Separating Catalytic Activity at Edges and Terraces on Platinum: Hydrogen Dissociation
Separating Catalytic Activity at Edges and Terraces on Platinum: Hydrogen Dissociation
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DOI：
10.1021/jp401355c
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发表时间：
2013-05-09
影响因子：
3.7
通讯作者：
Juurlink, L. B. F.
中科院分区：
文献类型：
--
作者：
Groot, I. M. N.;Kleyn, A. W.;Juurlink, L. B. F.
多相催化在很大程度上依赖于金属纳米颗粒的反应性。这些粒子的表面由原子平滑的梯田和边缘组成。由于边缘和阶地原子的局部环境不同，其催化能力也不同。这严重影响了对多相催化反应动力学的准确预测。在这项研究中，我们使用一系列[n(111)X(100)]阶梯铂单晶表面上H-2解离的反应动力学来解决如何分别分离和量化边缘和平台上原子的反应性。一个简单的反应性模型，只需要n=3的输入，就可以准确地预测入射分子在整个感兴趣的能量范围内(100)阶跃和(111)阶梯的任何组合的反应性。我们的结果支持了理论动力学研究中的假设，即最小晶胞准确地模拟了催化表面的基本特征，并讨论了这一假设的局限性。最后，根据我们的模型，我们首次量化了气体-表面碰撞中直接解离过程的绝对反应截面。
Heterogeneous catalysis relies to a large extent on the reactivity of metal nanoparticles. The surface of these particles consists of atomically smooth terraces and edges. As local environments of atoms in edges and terraces are different, their catalytic ability varies. This severely complicates accurate predictions of reaction kinetics in heterogeneous catalysis. In this study, we use the reaction dynamics of H-2 dissociation on a series of [n(111) X (100)] stepped platinum single-crystal surfaces to resolve how reactivity for atoms in edges and terraces can be separated and quantified individually. A simple reactivity model that only requires input from n = 3 accurately predicts reactivity for any combination of a (100) step with a (111) terrace over the entire energy range of interest for incident molecules. Our results support the assumption in theoretical kinetics studies that the smallest unit cell accurately models the essential features of the catalytic surface, and we discuss limitations to this assumption. Finally, from our model, we quantify for the first time the absolute reaction cross section for a direct dissociative process in a gas-surface collision.