Efficient photocatalytic bactericidal performance of green-synthesised TiO2/reduced graphene oxide using banana peel extracts

Photocatalytic materials have great potential as efficient bactericides to inactivate a variety of harmful microorganisms. We conducted experiments involving TiO2/rGO biosynthesis using banana peel extracts (Musa paradisiaca L.) for photoinactivation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Graphite oxide (GO) synthesis followed the Tour method, and reduced graphene oxide (rGO) synthesis employed banana peel extracts as a reducing agent. Incorporation of TiO2 into rGO was accomplished through a hydrothermal process. X-Ray diffraction (XRD) analysis demonstrated that the composite was in the rutile phase, with a diffraction peak at 2θ = 27.481° and a crystal size of 83.375 nm. Gas sorption analyzer scanning (GSA) analysis revealed that TiO2/rGO exhibited characteristics of type IV (mesoporous), while the BJH curve displayed heterogeneous pore distribution and a surface area of 22.664 m2/g. Fourier transform Infrared (FTIR) results unveiled the characteristic Ti-O-Ti vibrations of TiO2 at 648.96 cm-1. Ultraviolet-Visible diffuse reflectance spectroscopy (UV-Vis DR) measurements yielded band gap energies of 3.052 eV for TiO2/rGO. Scanning electron microscope (SEM) imaging illustrated the morphology of TiO2/rGO, manifesting as unevenly sized white lumps. The composition analysis using EDX identified carbon, oxygen, titanium, and aluminum as the elemental constituents. Transmission electron microscope (TEM) observations portrayed the morphology of TiO2/rGO composites, presenting rGO sheets and spherical TiO2 lumps. For assessing photoinactivation, experiments were performed on E. coli and S. aureus using the disc method, with sunlight irradiation proving most effective in achieving optimal results during 6 h and 4 h, respectively.