Au atoms doped in Ti3C2Tx MXene: Benefiting recovery of oxygen vacancies towards photocatalytic aerobic oxidation

Photocatalytic aerobic oxidation by using oxygen molecules (O-2) as green and low-cost oxidants is of great attraction, where the introduction of irradiation has been proved as an efficient strategy to lower reaction temperature as well as promote catalytic performance. Moreover, the oxygen vacancies (OVs) of catalyst are highly active sites to adsorb and activate O-2 during photocatalytic aerobic oxidation. However, OVs are easily blocked by oxygen atoms from active oxygen species during the catalytic process, leading to the deactivation of catalysis. Herein, a promising catalyst toward photocatalytic aerobic oxidation was successfully developed by recovering the OVs through doping Au atoms into Ti3C2Tx MXene (Au/Ti3C2Tx). Impressively, Au/Ti3C2Tx exhibited remarkable activity under full-spectrum irradiation towards photooxidation of methyl phenyl sulfide (MPS) and methylene blue (MB), attaining a conversion of >90% at room temperature. Moreover, Au/Ti3C2Tx also manifested remarkable stability by maintaining >95% initial activity after 10 successive reaction rounds. Further mechanistic studies indicated that the OVs of Au/Ti3C2Tx served as the active centers to efficiently adsorb and activate O-2. More importantly, the doped Au atoms of Au/Ti3C2Tx were conducive to the recovery of OVs during photocatalytic process from the results of theoretical and experimental aspects. The recovered OVs of Au/Ti3C2Tx continuously and efficiently activated O-2, directly contributing to the remarkable catalytic activity and stability.

Automated summary

Photocatalytic aerobic oxidation using oxygen molecules as oxidants is attractive, but oxygen vacancies in catalysts can easily be blocked, leading to deactivation. A promising catalyst incorporating Au atoms successfully recovered oxygen vacancies and showed remarkable activity and stability for photooxidation. The recovered oxygen vacancies continuously activated oxygen molecules, contributing to the remarkable catalytic performance and stability.