Biological synthesis of nanostructured ZnO as a solar-light driven photocatalyst and antimicrobial agent

Abstract

A good photocatalyst should have a high surface area, a substantial absorption capacity, and a visible light active bandgap. Semi-conductive materials, particularly nanostructured ones, have recently received more attention for photocatalytic applications since they have nearly all of the properties of a perfect photocatalyst. Therefore, modern material scientists attempt to develop a cost-effective and environmentally acceptable method for nanoscale fabrication of semi-conductive materials. Herein, we fabricate a two-dimensional (2D) nanoarchitecture of ZnO by reducing zinc nitrate precursor using plant extract (Cleome brachycarpa). Flavonoids are antioxidants that are found in high amounts in the roots, leaves, and stems of Cleome brachycarpa. Crystal structure, morphological characteristics, elemental compositions, and functional group analyses of the as-synthesized ZnO sample were carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared (FTIR), and other techniques. XRD analysis confirmed that ZnO with a nano-crystallite size (18.377 nm) and a wurtzite phase had been formed successfully. The FTIR and UV–visible analyses of the as-prepared ZnO nanoarchitecture verify the nanoarchitecture's Zn–O vibrational mode and visible light-triggered band gap (2.89 eV), respectively. SEM and EDX examinations validated the sample's two-dimensional nanoarchitecture and impurity-free chemical composition, respectively. The photocatalytic efficiency of the ZnO was analyzed under solar against crystal violet dye (CV) for 70 min. Briefly, the nanostructured ZnO catalyst eliminated 88.4% CV (mineralization + adsorption) at the rate constant (k) of 0.022 min-1. Agar well diffusion was employed to evaluate the antibacterial potential of the produced ZnO sample, which proved to be effective against both G + ive and G-ive bacterial strains. ZnO's exceptional photo-mineralization and antibacterial characteristics are owing to its innovative 2D nanoarchitecture, and visible-light triggered bandgap. The production of nanostructured semi-conductive materials from naturally occurring plant products might be advocated as an environmentally friendly alternative to chemical techniques in the future.