Enhanced CO2 Adsorption on CeO2/SBA-15: The Key Role of Oxygen Vacancies

Abstract

This study investigates the role of oxygen vacancies in the CO2 adsorption and desorption dynamics of SBA-15:CeO2 nanocomposites synthesized by direct (DS) and postsynthesis (PS) methods. Physicochemical analyses reveal that the DS method increases the concentration of oxygen vacancies and structural defects within the CeO2 framework, which significantly boosts CO2 adsorption capacity and strengthens the gas-surface interactions. Among the materials, S_Ce4.a demonstrates the highest adsorption capacity, reaching 29.4 mg g−1 at 25 °C and 10.7 mg g−1 at 70 °C. These results indicate a physisorption mechanism governed by both thermal conditions and oxygen vacancies. Furthermore, S_Ce4.a and S_Ce10.a. exhibit remarkable stability over 20 adsorption–desorption cycles. The findings suggest that a lower cerium oxide content provides more accessible adsorption sites, making these materials promising candidates for high-performance. Overall, this work highlights synergistic interplay between oxygen vacancies and mesoporous structures, paving the way for the rational design of advanced materials for CO2 capture technologies.