Hydrogen Adsorption, Dissociation, and Spillover on Ru10 Clusters Supported on Anatase TiO2 and Tetragonal ZrO2 (101) Surfaces
Hydrogen Adsorption, Dissociation, and Spillover on Ru10 Clusters Supported on Anatase TiO2 and Tetragonal ZrO2 (101) Surfaces
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DOI：
10.1021/acscatal.5b01093
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发表时间：
2015-09-01
期刊：
影响因子：
12.9
通讯作者：
Pacchioni, Gianfranco
中科院分区：
文献类型：
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作者：
Chen, Hsin-Yi Tiffany;Tosoni, Sergio;Pacchioni, Gianfranco
本工作的范围是在原子水平上研究氧化物表面的金属颗粒促进氢溢出的机制。利用Hubbard修正的密度泛函理论（DFT+U）方法，研究了Ru-10纳米团簇存在下，氢分子在α-TiO_2（101）和t-ZrO_2（101）表面的吸附和解离.负载的金属颗粒的作用是必不可少的，因为它有利于H-2的自发解离，这是一个不会发生在裸露的氧化物表面上的过程。在低氢覆盖率下，H原子更倾向于停留在Ru-10颗粒上，电荷在金属簇上积累，并且氧化物的还原不发生。在羟基化的表面上，Ru纳米颗粒的存在预计会促进反向效应，即氢从氧化物反向溢出到负载的金属。只有在高的氢覆盖率，导致在金属簇上的几个H-2分子的吸附，它变得在化学上有利的氢转移从金属的氧化物表面的O位点。在两个TiO 2，和ZrO 2表面的迁移的一个H原子从Ru簇的表面是伴随着电子转移到空状态的支持与氧化物表面的还原。
The scope of this work is to study at atomistic level the mechanism of hydrogen spillover promoted by metal particles on oxide surfaces. By means of Density Functional Theory calculations with Hubbard correction (DFT+U) we have analyzed the adsorption and dissociation of molecular hydrogen on anatase titania, a-TiO2 (101), and tetragonal zirconia, t-ZrO2 (101), surfaces in the presence of a supported Ru-10 nanocluster. The role of the supported metal particle is essential as it favors the spontaneous dissociation of H-2, a process which does not occur on the bare oxide surface. At low hydrogen coverage, the H atoms prefer to stay on the Ru-10 particle, charge accumulates on the metal cluster, and reduction of the oxide does not take place. On a hydroxylated surface, the presence of a Ru nanoparticle is expected to promote the reverse effect, i.e. hydrogen reverse spillover from the oxide to the supported metal. It is only at high hydrogen coverage, resulting in the adsorption of several H-2 molecules on the metal cluster, that it becomes thermodynamically favorable to have hydrogen transfer from the metal to the O sites of the oxide surface. In both TiO2, and ZrO2 surfaces the migration of an H atom from the Ru cluster to the surface is accompanied by an electron transfer to the empty states of the support with reduction of the oxide surface.