Uniform and fully exposed Rh clusters on defect-rich CeO2 enable efficient catalytic N2O decomposition

Abstract

Precise construction of single and uniform active species in supported noble metal catalysts, for clarifying structure-activity relationships and optimizing catalytic activity, is essential but highly challenging. Here we have developed a defects-assisted adsorption combined with hydrogen-induced aggregation method for controllably fabricating uniform Rh species from single atoms to nanoclusters (1.1 nm) and ultrafine nanoparticles (2.1 nm) on defect-rich CeO₂. For catalytic N₂O decomposition, Rh nanocluster catalysts with nearly 100 % Rh exposure present superior activity, with a turnover frequency (137.4 h⁻¹ at 250 °C) 4.6 times higher than Rh nanoparticles catalysts and 148.8 times higher than Rh single atoms catalysts. Mechanism studies indicate different Rh species on the defect-rich CeO₂ have various responses to O₂, mainly due to electronic effect. Rh clusters act as the optimal active species owing to the presence of adjacent Rh atoms and positively charged Rh species, facilitating the transformation of intermediates and desorption of products, respectively. Besides, defects from CeO₂ nanorods play crucial roles in the controlled catalyst synthesis process and the enhancement of catalytic activity. This work highlights that precisely constructing metal active sites with single-cluster species and appropriate electronic properties can achieve optimal catalytic performance in some structure-sensitive reactions.