One pot facile synthesis of selenium nanostructures by microwave assisted solvothermal process

Abstract

Research in Selenium nanostructures is very much attractive owing to their variety of technological applications. Synthesis of Selenium nanostructures reported in literature is cumbersome due to itscomplex and lengthy synthesis procedures. A one pot facile synthesis by microwave assisted solvothermal reaction is reported in this work. A simple reduction of SeO2 in presence of microwave yields the Se nanostructure of different morphology such as nano particles and different sizes of nanorods. Moreover an extended procedure of aging the end composition in ethanol solvent for 8hrs is observed to yield Se nanoneedles and aging in ethylene glycol(EG) for one week results in the formation of longer nanorods. Structural analysis from powder XRD diffratogram confirms a trigonal unit cell with P3121 space group while the compositional analysis was performed using Energy dispersive X-ray spectroscopy(EDX). Field emission Scanning electron microscope (FESEM) images indicate the presence of nanoflakes of size (400 to 900) nm. However the morphology of sample indicates the presence of only nanorods in needle shape with length (5 to 6) µm and diameter (0.5 to1.30) μm and longer aged sample in EG indicates the presence of nanowires with length of the order of (∼100) μm and diameter of the order of (∼3) μm. Optical band gap obtained from (Kubelka-Munk) plot for investigated samples indicate a direct band gap of around(1.72 to 1.76) eV with an infinitesimal but significant variation betweendifferent morphology samples. This one pot facile, reproducible, scalable and controllable approach using microwave assisted synthesis is promising for tuning the physical and morphological properties of Se nanostructures in the field of thermoelectrics.