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 asprepared 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 (center dot O-2(-), center dot OH, O-1(2)) 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 MgNaTaO3 still had a high photodegradation capacity (75.2 %) and sterilization performance (98.8 %) after three cycles.