Enhanced Catalytic Oxidation Reactivity over Atomically Dispersed Pt/CeO₂ Catalysts by CO Activation

Abstract

The elevation of the low-temperature oxidation activity for Pt/CeO₂ catalysts is challenging to meet the increasingly stringent requirements for effectively eliminating carbon monoxide (CO) from automobile exhaust. Although reducing activation is a facile strategy for boosting reactivity, past research has mainly concentrated on applying H₂ as the reductant, ignoring the reduction capabilities of CO itself, a prevalent component of automobile exhaust. Herein, atomically dispersed Pt/CeO₂ was fabricated and activated by CO, which could lower the 90% conversion temperature (T₉₀) by 256 °C and achieve a 20-fold higher CO consumption rate at 200 °C. The activated Pt/CeO₂ catalysts showed exceptional catalytic oxidation activity and robust hydrothermal stability under the simulated working conditions for gasoline or diesel exhausts. Characterization results illustrated that the CO activation triggered the formation of a large portion of Pt⁰ terrace sites, acting as inherent active sites for CO oxidation. Besides, CO activation weakened the Pt-O-Ce bond strength to generate a surface oxygen vacancy (V_o). It served as the oxygen reservoir to store the dissociated oxygen and convert it into active dioxygen intermediates. Conversely, H₂ activation failed to stimulate V_o, but triggered a deactivating transformation of the Pt nanocluster into inactive Pt_xO_y in the presence of oxygen. The present work offers coherent insight into the upsurging effect of CO activation on Pt/CeO₂, aiming to set up a valuable avenue in elevating the efficiency of eliminating CO, C₃H₆, and NH₃ from automobile exhaust.