Localization Of Pt Catalysts With Different Configurations And Their Adsorption Processes Of CO And O₂:A First-Principle Investigation

The current air pollution in China is obviously compound and regional.Ozone,inhalable particulate matter and fine particulate matter have been widely accepted by the general public as indicators to measure the degree of air pollution.VOCs are a kind of important precursors of ozone and fine particulate matter,and their control effect significantly affects the overall degree of air pollution.At present,the most economical and effective technology for the treatment of volatile organic compounds is catalytic combustion,but the bottleneck lies in the controllable preparation of the catalyst and the understanding of the intrinsic properties of the catalyst.These two points must be overcome to effectively improve the catalyst performance.In this study,theoretical calculation methods were used to study the structure,electronic properties and CO/O₂ adsorption and activation performance of Pt catalysts from three perspectives of crystal planes,clusters and alloys.The results can guide the experimental synthesis.First,the structure of Pt?100?,?110?,?111?crystal planes is optimized.Then a series of properties such as its geometric structure,relaxation mode,generation energy,work function,density of state and so on are studied.It is found that the crystal planes with the lowest generation energy and the easiest to donate electrons are?111?and?110?crystal planes,respectively.The adsorption and activation process of CO and O₂ was calculated on the?111?crystal plane,and the adsorption configuration and energy changes on different active sites of the crystal plane were investigated.It is found that the overall adsorption law of CO and O₂on the Slab model is the same,that is,it contacts as much Pt as possible to form bonds.Then the pure Pt clusters were investigated.First,the structure search and optimization of Ptn?n=2?9?clusters are carried out,and the energy and bond length under the stable and metastable structure are investigated,and the preliminary rules of the stability of the cluster system are obtained.In order to combine the experimental research of the research group,the metal atoms Ag,Ir,Cu,Co,Ni were selected to dope the Pt clusters.The structure optimization and electronic local density analysis of the alloy clusters show that the introduction of transition metals has little effect on the electronic polarization properties of the Pt clusters;while the noble metals Ag and Ir significantly increase the clusters'electronic localization to the greatest extent The degree of localization of electrons near Ag is lower than that of Pt,while Ir is the opposite,indicating that the electronic properties significantly affect the way Ag and Ir are dispersed in the Pt cluster.The former tends to be dispersed and the latter tends to concentrate.The calculation of the adsorption of CO and O₂ by the alloy clusters found that the introduction of heteroatoms significantly changed the adsorption performance of the clusters.From the energy point of view,all metal atoms except Ir have no or slight negative impact on the CO adsorption properties of the system.On the contrary,all alloys exhibit a stronger O₂ affinity.Considering the types of adsorption sites,when O₂adsorption occurs on pure Pt and clusters introduced with Cu and Co,the molecules tend to be adsorbed on the single-atom active sites?top positions?;while those with the introduction of Ni,Ag and Ir The adsorption capacity of the active sites?bridge sites?composed of diatomic atoms in the alloy clusters is significantly improved,and the adsorption energy is more advantageous than the top sites.