Theoretical Study Of The Kinetic Behavior And Physicochemical Properties Of Nanoclusters Based On The Atomic Level

Catalysis play an important role in social development due to the issue of energy and environment.Catalysis can transform raw materials into valuable products in an efficient and green way.Therefore,it is widely used in various fields such as chemistry,biology,energy and medicine.Finding and developing high-performance catalysts with excellent stability is our goal to persist.In heterogeneous catalysis,supported nanomaterials with smaller size exhibit excellent catalytic performance in the production of petrochemical products and the preparation of fine chemicals due to their more surface-active sites.The basics of realizing high catalytic performance is to maintain the stability of nanoparticles.Unfortunately,metal nanoparticles tend to sinter and furtherly lead to deactivation of the catalyst due to the harsh reaction conditions.In order to obtain the supported metal nanoparticles with high stability and activity,it is vital to investigate the sintering behavior theoretically.With the development of science and technology,the dispersed metal single-atom catalysts have attracted extensive attention as a novel type of heterogeneous catalyst.Compared with metal-supported nanoparticles,single-atom catalysts(SACs)are widely used in a series of redox reactions because of their unique electronic structure and the maximize atomic efficiency.Maintaining their dispersed state determines the duration and the cycle frequency of catalytic performance in practical applications.A common strategy is the modification of supports.However,theoretical reports on the effect of modified substrates on SACs are still scarce.Based on the above problems,a multi-scale model combining density functional theory and all-atom kinetic Monte Carlo method were used to investigate the stability and activity of supported metal nanocatalysts.In this paper,we provided the relevant properties of the studied system through first-principles calculations,then developed the kinetic Monte Carlo model to describe the metal-metal interaction and metal-support interaction.Firstly,we adopted the model to investigate the sintering of TiO2 supported Au nanoparticles and carried out the allatom simulation through Ostwald ripening(OR)mechanism at millisecond timescales.We propose a new kinetic model to describe the rate-determining of OR in which OR is a stagewise process controlled by diffusion and interface based on the simulation results.Au dimers,rather than monomers as generally assumed,were exchanged among different nanoparticles.This work paves the way for real-time monitoring sintering process of catalyst at atomic scale.Secondly,the model was used to investigate the stability of Au atoms dispersed on the modified TiO2 surface.Decoration of substrate(such as defect and doping)could maintain the stability of the dispersed atoms by enhancing the interaction between the support and the metal atom.In the defectmodified substrate,different atom-to-defect ratio(ADR)affected the loading of dispersed atoms.Au atoms are completely dispersed when ADR is low,while they converge to integrate larger nanoparticles when ADR is high.Interestingly,the Au remained the dispersed state even if the amount of Au atoms is almost as twice as the number of oxygen vacancies.We thus provide a range of ADR for the rational design of stable Au dispersed atoms on the reduced TiO2(101)surface.Introducing oxygen vacancies(VO)on metal oxide surfaces is a common strategy to form stable SACs.However,the stability of single-atoms(SAs)anchored on VO sites under real reaction is lacking of studies.Herein,we combine the first-principles calculations and the artificial intelligence approach to high-throughput screen the stability and activity of 3d,4d,and 5d transition metals on 8 defective metal oxide surfaces during CO2 reduction reaction(CO2RR).By evaluating the anchor energies of the 232 catalytic systems,only 28 SACs remain stable with the adsorption of intermediates of CO2RR in 100 kinds of VO anchored systems in vacuum.Subgroup discovery analysis was used to explore the physical properties that affect their stability.By further comparison of the selectivity and activity,Os/Vo-ZrO2(111)is identified as the most promising candidate for the conversion of CO2 reduction CO in eletrocatalysis.Ru/Vo-ZrO2(111)is excellent catalytic performance in reverse water gas shift reaction.In addition,the reaction-driven dynamic carburizing process on Pd1-FeOx single-atom catalyst was studied in cooperation with experiments which reveals dynamic surface reconstruction behavior on single-atom site.To sum up,we studied the stability and activity of supported nanomaterials through multi-scale models to reveal the migration behavior of atomic nanomaterials and further propose the range of ADR for stable nanomaterials.In addition,combining first-principles calculations and artificial intelligence local analysis method,a high throughput screening strategy with high performance SACs in reaction was proposed.These results provide theoretical guidance for the rational design of sinter-resistance and high performance supported nanocatalysts.