Shape-shifting nanoparticles on a perovskite oxide for highly stable and active heterogeneous catalysis

Abstract

Controlling the geometric shape of nano-catalysts plays a key role in maximizing unique properties of the materials. Although shape control of nanoparticles is well known by various preparation methods, still there is no clear case for exsolution. Here we show that the shape of embedded Ni nanoparticles can be changed on exsolution process, by controlling reduction temperature and time. To elucidate and generalize the shape-shifting, we develop a model which describes the equilibrium shape of nanoparticles on support thermodynamically. Our results suggest that there is a thermodynamic driving force for the exsolved nanoparticle to be stabilized into faceted shape with low surface/interface energy, during the particle growth. Through catalytic activity testing, the improved durability of shape-shifted Ni catalysts is confirmed on dry-reforming condition over 390 h, resulting from enhanced interface stability and cocking resistance. This provides theoretical and experimental framework for the shape control of exsolved particle on oxide support, but also for the design of unique catalyst with high stability and reactivity.