非晶态合金Co-Mn-B的电荷转移及其催化性质的DFT研究

Density Functional Theory Study on Electron Transfer and Catalytic Activity of Amorphous Co-Mn-B Alloy

为深入了解非晶态合金Co-Mn-B的电子及其催化性能,利用密度泛函理论(DFT)方法,在B3LYP/Lan12dz水平下,将原子簇Co2MnB2的十余种可能构型分别在二、四重态下进行全参数优化计算和频率验证,最后获得两种类型的稳定构型(三角双锥型和变形四方锥型),其中三角双锥构型均是以金属原子为两锥、一金属原子和双B原子位于三角平面。对这些稳定构型的电荷转移及其催化活性进行研究分析,结果表明:原子簇Co2MnB2稳定构型中电子主要由Mn原子向B原子转移,Mn原子的引入起到调变B原子的电子流向作用。金属Co、Mn原子在二、四重态下对HOMO、LUMO轨道的贡献大小不一样;Mn原子的饱和轨道比Co原子更富电子。原子簇Co2MnB2因空轨道易于接受反应物的电子而具有良好的催化性能;构型4(2)具有较好的催化加氢、固氮活性。

More than ten different configurations of Co2MnB2 cluster with doublet and quadruplet multiple states were calculated under the B3LYP/Lan12 dz level by using the Density Functional Theory（DFT）method.After the frequencies of each configuration were verified,two types of stable configurations were gained,including triangle dipyramid in which the metal atoms displayed on the dipyramid and deformed pentagon.At the same time,the electron transfer and catalytic activity of Co2MnB2 cluster were also studied.The results showed that in all stable configurations of Co2MnB2 cluster,the electrons were mainly transferred from the atom Mn to atom B.The addition of atom Mn modified the electronic direction of atom B.The atom Co and Mn in different multiple states gave a different contribution to the HOMO and LUMO orbits.There existed more electrons in saturated orbits of atom Mn than in atom Co.Since Co2MnB2 cluster had plenty of saturated orbits,it possessed high catalytic activity.The configuration 4^（2） possessed the highest activity in hydrogenation and nitrogen fixation reactions.