Rodríguez-Kessler P L, Rodríguez-Domínguez A R
Instituto Potosino de Investigación Científica y Tecnológica, San Luis Potosí 78216, Mexico.
Instituto de Física, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78000, Mexico.
J Chem Phys. 2015 Nov 14;143(18):184312. doi: 10.1063/1.4935566.
Size and structure effects on the oxygen reduction reaction on PtN clusters with N = 12-13 atoms have been investigated using periodic density functional theory calculations with the generalized gradient approximation. To describe the catalytic activity, we calculated the O and OH adsorption energies on the cluster surface. The oxygen binding on the 3-fold hollow sites on stable Pt12-13 cluster models resulted more favorable for the reaction with O, compared with the Pt13(Ih) and Pt55(Ih) icosahedral particles, in which O binds strongly. However, the rate-limiting step resulted in the removal of the OH species due to strong adsorptions on the vertex sites, reducing the utility of the catalyst surface. On the other hand, the active sites of Pt12-13 clusters have been localized on the edge sites. In particular, the OH adsorption on a bilayer Pt12 cluster is the closest to the optimal target; with 0.0-0.2 eV weaker than the Pt(111) surface. However, more progress is necessary to activate the vertex sites of the clusters. The d-band center of PtN clusters shows that the structural dependence plays a decisive factor in the cluster reactivity.
利用广义梯度近似的周期性密度泛函理论计算，研究了原子数N = 12 - 13的PtN团簇上氧还原反应的尺寸和结构效应。为了描述催化活性，我们计算了团簇表面上O和OH的吸附能。与O强烈结合的Pt13（Ih）和Pt55（Ih）二十面体颗粒相比，稳定的Pt12 - 13团簇模型上3重中空位点上的氧结合对与O的反应更有利。然而，由于在顶点位点上的强吸附，限速步骤导致OH物种的去除，降低了催化剂表面的效用。另一方面，Pt12 - 13团簇的活性位点位于边缘位点。特别是，双层Pt12团簇上的OH吸附最接近最佳目标；比Pt(111)表面弱0.0 - 0.2 eV。然而，要激活团簇的顶点位点还需要更多进展。PtN团簇的d带中心表明，结构依赖性在团簇反应性中起决定性作用。
