Mild generation of surface oxygen vacancies on CeO(2)for improved CO(2)photoreduction activity

摘要

The vacancy defects of semiconductor photocatalysts play key roles in enhancing their photocatalytic CO(2)reduction activity. In this work, CeO(2)was chosen as a model catalyst and oxygen vacancies were introduced on its surface by a facile and mild oxalic acid treatment followed by moderate heating in N-2. Such a treatment resulted in a much increased ratio of Ce3+/Ce(4+)in CeO2, and the oxygen vacancy-enriched CeO(2)showed remarkably enhanced photocatalytic activity in CO(2)reduction, with CO being the dominant reduction product, whose yield was about 8 times that on the pristine CeO2.In situFT-IR spectra showed that the abundant oxygen vacancies substantially improved the CO(2)adsorption/activation on the surface of CeO2, which facilitated the subsequent reduction of CO2. However, the carbonates strongly adsorbed on the photocatalyst surface might be the main obstacle to maintaining the high CO(2)reduction activity and stability of CeO(2)with O vacancies.