Green synthesis of graphene/zinc oxide nanocomposite for Optoelectronic Applications

Abstract

This research presents a green synthesis of high-quality graphene (G), zinc oxide (ZnO) and graphene/zinc oxide (G/ZnO) nanocomposites. Zinc Oxide nanoparticles (ZnO NPs) were synthesised using Amarus Pinnantum extracts, while graphene was derived from Bryophyllum Pinnatum shoot plant extracts. The integration of graphene into the ZnO matrix was investigated to enhance its structural, optical, and electrical properties, particularly electron mobility. The synthesised materials were characterised using UV-Vis spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS). UV-Vis spectra revealed characteristic absorption bands for graphene, ZnO, and G/ZnO. FTIR analysis confirmed the presence of functional groups associated with each material, including 593 cm-1 (Zn-O bending vibrations), 1088 and 1459 cm-1 (C-H Alkyl group bending vibrations), 1583 cm-1 (C=C Aromatic stretching vibration), and 3467 and 3777 cm-1 (O-H Hydroxyl group stretching vibration) in the G/ZnO nanocomposites. Scanning Electron Microscopy (SEM) images showed spherical zinc oxide (ZnO) nanoparticles, a rough, flake-like graphene structure, and a porous, aggregated morphology for the G/ZnO nanocomposite. EDS analysis verified the elemental composition of the materials. The electrical properties of the G/ZnO nanocomposite were significantly improved compared to pure graphene and ZnO nanoparticles. The composite exhibited a higher current (4.62 μA) and lower resistivity (405.56 Ω·m) at a specific voltage (0.60 V). This enhancement is attributed to the formation of a percolative network within the composite, which facilitates efficient charge transfer and improves electron mobility. These findings suggest that the G/ZnO nanocomposite holds promise for applications in optoelectronic devices.