Study On The Cluster Model Of Single-Atom Copper Group Catalysts

With the deteriorating environment of modern society,how to realize green chemistry has become a key concern of the current chemical industry.The oxidation reaction,as a kind of basic reactions in chemistry,the realization of the green oxidation reaction has become the hot topic of current research.Choosing an environmentally friendly oxidant is an effective way.Because oxygen can be obtained from the air at a relatively low cost,and the product after the reaction has little environmental pollution,it has attracted much attention regarded as an ideal oxidant.In addition,in the oxidation reaction,a catalyst with high activity and high selectivity can significantly improve the reaction efficiency,and a suitable catalyst can also reduce the environmental pollution products after the reaction.Therefore,combining a suitable catalyst and the green oxidant oxygen is an effective solution to achieve green chemistry.Unlike the complexity of the actual reaction and many interferences in the research,the structure and reaction of cluster are relatively simple.Therefore,cluster is used as an ideal model to explain the reaction mechanism from the molecular scale.The main research contents of this paper are as follows:MSi_nO_2n+1+1-（M=Cu,Ag,Au;n=1,2,3）was used as a cluster model to study the activation of oxygen molecules on single-atom catalysts.We did global optimization of MSi_nO_2n+1+1-clusters to find the most stable structure based on density functional theory.The oxygen is adsorbed on the most stable configuration of MSi_nO_2n+1+1-,forming the adsorption complexes MSi_nO_2n+1+1--O2,and oxygen prefer to be adsorbed on metal atoms.By comparing the bond length,the vibrational frequency,FBO,NPA charge on the adsorbed O2 moiety,and the dissociation barrier of oxygen,it is found that smaller clusters always have higher reactivity toward O2,and Cu-containing clusters can absorb and activate oxygen in a higher degree than Au/Ag-containing clusters.The analysis of the HOMO orbital composition of MSi_nO_2n+1+1-cluster deeply explains the high reactivity of the Cu-containing clusters.Because the reaction process is relatively simple,the oxidation reaction of CO is regarded as a model reaction for exploring the mechanism of catalytic oxidation.In this paper,reaction processes of CO oxidation with the adsorption complexes CuSinO2n+1--O2 with CO2 desorpted were calculated.The results show that as the size of CuSinO2n+1-clusters increasing,the reactivity of the clusters decreasing.