Mechanism Study On The Adsorption And Reduction Of CO₂ Over Platinum Clusters Doped Graphene

Being accompanied by the high-speed growth of modern industry,plenty of fossil fuel combustion created that carbon dioxide discharges into the atmospheric environment by human is mounting up.For the sake of reducing CO₂ emissions with advantage,it is essential to study CO₂ treatment technology.The adsorption and resource utilization of CO₂ has been widely concerned,and the most common conversion reaction is catalytic reduction of CO₂,which can not only reduce the content of greenhouse gases,but also obtain products with high industrial added value,which can get significant profit in both environment and economy.At present,the biggest challenge of carbon dioxide catalytic reduction is the chemical st ability of CO₂.The activity and efficiency of common catalysts are very low.Therefore,the research and devise of high-performance catalysts has turned into a vital research direction in the current CO₂ treatment technology.From this work,in view of density functional theory,the Pt_n/GN（n=1,2,3,4）series catalysts supported on graphene substrates with single or double vacancy doping different numbers of nitrogen atoms were simulated.A total of 44 catalyst configurations were calculated.The binding energy calculation showed that all the 44Pt_n/GN catalysts had good stability.And the adsorption of CO₂ on these catalysts was further studied.The results show that the adsorption configuration is that carbon and oxygen atoms interact with Pt atoms at the same time,and CO₂ has a certain degree of activation.Through studying the Bader charge transfer,electron density difference and projected density of states of these 44 catalysts for CO₂ adsorption,we found that electrons mainly transferred from Pt_n clusters to CO₂ molecules in the process of CO₂adsorption.The d orbital of Pt superposes upon the p orbital of CO₂ molecule,which indicates that there is covalent interaction between them.Using the selected Pt₄/SV catalyst,combined with two different reducing agents of H₂ and CH₄,the CO₂ reduction reaction was calculated.In the reaction of CO₂reduction with H₂,the reaction paths under different mechanisms（E-R,L-H,TER）were studied to explore the dominant reaction path of CO₂ reduction,and the thermodynamic as well as kinetic analysis were in progress.Those outcomes show that the reaction has greater odds to develop under TER mechanism.In the reaction of CO₂reduction with CH₄,the reaction routes of methane decomposition,CO₂ activation and CH/C oxidation were systematically discussed,and the thermodynamics as well as kinetics of CH/C oxidation were developed similarly.In the procedure of methane decomposition,the stage of CH decomposition into C and H is the most critical procedure.The preferential reaction route of CO₂ activation is CO₂*→CO*+O*.In the process of CH/C oxidation,CH*+O*→CHO*+*→CO*+H*and C*+O*→CO*+*are more likely to occur.