Effect of B 2 O 3 on the Structure, Properties and Antibacterial Abilities of Sol-Gel-Derived TiO 2 /TeO 2 /B 2 O 3 Powders.

This paper studies the influence of B 2 O 3 on the structure, properties and antibacterial abilities of sol-gel-derived TiO 2 /TeO 2 /B 2 O 3 powders. Titanium(IV) butoxide, telluric(VI) acid and boric acid were used as precursors. Differences were observed in the degree of decomposition of Ti butoxide in the presence of H 3 BO 3 and H 6 TeO 6 acids. The phase transformations of the obtained gels in the temperature range of 200-700 °C were investigated by XRD. Composite materials containing an amorphous phase and different crystalline phases (metallic Te, α-TeO 2 , anatase, rutile and TiTe 3 O 8 ) were prepared. Heating at 400 °C indicated a crystalline-to-amorphous-phase ratio of approximately 3:1. The scanning electron microscopy (SEM) analysis showed the preparation of plate-like TiO 2 nanoparticles. The IR results showed that the short-range order of the amorphous phases that are part of the composite materials consists of TiO 6 , BO 3 , BO 4 and TeO 4 structural units. Free B 2 O 3 was not detected in the investigated compositions which could be related to the better connectivity between the building units as compared to binary TiO 2 /B 2 O 3 compositions. The UV-Vis spectra of the investigated gels exhibited a red shift of the cut-off due to the presence of boron and tellurium units. The binary sample achieved the maximum photodegradation efficiency (94%) toward Malachite green dye under UV irradiation, whereas the ternary sample photoactivity was very low. The compositions exhibited promising antibacterial activity against E. coli NBIMCC K12 407.