Introduction. Perovskite KTaO₃ is regarded as a promising photocatalyst owing to its high stability and structural adaptability to substitution. The possibility of substituting oxygen with nitrogen or sulfur in its lattice allows the band gap to be reduced and the material response in the visible region of the spectrum to be enhanced. In this work, the oxysulfide perovskite KTaO_3-xS_x is presented, and the effect of sulfur content on its structure and photocatalytic properties under solar-light irradiation is investigated.

Materials and Methods. KTaO_3-xS_x powders were obtained in two steps: KTaO₃ was first synthesised via a solid-state reaction between K₂CO₃ and Ta₂O₅ at 800 °C for 8 h, and then KTaO₃ was treated at 600 °C in an H₂S atmosphere. The sulfur content was determined by means of EDS, and changes in the crystal structure were monitored via XRD. The photocatalytic activity of KTaO_3-xS_x particles was evaluated from the degradation of rhodamine B (RhB), and the contribution of different catalytically active species to the photocatalytic process was assessed by means of scavenger experiments.

Results. Oxysulfide perovskites KTaO_3-xS_x with sulfur contents of 1.8, 4.2 and 7.4 at.% were obtained. The samples are single-phase, and the KTaO₃ structure is preserved over the entire sulfur-doping range studied. The KTaO_2,79S_0,21 sample (4.2 at.% S) exhibits the highest photocatalytic activity under solar-light irradiation: in RhB degradation, its activity is 2.25 times higher than that of pristine KTaO₃, with superoxide anion O₂•⁻ being the main active species.

Conclusions. It is shown that sulfurization of KTaO₃ in H₂S vapor enables controlled formation of the oxysulfide perovskite KTaO_3-xS_x. Sulfur doping increases the photocatalytic activity by more than a factor of two: the composition containing 4.2 at.% S exhibits an activity of 12.5 mg·g^-1·h^-1 in RhB degradation under solar-light irradiation.

This work was supported by the Russian Science Foundation (25-19-00458).