Rapid synthesis of oxygen vacancy rich CeO2 nanorods via microwave-assisted hydrothermal for low temperature CO2 methanation

• The CeO 2 nanorods were prepared by ultra-fast synthesis using microwave-assisted hydrothermal method. • The irradiation power of microwave showed a significant influence on the kinetics of nanorod structures formation. • The Ni/CeO 2 -MW400 catalyst showed outstanding catalytic performance with excellent stability over 1,000 h durability test. • The microwave-assisted method demonstrates a promising route for ultra-fast synthesis of oxygen vacancy-rich CeO 2 nanorods. In this study, CeO 2 nanorods rich in oxygen vacancies were synthesized via a microwave-assisted hydrothermal (MW) method. Ni catalysts supported on these nanorods were subsequently synthesized and evaluated for CO 2 methanation. The Ni/CeO 2 nanorod catalyst synthesized at an optimal MW power of 400 W exhibited the highest activity, achieving 76% CO 2 conversion with 100% CH 4 selectivity at a low temperature of 225 °C, outperforming the catalysts synthesized by hydrothermal synthesis (X CO2 = 33%) and those based on the commercial CeO 2 (X CO2 = 61%). Furthermore, a 1,000-hour durability test confirmed the excellent stability of the Ni/CeO 2 nanorod MW catalyst, with negligible carbon deposition and Ni sintering. The superior performance is attributed to the high concentration of oxygen vacancies generated by rapid nanorod growth under MW conditions, which enhances metal–support interaction that suppresses Ni nanoparticle agglomeration and enhances Ni dispersion. The MW method enables the formation of CeO 2 nanorods within 30 min, significantly shorter than the 24 h required for conventional hydrothermal synthesis. This work highlights microwave-assisted hydrothermal synthesis as an energy-efficient strategy for producing oxygen-vacancy-rich CeO 2 nanorods for CO 2 valorization.