Internal magnetic-field-enhanced photogenerated charge separation in ferromagnetic TiO2 surface heterojunctions.

• Ferromagnetic TiO 2 was prepared by regulation of crystal structure and defects. • The saturation magnetisation (M S) was measured to be as high as 0.0014 emu/g. • Experiments and simulation are used to investigate the ferromagnetism mechanism. • The photoelectrochemical performance was improved by ferromagnetic field in the bulk. • The proposed approach can be used to other oxide systems. The use of the internal magnetic field of ferromagnets can effectively promote charge separation and transfer (CST) in photoelectrochemical energy conversion. However, photoelectrochemical materials with a ferromagnetic field are scarce, and the internal magnetic field is negligible in nonferromagnetic materials. To address this issue, we propose a rational method for preparing ferromagnetic TiO 2 powder using controllable oxygen vacancies in anatase TiO 2 with co-exposed {001} and {101} facets. Accordingly, an excellent saturation magnetisation of 0.0014 emu/g in TiO 2 is achieved owing to an asymmetric and uneven charge distribution. Compared with that of nonferromagnetic TiO 2 , the efficiency of photocatalytic hydrogen generation of ferromagnetic TiO 2 is improved by 0.64 times. The enhancement of photocatalytic hydrogen generation is due to the different forces exerted on the electrons and holes in the magnetic field, which significantly improve the photogenerated CST efficiency of ferromagnetic TiO 2. This result highlights the significant role of the synergistic regulation of the crystal structure and defects in regulating the ferromagnetic characteristics of materials. The findings of this study provide guidance for leveraging point defects to promote CST for high-efficiency solar-energy conversion systems. Ferromagnetic TiO 2 with co-exposed {001} and {101} facets was prepared via controllable oxygen vacancies. The different forces exerted on the electrons and holes in the magnetic field significantly improve the photogenerated CST efficiency of ferromagnetic TiO 2 [Display omitted] [ABSTRACT FROM AUTHOR]