Influence of Adansonia digitata Stem Extract Immersion Time on Properties of Biosynthesised Silver Nanoparticles

Abstract

The emergence of the multidisciplinary field of nanoscience with potential applications in medicine, cosmetics, renewable energy, agriculture and environmental remediation has led scientists to search for safer methods of synthesising nanoparticles. We based this study on the synthesis of silver nanoparticles (AgNPs) for varying immersion times of 30, 60, 90, 120 and 150 min, while employing Adansonia digitata as a reducing and capping agent and labelled A, B, C, D and E, respectively. The X-ray diffraction (XRD) pattern of the synthesised AgNPs for all samples have three peaks positioned at 2θ = 37.94°, 44.07° and 64.37° corresponding to (111), (200) and (220) planes, respectively. The samples have a preferred orientation at 2θ = 37.94° corresponding to (111) plane irrespective of the duration of immersion of Adansonia digitata root extracts. The preferred intense peak shows a polycrystalline phase composition of the green synthesised AgNPs, demonstrating the creation of face-centred cubic crystalline of AgNPs. The intrinsic stress, σs, dislocation density, δ, specific surface area, S, crystallite size (D), surface area (S) to volume (V) ratio, lattice parameter, a and atomic packing factor were calculated from XRD data and presented. The particle sizes obtained from the SEM analysis are 69.88, 18.69, 15.45, 19.64 and 20.08 nm for samples A, B, C, D and E, respectively. The optical energy band gaps are 2.37 eV, 2.42 eV, 2.59 eV, 2.52 eV and 2.34 eV for samples A, B, C, D and E respectively. The synthesised AgNPs can be used in energy storage and conversions owing to their properties.