An environmentally adaptive gold single-atom catalyst with variable valence states

Abstract

Single-atom catalysts revolutionize catalysis by maximizing atomic efficiency and enhancing reaction specificity, offering high activity and selectivity with minimal material usage, which is crucial for sustainable processes. However, the unique properties that distinguish single-atom catalysts from other forms, including bulk and nanoparticle catalysts, as well as the physical mechanisms behind their high activity and selectivity, remain unclear, limiting their broader application. Here, through first-principles calculations, we have identified an environmentally adaptive gold single-atom catalyst on a CeO₂(111) surface capable of adjusting its valence state in response to different environmental conditions. This adaptability enables the catalyst to simultaneously maintain high stability and activity. In a CO gas atmosphere, numerous oxygen vacancies form on the CeO₂(111) surface, where Au single atoms stably adsorb, exhibiting a negative oxidation state that deactivates the catalyst. In an O₂ atmosphere, these vacancies are filled, causing the Au single atoms to adsorb onto lattice oxygen and become oxidized to a positive oxidation state, thereby reactivating the catalyst. Under CO oxidation reaction conditions, the Au single atoms oscillate between these positive and negative oxidation states, effectively facilitating the CO oxidation process. These findings provide new insights into the unique properties and high performance of single-atom catalysts, contributing to a better understanding and utilization of these catalysts in various applications.