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采用密度泛函理论研究Au-Pd和Au-Pt纳米团簇催化解离N2O.首先根据计算得到Au19Pd和Au19Pt团簇的最优构型(杂原子均位于团簇的表面).以Au19Pd催化解离N2O为例研究催化解离的反应机理.对此主要考虑两个反应机理,分别是Eley-Rideal(ER)和Langmuir-Hinshelwood(LH).第一个机理中N2O解离的能垒是1.118 e V,并且放热0.371 e V.N2分子脱附后,表面剩余的氧原子沿着ER路径消除需要克服的能垒是1.920e V,这比反应沿着LH路径的能垒高0.251 e V.此外根据LH机理,氧原子在表面的吸附能是-3.203 e V,而氧原子在表面转移所需的能垒是0.113 e V,这表明氧原子十分容易在团簇表面转移,从而促进氧气分子的生成.因此,LH为最优反应路径.为了比较Au19Pd和Au19Pt对N2O解离的活性,根据最优的反应路径来研究Au19Pt催化解离N2O,得到作为铂族元素的铂和钯对N2O的解离有催化活性,尤其是钯.同时,将团簇与文献中的Au-Pd合金相比较,得到这两种团簇对N2O解离有较高的活性,尤其是Au19Pd团簇.再者,O2的脱附不再是影响反应的主要原因,这可以进一步提高团簇解离N2O的活性.
Density functional theory (DFT) studies of Au-Pd and Au-Pt nanoclusters catalyze the dissociation of N2O. The optimal configurations of Au19Pd and Au19Pt clusters are obtained firstly (the heteroatoms are all located on the surface of clusters) Two reaction mechanisms, Eley-Rideal (ER) and Langmuir-Hinshelwood (LH), were investigated for the first time to study the reaction mechanism of catalytic dissociation from N2O. The first barrier to N2O dissociation was 1.118 eV and an exotherm of 0.371 e V. After desorption of N2 molecules, the residual energy of oxygen atoms on the surface is eliminated along the ER path. The energy barrier to be overcome is 1.920 eV, which is 0.251 eV higher than the energy barrier of the reaction along the LH path In addition, according to the LH mechanism, the adsorption energy of oxygen atoms on the surface is -3.203 eV, and the energy barrier required for the oxygen atoms to migrate on the surface is 0.113 eV, indicating that oxygen atoms are very easy to transfer on the surface of the clusters to promote oxygen Therefore, LH is the optimal reaction path.In order to compare the dissociation activity of Au19Pd and Au19Pt against N2O, Au19Pt was studied for its catalytic dissociation of N2O according to the optimal reaction path, and the effect of platinum and palladium as platinum group elements on the N2O Of the catalytic dissociation activity, especially palladium. At the same time, the cluster and the literature in the Au-Pd alloy In comparison, the two clusters have higher activity for the dissociation of N2O, especially the Au19Pd clusters.In addition, the desorption of O2 is no longer the main reason for the reaction, which can further improve the dissociation of N2O Activity.