Biosynthesis of Titanium Oxide Nanoparticles Using Root Extract of Kniphofia Foliosa and its Application for Dye Sensitized Solar Cell

Abstract

Currently synthesis of nanoparticles (NPs) using plant extracts has attracted a great attention due to its low cost, non-toxicity and environment-friendly nature. In this study pure titanium dioxide NPs were synthesized by biological methods using 0.4 M titanium tetra butoxide as a precursor with the presence of ethanolic root extract of kniphofia foliosa in different ratio and the biosynthesized NPs were tested for their application in dye sensitized solar cells (DSSCs). The biosynthesized NPs were characterized by thermogravimetric analysis (TGA-DTA), X-ray diffraction (XRD), scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), ultraviolet visible spectroscopy (UV-Vis) and fourier transformer infrared spectroscopy (FTIR). TGA was performed to study the thermal stability of pure TiO2 NPs and the NPs were stable above 500 ℃ . The crystal structure of the NPs were followed by XRD analysis and the analysis revealed that the biosynthesized NPs have particle size in the range of 8.17 - 10.15 nm. SEM analysis indicated that the biosynthesized NPs posses spherical in shape. The EDS analysis revealed the presence of only Ti and O in the prepared nano samples confirming the purity of the biosynthesized NPs. TEM analysis shows the internal structure of the nanoparticles as spherical. The UV-Vis investigation confirmes the formation of titanium oxide NPs, the absorbance peak was exist in between 298 nm - 314 nm. FTIR study confirmed the presence of amines,carboxylic acids, phenols, alcohols, protiens, enzymes. The pastes of biosynthesized NPs were used as photoanodes in DSSCs (a device used for converting absorbed light in to electricity). In this study natural sensitizer was extracted from roots of kniphofia schemperi using absolute ethanol (99.9%) as a solvent and in addition to this, 0.001 M crystal violet dye was prepared. At the end, devices were fabricated using k.schemperi and crystal violet and TiO2 (1:1, 2:1 and 1:2) photoelectrodes which showed the power conversion efficiency of 0.117%, 1.3% and 0.039%, respectively. IPCE analysis of the biosynthesized TiO2 (2:1, 1:2 and 1:1) photoelectrode shows 18.01%, 6.64% and 2.66%, respectively.