Photocatalytic and antibacterial properties of NaTaO3 nanofilms doping with Mg2+, Ca2+ and Sr2+

In this research, we prepared pure and alkaline earth metal elements (Mg2+, Ca2+ and Sr2+) doped NaTaO3 nanofilms by a simple hydrothermal method. Compared with traditional powder photocatalysts, they possess better stability and recycling performance, which makes them more practical in wastewater treatment. The as-prepared NaTaO3 crystals show nanoscale grain size that increases its redox ability owing to the small size effect and surface effect. After further introduction of Mg2+, Ca2+ and Sr2+, the band gaps were reduced to 2.83, 3.01 and 2.96 eV, respectively. Meanwhile, elemental doping induces a phase transition in the crystal structure of NaTaO3, creating an additional energy level that improves its responsiveness to visible light. According to the results, Mg-NaTaO3 catalyst possessed a higher photodegradation efficiency of 80.1 % for methylene blue solution under visible light irradiation. Furthermore, the photocatalytic bactericidal performance of different samples was investigated with Gram-positive and negative bacteria. In particular, the ROS (⋅O2–, ⋅OH, 1O2) induced by Mg-NaTaO3 could effectively destroy cell membranes, and the inhibition effect on E. coli and S. aureus reached 99.99 % within 50 min. Lastly, the results of cyclic photocatalytic experiments showed that Mg-NaTaO3 still had a high photodegradation capacity (75.2 %) and sterilization performance (98.8 %) after three cycles.