Orientation Selection during Heterogeneous Nucleation: Implications for Heterogeneous Catalysis

Hybrids based on supported nanoparticles are used for many applications such as catalysis and sensing. It is well-known that the size and shape of the particles and their interaction with the substrate play a key role in controlling the properties of the hybrid. Here, we show that in addition to these commonly considered effects, the orientation of the particle on the substrate could play a critical role that could dominate over the other effects. For the same nominal size of the particle, changes in its orientation on the substrate lead to dramatic changes in the accessible surface area and the electronic structure, thus profoundly affecting the properties. Using analytical calculations, we show that the orientation of the crystal, heterogeneously nucleating on a substrate, is determined by the barrier for nucleation and experimentally demonstrate that it is possible to tune this orientation by tuning the interfacial energy between the nucleus and substrate. Our study provides some fundamentally new insights into the process of heterogeneous nucleation that can be exploited for practical applications.