Magnetron co-sputtered Bi12TiO20/Bi4Ti3O12 composite – An efficient photocatalytic material with photoinduced oxygen vacancies for water treatment application

Photocatalytic degradation of contaminants of emerging concern using a low-cost and efficient black bismuth titanate-based water treatment reactor

“…In a previous study, a bismuth titanate composite, produced by magnetron sputtering, outperformed TiO2 for both dye degradation and E. coli inactivation tests under UV-A [51]. Bismuth titanate was as much as 15 times more efficient at degrading MB under UV than anatase TiO2 [51]. Furthermore, upon prolonged use bismuth titanate coatings have shown the remarkable property of producing photoinduced oxygen vacancies, which directly translated to a 6-fold increase in performance after 15 consecutive cycling tests.…”

“…The magnetrons were powered by a dual channel Advanced Energy Pinnacle Plus power supply in pulsed DC mode operating at a frequency of 100 kHz and 60% duty. Powers of 750 and 185 W were applied to the titanium and bismuth target, respectively, to achieve the stoichiometry required to deposit Bi12TiO20 thin films, based on previous findings [51]. The Bi12TiO20 photocatalyst was deposited on the surface of two opposite sides of AR-Glas™ Stirring Rods (length: 250 mm, diameter 6 mm), for 4 h each, over a 250 mm length (purchased from the Fisher).…”

“…Contrary to LCPR-I, the present photocatalytic reactor utilises coated glass rods as the photocatalyst. Additionally, TiO2 was substituted with bismuth titanate, a more efficient and promising photocatalyst [51]. Figure 1 provides a schematic representation of the bespoke water treatment photocatalytic reactor loaded with bismuth titanate coated glass stirring rods and a photograph of the separate components.…”

“…Kallawar et al reported that the bandgap values for the Bi12TiO20 polymorph range from 2.36 to 2.78 eV, which makes it a suitable candidate for visible-light photocatalysis [50]. In a previous study, a bismuth titanate composite, produced by magnetron sputtering, outperformed TiO2 for both dye degradation and E. coli inactivation tests under UV-A [51]. Bismuth titanate was as much as 15 times more efficient at degrading MB under UV than anatase TiO2 [51].…”

“…Defects can be induced in TiO2 through a plethora of methods such as metal reduction, ionothermal processes, plasma assisted processes, NaBH4 (sodium borohydride) reduction, microwave radiation, laser ablation, ultrasonication, electrochemical reduction etc [52]. In bismuth titanate, UV irradiation alone was sufficient to induce oxygen vacancies, resulting in significantly increased photocatalytic activity, which means that in practice, one only has to use this photocatalyst to improve its performance [51]. The mechanism behind the oxygen vacancy formation is not yet understood, but Ye et al attributed it to the low bond energy and long bond length of the Bi−O bond [54].…”