Abstract
Manganese dioxide (MnO2) nanoparticles were synthesised by the reduction of potassium permanganate (KMnO4) using Kalopanax pictus leaf extract at room temperature. A transparent dark-brown colour appeared after the addition of K. pictus leaf extract to the solution of permanganate. The time course of the reduction of KMnO4 and synthesis of MnO2 nanoparticles was monitored by means of UV–Vis spectra. The reduction of KMnO4 occurred after addition of plant extract with disappearance of KMnO4 specific peaks and emergence of peak specific for MnO2 nanoparticles. MnO2 nanoparticles showed absorption maxima at 404 nm. The electron dispersive X-ray spectroscopy analyses confirmed the presence of Mn and O in the sample. X-ray photoelectron spectroscopy revealed characteristic binding energies for MnO2 nanoparticles. Transmission electron microscopy micrographs revealed presence of uniformly dispersed spherical shaped particles with average size of 19.2 nm. The selected area electron diffraction patterns revealed the crystalline nature of MnO2 nanoparticles. Fourier transform-infrared spectroscopy spectra of pure MnO2 show the occurrence of O–Mn–O vibrational mode at around 518 cm−1. The phyto-synthesised MnO2 nanoparticles showed degradation ability of dyes (congo red and safranin O) similar to chemically synthesised MnO2 nanoparticles. This study shows simple and eco-friendly synthesis of MnO2 nanoparticles by plant extract and their utilisation for dye degradation for the first time.