Fabrication of zinc oxide-decorated phytoreduced graphene oxide nanohybrid via Clerodendrum infortunatum

Abstract

The present paper reports eco-friendly preparation of a mesoporous phytoreduced graphene oxide (rGO)–zinc oxide (ZnO) nanohybrid (NH) using the leaf extract of Clerodendrum infortunatum as a green reducing agent at room temperature. The as-synthesized rGO–zinc oxide NH was characterized by diverse analytical techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy (EDS), ultraviolet-diffuse reflectance spectroscopy (UV-DRS), X-ray photoelectron, Raman spectroscopy, Brunauer–Emmett–Teller (BET) analysis, thermogravimetry and photoluminescence (PL) spectroscopy to study its structure, morphology, surface area, porosity, thermal behavior and optical properties. XRD patterns revealed the decoration of hexagonal wurtzite zinc oxide on the surface of rGO, and its composition was confirmed by EDS. UV-DRS showed slight blueshift of the rGO–zinc oxide NH absorption spectrum, suggesting the successful anchoring of zinc oxide on the rGO surface. The scanning electron microscopy images revealed sheetlike morphology with 20–25 nm thick zinc oxide platelets decorating the rGO surface. Raman shifts showed higher I D/I G ratios for rGO and rGO–zinc oxide than for GO, indicating a decrease in the average size of the sp2-hybrid carbon (C) domain. The BET isotherm confirmed the mesoporous nature of the rGO–zinc oxide NH having average pore size (18 nm) and surface area (67.3 m2/g). The rGO–zinc oxide NH showed diminished PL intensity compared with zinc (Zn), suggesting that the recombination of electron–hole (e−–h+) pairs was effectively reduced. rGO–zinc oxide nanocrystals showed enhanced radical-scavenging activity against 1,1-diphenyl-2-picrylhydrazyl free radicals compared with GO and zinc oxide.