EFFECT OF SYNTHESIS TEMPERATURE ON THE OPTICAL, STRUCTURAL AND MORPHOLOGICAL PROPERTIES OF GREEN-SYNTHESIZED SILVER NANOPARTICLES USING CANDLE BUSH EXTRACT

There have been impressive developments in the field of green nanotechnology in the recent past years, with numerous methodologies developed to synthesize nanoparticles of particular shape and size, depending on specific requirements. Several factors such as the method used for synthesis, pH, temperature, pressure, reaction time, particle size and pore size greatly influence the quality and quantity of green-synthesized nanoparticles and their applications. This research therefore seeks to study the effect of synthesis temperature on the optical, structural and morphological properties of green-synthesized silver nanoparticles using Candle bush extract. Candle bush leaves extract was prepared and added 1 mM of silver nitrate (AgNO3) solution to synthesize the nanoparticles at 40 oC, 50 oC and 60 oC, respectively. The optical and Fourier Transform Infra-Red (FTIR) characterizations were carried out using UV-Vis and FTIR spectrometers, respectively. The phase identification of the samples was carried out by powder X-Ray Diffraction (XRD) analysis. The surface morphologies and elemental composition of the samples were investigated using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) and Transmission Electron Microscopy (TEM) analyses, respectively. Results showed that the optical absorbance observed at around 425 nm belongs to silver nanoparticles as reported in literature. The FTIR spectra revealed the presence of different functional groups and their possible involvement in the formation and modification of the silver nanoparticles. The XRD patterns were observed to be crystalline in nature. The average crystallite sizes of the nanoparticles were found to be 7.01 nm, 5.73 nm and 5.33 nm for AgNPs synthesized at 40 oC, 50 oC and 60 oC, respectively. The crystallite size reduced greatly when the AgNPs was synthesized at 60 oC. The surface morphologies of the synthesized silver nanoparticles became visible, uniform, and dense, with no significant domains of aggregated particles when the nanoparticles were synthesized at 60 oC. The EDX analyses of the nanoparticles confirmed the presence of Ag, C, O, K, N, S and Si. The characteristic peaks of other elements observed might be due to the nature of the extract used for the synthesis. The TEM images were observed to be spherical in nature. The average particle sizes of the nanoparticles synthesized at 40 oC, 50 oC and 60 oC are 16.16 nm, 8.78 nm and 6.57 nm, respectively. The particle size reduced greatly when the nanoparticle was synthesized at 60 oC which might be due to the effect of the synthesis temperature. From the results, it could be seen that the extract and the nanoparticles possess good properties and great potentials. Thus, the nanoparticles could be recommended for application in dye-sensitized solar cell.