First‐Principles Study of the Effects of La2+/3+ Doping and Oxygen Vacancies on TiO2 Magnetism, Carrier Lifetime, Activity, and Absorption Spectra

The effects of photocatalytic performance and magnetism between La doping and oxygen vacancy on rutile and anatase TiO2 systems are rarely compared. Oxygen vacancies in rutile and anatase TiO2 are also experimentally challenging to control accurately. Herein, the first‐principles generalized gradient approximation (GGA + U) method is used to investigate the effects of La2+/La3+doping and oxygen vacancy on TiO2 magnetism and photocatalytic performance. Results of magnetic calculation show that La2+ doping and oxygen vacancies are magnetic to TiO2, whether rutile or anatase, and that the bound magnetic polaron is the source of ferromagnetism in the anatase Ti15La2+O31 system. The anatase Ti30La22+O62 system can achieve room‐temperature ferromagnetism at Curie temperature. The calculation results of photocatalytic performance show that the anatase‐type Ti15La3+O31 system has minimum formation energy, the highest stability, maximum electric dipole moment, the strongest carrier activity, the strongest polarization ability, the slowest electron–hole recombination, the longest lifetime, and remarkable absorption spectrum redshift among the tested systems.