Enhanced Catalytic Oxidation Reactivity over Atomically Dispersed Pt/CeO<sub>2</sub> Catalysts by CO Activation
Zihao Li, Zhisong Liu, Guanqun Gao, Weina Zhao, Yongjun Jiang, Xuan Tang, Sheng Dai, Zan Qu, Naiqiang Yan, Lei Ma
Abstract
The elevation of the low-temperature oxidation activity for Pt/CeO 2 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 H 2 as the reductant, ignoring the reduction capabilities of CO itself, a prevalent component of automobile exhaust. Herein, atomically dispersed Pt/CeO 2 was fabricated and activated by CO, which could lower the 90% conversion temperature ( T 90 ) by 256 °C and achieve a 20-fold higher CO consumption rate at 200 °C. The activated Pt/CeO 2 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 Pt 0 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, H 2 activation failed to stimulate V o, but triggered a deactivating transformation of the Pt nanocluster into inactive Pt x O y in the presence of oxygen. The present work offers coherent insight into the upsurging effect of CO activation on Pt/CeO 2, aiming to set up a valuable avenue in elevating the efficiency of eliminating CO, C 3 H 6, and NH 3 from automobile exhaust.