Mangifera indica mediated biogenic synthesis of undoped and doped tio2 nanoparticles and evaluation of their structural, morphological, photocatalytic and antibacterial properties

Abstract

Pristine and doped TiO¬¬2 nanoparticles were synthesized utilizing mango leaf extract via a cost effective and eco-friendly biogenic route. As a precursor, titanium isopropoxide (TTIP) was used. The transition metals, Cu and Ag, were added as dopant materials in various concentration levels of 0.5%, 1%, 1.5%, and 2%. To assess the morphological, structural, photocatalytic, and antibacterial properties of the prepared samples, several characterization techniques such as SEM, EDX, XRD, UV-Vis, Kirby-Bauer disk diffusion method were implemented. The observation from SEM analysis revealed that compared to undoped TiO¬2¬, Cu- and Ag-doped TiO2 nanoparticles showed agglomeration. Evaluation of elemental analysis by EDX confirmed the doping of Cu2+ and Ag+ ions in the TiO2 lattice structure. It also ensured the absence of any kind of impurities. According to XRD analysis, pure TiO2 as well as Cu- and Ag-doped TiO¬2 nanoparticles exhibited formation of anatase phase without any rutile phase. Crystallite size and micro-strain of the prepared nanoparticles were determined from XRD results along with W-H plot. At maximum doping percentage (2%), both Cu- and Ag-doped TiO2 samples showed reduction in crystallite size compared to pure TiO2. UV-Vis spectroscopy was employed to determine the band gap and photocatalytic efficiency of the prepared samples. Both Cu- and Ag-doped TiO2 samples showed a gradual decline in band gap in comparison to undoped TiO2 with the increasing doping percentage. The result of the photo-degradation of methylene blue (MB) demonstrated that doping of TiO2, whether with Cu/Ag, greatly enhance the photocatalytic performance which is attribute to the “Red-Shift” phenomena along with the reduced photo-generated electron-hole recombination rate. Antibacterial performance of the prepared samples was examined against Gram positive and Gram negative bacteria strain utilizing Kirby-Bauer disk diffusion technique. Cu- and Ag- doped TiO2 nanoparticles of specific doping percentage showed mentionable zone of inhibition confirming their potential as bactericidal agent. Results obtained suggest that TiO2 nanoparticles (both undoped and doped) synthesized through a greener approach may have a promising future for water purification, dye remediation, medical sector and food industry owing to better photo-degradation and antibacterial activity. Keywords: TiO2 nanoparticles, Mango leaf extract, Biogenic route, Photocatalytic activity, Antibacterial activity.