A Subnanometric Ruthenium Cluster Catalyst Boosts Water-Induced Autoexhaust Soot Oxidation

Tailoring the surface atomic structure of materials is an efficient strategy to improve catalytic performances during deep oxidation reactions, such as autoexhaust soot oxidation. Herein, a robust catalyst of subnanometric ruthenium (Ru) clusters supported on a cubic CeO₂ nanocrystal with exposed {100} facets (Ru/CeO₂-C) is designed to realize high performance for soot oxidation. The heterostructure interface between Ru clusters and CeO₂-{100} facets induces a strong interaction that facilitates the dissociation of H₂O. The Ru/CeO₂-C catalyst exhibits impressive water-dependent catalytic activity and thermal stability during soot oxidation. In the presence of water vapor as a usual catalytic inhibitory poison, its value of T₅₀ (temperature of half of soot oxidation) and TOF (turnover frequency) is 312 °C and 1.21 h^-1, respectively, and the rate of soot oxidation is 1.38-fold of the absence of water. Comprehensive experimental and theoretical calculations analyses substantiate that the interfacial Ru^&+-O_v-Ce³⁺ bond chain structure significantly promotes H₂O dissociation and O₂ activation, resulting in the generation of highly reactive oxygen species (OH*/OOH*). The generated OH*/NO₂ species can attack the edge carbon atoms of soot, leading to the formation of surface oxygen complexes that act as crucial reaction intermediates. The water vapor acts as an "initiator" and can enhance the decomposition of the surface oxygen complexes through hydrolysis and decarboxylation to promote soot oxidation. This finding has significant implications for filling the knowledge gaps in the water-promoted catalytic oxidation of the autoexhaust carbon particle and designing an effective water-resistant catalyst for autoexhaust purification.