Datensatz

Zusammenfassung

Nanoscopic gold particles have gained very high interest because of their promising catalytic activity for various chemicals reactions. Among these reactions, low-temperature CO oxidation is the most extensively studied one due to its practical relevance in environmental applications and the fundamental problems associated with its very high activity at low temperatures. Gold nanoparticles supported on manganese oxide belong to the most active gold catalysts for CO oxidation. Among a variety of manganese oxides, Mn₂O₃ is considered to be the most favorable support for gold nanoparticles with respect to catalytic activity. Gold on MnO₂ has been shown to be significantly less active than gold on Mn₂O₃ in previous work. In contrast to these previous studies, in a comprehensive study of gold nanoparticles on different manganese oxides, we developed a gold catalyst on MnO₂ nanostructures with extremely high activity. Nanosized gold particles (2–3 nm) were supported on α-MnO₂ nanowires and mesoporous β-MnO₂ nanowire arrays. The materials were extremely active at very low temperature (−80 °C) and also highly stable at 25 °C (70 h) under normal conditions for CO oxidation. The specific reaction rate of 2.8 mol_CO·h^–1·g_Au^–1 at a temperature as low as −85 °C is almost 30 times higher than that of the most active Au/Mn₂O₃ catalyst.