Alkaline mediated sono-synthesis of surface oxygen-vacancies-rich cerium oxide for efficient photocatalytic CO₂ reduction to methanol

Photocatalytic CO₂ reduction into desirable hydrocarbon products is one of the significant steps towards a sustainable ecosystem. Intriguingly, surface oxygen vacancies on pristine nanostructures enhance the effectiveness and selectivity of photocatalytic CO₂ reduction. It is proposed here that cerium oxide nanostructure can be synthesized under ultrasound irradiation in an alkaline medium for rich surface defects. The acoustic bombardment of the ceria particles has resulted in turbulence generation and substantial impact during ultrasonic treatments, which energized the synthesis reaction for surface oxygen vacancies generation. Consequently, the ultrasonic treatment boosts the photocatalytic hydrogenation performance with excellent selectivity of methanol over CO. The final products had outstanding stability, and the smaller particle size increased the photocatalyst surface area. While the generated nanostructure was incredibly stable and reusable, the greater separation efficiency of the charge carriers due to surface imperfections is examined by the time-resolved photoluminescence spectra.