CeO₂ Nanostructures Enriched with Oxygen Vacancies for Photocatalytic CO₂ Reduction

Synthesizing nanomaterials at the expense of solar energy and the associated energy generation have utmost significance as far as environmental sustainability is concerned. Here, sunlight-assisted combustion synthesis of a nanoscale metal oxide (CeO 2 ) is reported. The sunlight, as a clean renewable energy source, is used for the first time to initiate the exothermic combustion reaction and to introduce oxygen vacancies into the CeO 2 . The current synthesis setup controls the environmental problems of gas evolution, usually associated with the conventional method, and thus maintains the green pathway. Additionally, for comparison, CeO 2 nanoparticles are also synthesized using the conventional solution combustion method (CeO 2 -CSC). It is found that the CeO 2 synthesized using sunlight-assisted combustion (CeO 2 -SAC) possesses a smaller particle size, a higher concentration of oxygen vacancies, and a narrower band gap than the CeO 2 -CSC. Therefore, CeO 2 -SAC demonstrates higher photocatalytic performance in converting CO 2 to CH 3 OH (0.702 μmol h –1 g –1 ) than the CeO 2 -CSC (0.397 μmol h –1 g –1 ), thus pointing toward environmentally benign photocatalytic CO 2 reduction.