Industrial catalysts are often comprised of nanoparticles supported on high-surface-area oxides, in order to maximise the catalytically active surface area and thereby utilise the active material better. These nanoparticles expose steps and corners that, due to low coordination to neighboring atoms, are more reactive and, as a consequence, are often assumed to have higher catalytic activity. We have investigated the reaction between CO and preadsorbed O on a stepped Rh(553) surface, and show that CO oxidation indeed occurs faster than on the flat Rh(111) surface at the same temperature. However, we do find that this is not a result of reactions at the step sites but rather at the terrace sites close to the steps, due to in-plane relaxation enabled by the step. This insight can provide ways to optimize the shape of the nanoparticles to further improve the activity of certain reactions.

工业催化剂通常由负载在高表面积氧化物上的纳米粒子组成，以最大化催化活性表面积，从而更好地利用活性材料。这些纳米粒子暴露出台阶和角落，由于与相邻原子的配位低，因此反应性更强，因此通常被认为具有更高的催化活性。我们研究了 CO 与阶梯式 Rh(553) 表面上预吸附的 O 之间的反应，并表明在相同温度下，CO 氧化确实比平坦的 Rh(111) 表面发生得更快。然而，我们确实发现这不是台阶部位反应的结果，而是台阶附近台阶部位的反应结果，这是由于台阶引起的平面内松弛。