配体保护下的Au_8团簇吸附和活化O_2的第一性原理研究

First-principles Study of O_2 Adsorption and Activation on Ligand-protected Au_8 Clusters

采用密度泛函理论的TPSS泛函,研究在配体聚乙烯吡咯烷酮(poly(N-vinyl-2-pyrrolidone),PRD)保护下O2吸附在Au8团簇上的稳定构型的结构和电子性质。PRD通过物理吸附作用在Au8团簇上,PRD中的O与Au8形成较弱的Au-O键。相对于Au8团簇,Au8∶PRD n团簇的活性略有提高并与O2产生共吸附效应。分析表明:在共吸附中,PRD通过Au8将部分电子转移给了O2,进入了O2的LUMO轨道,促进了Au对O2的活化作用,从而提高了Au8的催化活性。

The geometrical and electronic structures of low-lying isomers of O2 adsorbed Aus clusters protected by poly （ N-vinyl-2-pyrrolidone ） （PRD） were studied by means of density functional theory calculations with TPSS functional. PRD adsorbs onto Au8 clusters via physisorption during which weak Au-O interaction is built. Compared to the bare Au8 cluster, Au8 ：PRDn has higher activity towards O2. A co-adsorption effect was noted for PRD and O2 on Aus/ Density of States （DOS） shows electrons transfer from PRD to the LUMO of O2, which promotes the activation of O2. Our calculations reveal that a small amount of charge flows from PRD to Au8 and then to the LUMO of O2 , which activates O2 and enhances its catalytic ability.