团簇Ni_3CoP催化析氢活性研究

Catalytic Properties of Cluster Ni_3CoP in the Hydrogen Evolution Reaction

基于密度泛函理论(density functional theory,DFT),在B3LYP/lanl2dz水平下对团簇Ni3CoP的初始构型进行单、三重态下的计算得到优化构型,依据前线轨道理论(frontier molecular orbital theory,FMO)着重通过分析前线轨道图以及比较前线轨道能级差对团簇Ni3CoP催化水析出氢气时的反应机理进行理论研究,结果表明:团簇Ni3CoP通过其最高占据分子轨道(highest occupied molecular orbital,HOMO)与水分子最低未占分子轨道(lowest unoccupied molecular orbital,HUMO)间的电子流动完成氢原子的吸附,且三重态构型在与水分子作用时,其β-HOMO轨道在反应中起主导作用。三重态构型在吸附氢原子后其促进解吸过程析出氢气的催化活性显著下降,而唯一的单重态构型1(1)不仅能在与水分子反应吸附氢原子的过程中展现出较好的催化效果,其在解吸过程中更是表现出了远好于其他三重态构型的催化能力。

Based on density functional theory(DFT),the primary structures of cluster Ni3CoP were optimized in singlet and triplet under B3LYP/lanl2dz level.According to the frontier molecular orbital theory(FMO),the mechanism of the hydrogen evolution reaction catalyzed by cluster Ni3CoP was studied theoretically from aspects of the frontier molecular orbital images and the difference between the frontier molecular orbital energy levels.Results showed that cluster Ni3CoP adsorbs H atom through electrons flowing from the highest occupied molecular orbital(HOMO)of cluster Ni3CoP to the lowest unoccupied molecular orbital(LUMO)of H2O.As for configurations in triplet,β-HOMO plays a prominent role in the reaction;however,their catalytic properties can descend apparently in the desorption of H atom to generate H2.Nevertheless,structure1(1),the only configuration in singlet,can not only perform relatively good catalytic capability in adsorbing H atom from H2O but also improve the desorption process greatly compared with other configurations in triplet.