Theoretical Study Of Co Oxidation Mechanism On Pd And Ir Single Atom Catalysts

The emission of carbon monoxide?CO?affects human health,and also make catalysts and fuel cell poison.Currently,the oxidation of CO is one of the most sample and effective method to remove CO.Specially,as a probe reaction,the oxidation of CO is usually to judge the activity of a new catalyst.Thus,the studies of the CO oxidation have attracted a lot of interests on both of the theoretical simulation and experimental research.As the traditional catalysts,noble metals are the normal catalysts to oxidize CO.Given the cost and other advantages,the single metal atom catalysts are more and more popular to replace the traditional noble metal catalysts.Indeed,the 2D materials supported single metal atoms not only maximize the efficiency of metal atom use but also exhibit more superior catalytic activity than conventional metal nanoparticles in many important chemical reactions.Based on the dispersion-corrected density function theory calculations,this work investigated various reaction mechanisms of CO oxidation catalyzed by Pd-graphene and Ir-graphdiyne system.The main results are:1)CO oxidation on Pd-graphene prefers a"new"TER mechanism rather than the traditional ER?1.23 eV?and LH?0.60 eV?mechanism with the lowest rate-limiting reaction barrier of 0.29 eV.It is found that the single Pd atom embedded defect-graphene is more active to CO oxidation than the other metal?Fe?Pt?Au?Cu?Al and Mo?modified graphene according to the transition states calculations.The good catalytic activity indicates that Pd-graphene is one of the promising candidates for solving the environmentally harmful exhaust gases generated from vehicles and industrial wastes.2)A new and more efficient ER reaction pathway was designed by analyzing the adsorption and transition state structure during oxidation process on Ir-graphdiyne,in which the two CO near the adsorbed O₂ promote the activation of O₂ to generate two CO₂ at the same time,the rate-limiting reaction barrier is only 0.37 eV.It is found that the single Ir atom embedded graphdiyne is more active to CO oxidation than metal-free graphdiyne as well as other single atom?Sc,Ti?modified graphdiyne according to the transition states calculations at the room temperature.