Ultralow-Temperature Redispersion of Platinum Nanoparticle Catalysts

Sintering is one of the major causes of catalyst deactivation, which requires redispersion to restore catalytic activity. However, conventional redispersion methods often require harsh high-temperature conditions or introduce contaminants, both of which can degrade catalyst integrity and limit their practical applicability. Here, a novel redispersion method that achieves highly dispersed Pt/CeO₂ via NO treatment at an exceptionally low temperature of 200 °C, is visualized by in situ transmission electron microscopy (TEM) and confirmed by density functional theory (DFT). Interestingly, NO, although a milder oxidant compared to O₂, promotes more effective Pt redispersion on the CeO₂(100) surface. This behavior is governed by the kinetic behaviors of the Pt species formed under different oxidative atmospheres. Under NO, two-coordinated Pt atoms are formed, each bonded to two surface oxygen atoms. These species exhibit high mobility across the surface, enabling efficient redispersion at low temperatures. In contrast, exposure to O₂ leads to the formation of four-coordinated Pt atoms bonded to four surface oxygen atoms, which significantly restricts surface diffusion and inhibits redispersion under the same temperatures. This ultralow-temperature redispersion mechanism is not limited to Pt/CeO₂, but can also be extended to other catalyst systems, offering an energy-efficient and halogen-free alternative to conventional redispersion techniques.