CeO2 Nanostructures Enriched with Oxygen Vacancies for Photocatalytic CO2 Reduction

Abstract

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 (CeO2) 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 CeO2. 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, CeO2 nanoparticles are also synthesized using the conventional solution combustion method (CeO2-CSC). It is found that the CeO2 synthesized using sunlight-assisted combustion (CeO2-SAC) possesses a smaller particle size, a higher concentration of oxygen vacancies, and a narrower band gap than the CeO2-CSC. Therefore, CeO2-SAC demonstrates higher photocatalytic performance in converting CO2 to CH3OH (0.702 ?mol h-1 g-1) than the CeO2-CSC (0.397 ?mol h-1 g-1), thus pointing toward environmentally benign photocatalytic CO2 reduction.