Green Wastes Mediated Zinc Oxide Nanoparticles: Synthesis, Characterization and Electrochemical Studies

Omolola E Fayemi,El-Sayed M Sherif,Eno E Ebenso,Enyioma C Okpara,Harri Junaedi

doi:10.3390/ma13194241

Omolola E Fayemi, El-Sayed M Sherif + Show 3 more

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https://doi.org/10.3390/ma13194241

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Abstract

Zinc Oxide (ZnO) nanoparticles were prepared using a simple green synthesis approach in an alkaline medium, from three different extracts of citrus peels waste. The synthesized nano-crystalline materials were characterized by using ultraviolet-visible spectroscopy (UV-vis), x-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive x-ray spectroscopy (EDS), environmental scanning electron microscopy (ESEM), and transmission electron microscopy (TEM). UV-vis analysis of the nanoparticles showed broad peaks around 360 nm for the ZnO NPs (Zinc oxide nanoparticles) from three citrus peels’ extracts. ZnO NPs exhibited Zn–O band close to 553 cm−1, which further verified the formation of the ZnO NPs. A bandgap of 3.26 eV, 3.20 eV and 3.30 eV was calculated for the ZnO NPs from grape (ZnO NPs/GPE), lemon (ZnO NPs/LPE), and orange (ZnO NPs/OPE) peels extract, respectively. The average grain sizes of the ZnO nanoparticles were evaluated to be 30.28 nm, 21.98 nm, and 18.49 nm for grape (ZnO NPs/GPE), lemon (ZnO NPs/LPE), and orange (ZnO NPs/OPE) peel extract, respectively. The surface morphology and sizes of the nanoparticle were confirmed by ESEM and TEM analysis, respectively. Furthermore, the zeta potential of the as-prepared ZnO NPs from OPE, LPE, and GPE was −34.2 mV, −38.8 mV, and −42.9 mV, respectively, indicating the high stability of the nanoparticles. Cyclic voltammetric properties of the synthesized nanoparticles were investigated across extracts, and the results showed that the citrus peels extracts (CPE) mediated ZnO NPs modified screen plate carbon (SPC/ ZnO NPs/CPE) electrodes exhibited enhanced catalytic properties when compared with the bare SPCE. The electroactive areas computed from the enhancement of the bare SPCE was approximately three times for SPCE/ ZnO NPs/LPE, and SPCE/ZnO NPs/GPE, and two times for SPCE/ZnO NPs/OPE, higher than that of the bare SPCE. Comparison across the extracts suggested that the catalytic properties of the nanoparticles were unique in ZnO NPs from GPE.

Highlights

Nanotechnology involves methods of fabrication of materials at the lowest scale possible [1].The primary purpose of nanotechnology is essentially nanoparticles synthesis [2]
The synthesized Zinc Oxide (ZnO) NPs/GPE showed a broad absorbance peak with redshifts at 348 nm, 360 nm, and 366 nm within 10 min, 1–3 h, and 4–5 h (Figure 2a) of synthesis, which is ascribed to the agglomeration of Zinc oxide nanoparticles (ZnO NPs), leading to the rise in the size of the particles with more time of interaction between the plant and metal salt precursors [37]
Three citrus species were used in the synthesis of ZnO NPs in the presence NaOH and were characterized as summarized in Tables 4 and 5

Summary

Introduction

The primary purpose of nanotechnology is essentially nanoparticles synthesis [2]. Owing to their unique catalytic, mechanical, thermal, electrical and optical properties being different and better than their bulk counterpart, they have potential and growing applications in diverse fields [3,4]. The addition in surface area to volume ratio, as a rule, changes the catalytic, and thermal properties of the material [5]. The combined effect of nanomaterials and electrochemical sensor materials would result in advantageous and expanding sensing applications [7,8]. Nanostructured material sensors exploit the advantages of the amplified electrode (electroactive) surface area, fast rate of electron transfer, and enhanced rate of mass transport in comparison to bulk electrode materials [7]

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