Unveiling the gas-dependent active site evolutions on CuOx/CeO2 catalysts for CO oxidation
Fei-Xiang Tian, Yuan Gao, Liuqingqing Yang, Yulian He
Abstract
Abstract Tailoring interfacial structures in CuO x /CeO 2 catalysts via pretreatment atmosphere significantly modulates their CO oxidation performance. Catalysts were pretreated under oxidation (CuCe-Oxi), reaction (CuCe-Rex), and reduction (CuCe-Red) atmospheres. CuCe-Red exhibits superior activity, achieving 66% CO conversion at 70 °C, markedly higher than CuCe-Rex (45%) and CuCe-Oxi (33%). Crucially, the intrinsic activity (TOF) of CuCe-Red is double that of the others, directly linked to distinct interfacial site structures induced by pretreatment. In-situ spectroscopy and temperature-programmed techniques reveal that reductive pretreatment generates key active sites: low-coordinated Cu + sites and strongly interacting [Cu m+ -O x -Ce n+ ] interfacial species (including Cu 2+ -O L -Ce 4+ and asymmetric oxygen vacancy Cu + -O v -Ce 3+ configurations). The proportion of these specific sites correlates positively with TOF. The low-coordinated Cu + sites substantially enhance CO surface coverage and improve CO activation. Systematic kinetic analysis, O 2 -TPO, and CO-TPD confirm the reaction follows the Mars-van Krevelen mechanism. CO surface activation is identified as the rate-determining step (RDS). Therefore, this study demonstrates that targeted manipulation of the catalyst's interfacial microenvironment through pretreatment atmosphere controls the formation of highly active low-coordinated Cu + and specific [Cu m+ -O x -Ce n+ ] species. This structural evolution directly governs CO adsorption, activation, and ultimately, catalytic performance, providing deep insights into the structure–activity relationship for CuO x /CeO 2 oxidation catalysts. Graphical Abstract