Green synthesis of reduced graphene oxide using Persea americana mill. extract: Characterization, oxygen reduction reaction and antibacterial application

Abstract

Reduced graphene oxide (rGO) has garnered tremendous attention due to its salient properties that make it applicable in various electrochemical and environmental remediation fields. However, the commonly used chemical method to obtain rGO from graphene oxide (GO) involves toxic chemicals making both the process and product toxic and expensive. In the present work, the suitability of Avocado (Persea americana Mill) seed extract to reduce as-synthesized GO to rGO was investigated fully by optimising the reducing parameters such as the pH, temperature, amount of extract and reduction time. The formation of rGO from GO was confirmed with UV–Vis spectrophotometry (UV–Vis), Fourier Transform Infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and the thermogravimetric analysis (TGA). The optimal conditions for reducing GO with avocado seed extract are pH 8, 100 °C, and 12 h. The average thickness and width for the rGO was 5.55 nm and 11.39 nm accordingly. While GO exhibited a ζ of −29.9.3 mV, the reduced GO possessed a − 38.2 mV. Calculations from the Kotouckey-Levich's equation demonstrated that the obtained rGO can potentially be applied as an oxygen reduction reaction (ORR) catalyst for the generation of hydrogen peroxide since it follows a 2e⁻ pathway mechanism where hydrogen peroxide is generated as an intermediate. Additionally, the avocado seed extract reduced GO demonstrated a slight growth inhibition of methicillin resistant S. aureus (MRSA).