mo₂C weaken the interaction between palladium and support,resulting in a 2D to 3D transformation.The structure and coordination number of palladium/gold NPs on the functionalized Mo₂C were simulated by MD,and the results of DFT calculations were further verified.Therefore,the result of the morphological transformation was applicable for supported palladium and gold from small-scale clusters to large-scale NPs.2.Aiming to the improvement of activity and selectivity in the H₂O₂ direct synthesis,the models of Pd₁₃ cluster supported on the anatase TiO₂?101?surface were used to calculated.Based on DFT calculations,making oxygen vacancy and doping carbon in the oxygen vacancy on the TiO₂?101?surface were used to regulate the binding energy of Pd₁₃ cluster on its surface,that is,regulating the metal-support interaction.Making oxygen vacancy and doping carbon in the oxygen vacancy jointly change the adsorption energy of O₂ and other intermediates during direct H₂O₂synthesis.The Bader charge analysis and charge density difference of O₂ adsorption show that the electron gain trend of O₂ is consistent with its adsorption energy.Carbon-doped oxygen vacancy TiO₂ supported Pd is beneficial to improve the selectivity of H₂O₂.