白金ナノ粒子触媒の超低温再分散

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.