Microbial fuel cell assisted band gap narrowed TiO(2) for visible light-induced photocatalytic activities and power generation

This paper reports a simple, biogenic and green approach to obtain narrow band gap and visible light-active TiO(2) nanoparticles. Commercial white TiO(2) (w-TiO(2)) was treated in the cathode chamber of a Microbial Fuel Cell (MFC), which produced modified light gray TiO(2) (g-TiO(2)) nanoparticles. The DRS, PL, XRD, EPR, HR-TEM, and XPS were performed to understand the band gap decline of g-TiO(2). The optical study revealed a significant decrease in the band gap of the g-TiO(2) (E(g) = 2.80 eV) compared to the w-TiO(2) (E(g) = 3.10 eV). The XPS revealed variations in the surface states, composition, Ti(4+) to Ti(3+) ratio, and oxygen vacancies in the g-TiO(2). The Ti(3+) and oxygen vacancy-induced enhanced visible light photocatalytic activity of g-TiO(2) was confirmed by degrading different model dyes. The enhanced photoelectrochemical response under visible light irradiation further supported the improved performance of the g-TiO(2) owing to a decrease in the electron transfer resistance and an increase in charge transfer rate. During the TiO(2) treatment process, electricity generation in MFC was also observed, which was ~0.3979 V corresponding to a power density of 70.39 mW/m(2). This study confirms narrow band gap TiO(2) can be easily obtained and used effectively as photocatalysts and photoelectrode material.