Stepped metal surfaces are usually assumed to exhibit an increased catalytic activity for bond cleavage of small molecules over their flat single-crystal counterparts. We present experimental and theoretical data on the dissociative adsorption of molecular hydrogen on copper that contradicts this notion. We observe hydrogen molecules to be more reactive on the flat Cu(111) than on the stepped Cu(211) surface. We suggest that this exceptional behavior is due to a geometric effect, that is, that bond cleavage on the flat surface does not occur preferentially over a top site.

中文翻译：

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反应性对阶跃存在的反常依赖性：D ₂在Cu（211）上的解离

通常认为阶梯状金属表面在其平坦的单晶对应物上对小分子的键裂解表现出增强的催化活性。我们提供了与分子氢在铜上的解离吸附相矛盾的实验和理论数据。我们观察到氢分子在平坦的Cu（111）上比在阶梯状的Cu（211）表面上更具反应性。我们建议这种异常行为是由于几何效应引起的，也就是说，在平面上的键断裂不会优先发生在顶部部位。