Dopant-Driven Positive Reinforcement in Ex-Solution Process: New Strategy to Develop Highly Capable and Durable Catalytic Materials.

Abstract

The ex-solution phenomenon, a central platform for growing metal nanoparticles on the surface of host oxides in real time with high durability and a fine distribution, has recently been applied to various scientific and industrial fields, such as catalysis, sensing, and renewable energy. However, the high-temperature processing required for ex-solutions (>700 °C) limits the applicable material compositions and has hindered advances in this technique. Here, an unprecedented approach is reported for low-temperature particle ex-solution on important nanoscale binary oxides. WO₃ with a nanosheet structure is selected as the parent oxide, and Ir serves as the active metal species that produces the ex-solved metallic particles. Importantly, Ir doping facilitates a phase transition in the WO₃ bulk lattice, which further promotes Ir ex-solution at the oxide surface and eventually enables the formation of Ir particles (<3 nm) at temperatures as low as 300 °C. Low-temperature ex-solution effectively inhibits the agglomeration of WO₃ sheets while maintaining well-dispersed ex-solved particles. Furthermore, the Ir-decorated WO₃ sheets show excellent durability and H₂ S selectivity when used as sensing materials, suggesting that this is a generalizable synthetic strategy for preparing highly robust heterogeneous catalysts for a variety of applications.