Tailoring Dynamic Cu Redox Responsiveness via Pr-Modified Ceria for Enhanced Reverse Water–Gas Shift

Abstract The reverse water–gas shift (RWGS) reaction is a key technology for converting CO2 into CO as a versatile intermediate for chemical production. Among various catalysts, Cu/CeO2 has attracted considerable attention owing to its high CO selectivity, yet its activity is affected by the oxidation and reduction behavior of Cu under reaction conditions. Although rare-earth modification has been widely employed to improve the redox properties of ceria, the relationship between support modification and the dynamic Cu redox behavior during RWGS remains poorly understood. Herein, we demonstrate that Pr modification effectively tailors the Cu redox response of Cu/CeO2, leading to enhanced RWGS performance. Systematic comparison of lanthanide modified ceria supports revealed that Pr-modified CeO2 exhibited the highest catalytic activity while maintaining approximately 99% CO selectivity. Comprehensive structural characterization combined with in situ diffuse reflectance infrared Fourier transform spectroscopy, X-ray diffraction, and X-ray absorption fine structure spectroscopy showed no major difference in the surface species detected after Pr modification. Instead, the Pr-modified Cu/CeO2 catalyst exhibited a faster oxidation response under CO2 together with reversible reduction under an H2 atmosphere. The enhanced Cu redox dynamics are associated with the modified redox characteristics of the Pr-modified CeO2 support. These results identify dynamic Cu redox responsiveness as an important characteristic associated with the enhanced RWGS activity of the Pr-modified Cu/CeO2 catalyst and provide a practical strategy for engineering reducible oxide-supported Cu catalysts for efficient CO2 conversion.