Boosting low-concentration toluene oxidation by decorating ultrasmall Pt nanoparticles on La0.8Sr0.2MnO3-δ with hydrogen plasma treatment

Abstract

Perovskite is one of the most promising materials for catalytic oxidation of volatile organic compounds (VOCs) because of its special tunable structure and properties as well as high stability. However, it commonly suffers from relatively low catalytic activity due to the low specific surface area and limited numbers of active sites caused by high synthesis temperature required. To improve the reactivity of the perovskite catalyst, a promising strategy is to construct highly dispersed noble metal sites on surfaces perovskite. However, generating highly active metallic sites while exhibiting good thermal stability remains a formidable challenge. Here, it’s demonstrated that the construction of highly efficient and robust platinum (Pt) sites on La_0.8Sr_0.2MnO_3-δ (Pt/LSMO) for toluene oxidation resulted in an almost three-fold increase in toluene conversion with a good stability. The key to the construction of these Pt sites is treating the oxidized Pt species on LSMO with hydrogen (H₂) plasma at low temperatures, which leads to the formation of high metallic Pt (Pt⁰), ultrasmall Pt nanoparticles (∼1.3 nm), and high concentration of oxygen vacancy (O_v). These features facilitate the generation of a large number of highly active and stable Pt⁰-Mn³⁺-O_v sites on Pt/LSMO, which contribute to the activation of toluene and oxygen species and, therefore, the catalytic reaction. This investigation demonstrates a promising approach of using the cold plasma technique to design and construct high-performing noble-based perovskite catalysts for toluene oxidation.