Citation: Albalawi, I.; Alatawi, H.;
Alsefri, S.; Moore, E. Electrochemical
Synthesis of Reduced Graphene
Oxide/Gold Nanoparticles in a
Single Step for Carbaryl Detection in
Water. Sensors 2022, 22, 5251.
https://doi.org/10.3390/s22145251
Academic Editor: Boris N. Khlebtsov
Received: 26 May 2022
Accepted: 11 July 2022
Published: 13 July 2022
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Article
Electrochemical Synthesis of Reduced Graphene Oxide/Gold
Nanoparticles in a Single Step for Carbaryl Detection in Water
Ibtihaj Albalawi , Hanan Alatawi , Samia Alsefri and Eric Moore *
Sensing and Separation Group, School of Chemistry, University College Cork, T12 YN60 Cork, Ireland;
110125574@umail.ucc.ie (I.A.); 110122737@umail.ucc.ie (H.A.); 112220405@umail.ucc.ie (S.A.)
* Correspondence: e.moore@ucc.ie
Abstract:
In this study, an in situ synthesis approach based on electrochemical reduction and ion
exchange was employed to detect carbaryl species using a disposable, screen-printed carbon electrode
fabricated with nanocomposite materials. Reduced graphene oxide (rGO) was used to create a larger
electrode surface and more active sites. Gold nanoparticles (AuNPs,) were incorporated to accelerate
electron transfer and enhance sensitivity. A cation exchange Nafion polymer was used to enable the
adhesion of rGO and AuNPs to the electrode surface and speed up ion exchange. Cyclic voltammetry
(CV), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), electrical
impedance spectroscopy (EIS), atomic force microscopy (AFM) and scanning electron microscopy
(SEM) were performed to study the electrochemical and physical properties of the modified sensor. In
the presence of differential pulse voltammetry (DPV), an rGO/AuNP/Nafion-modified electrode was
effectively used to measure the carbaryl concentration in river and tap water samples. The developed
sensor exhibited superior electrochemical performance in terms of reproducibility, stability, efficiency
and selectivity for carbaryl detection with a detection limit of 0.2
µ
M and a concentration range
between 0.5
µ
M and 250
µ
M. The proposed approach was compared to capillary electrophoresis with
ultraviolet detection (CE-UV).
Keywords:
in situ synthesis approach; screen-printed carbon electrode; carbaryl–phenol; reduced
graphene oxide (rGO); gold nanoparticles (AuNPs); environmental water
1. Introduction
Pesticide use in grains is extensively reported, and this trend is likely to expand
significantly over the next few decades [
1
]. According to a World Health Organization
(WHO) report, roughly 87,000 cases of cancer that occur each year in poor nations are
linked to pesticide use [
2
]. Among pesticides, carbamate compounds, which have great
insecticidal activity, are the most extensively used pesticides in agriculture [
3
]. Carbaryl
(C
12
H
11
NO
2
) is such a carbamate, which is frequently used in grains and is the second
most common pesticide found in water. These toxic pesticides reach the human body
via drinking water or the food chain and are rapidly absorbed and metabolized in the
gastrointestinal system and, thus, pose a threat to human health due to their toxicity to the
enzyme acetylcholinesterase (AChE), which is necessary for the healthy functioning of the
human central nervous system [
1
,
4
]. Therefore, the sensitive, precise and quick detection
of these carbamate pesticides is critical for environmental and human health protection.
Chromatography is frequently used to identify the presence of insecticides such as
carbaryl in water and soil samples. Among the most often and recently used types of chro-
matography are chromatography coupled to mass spectroscopy [
5
,
6
], gas chromatography
(GC) [
7
], high-performance liquid chromatography (HPLC) [
8
] and capillary electrophore-
sis (CE) [
9
]. However, there are several limitations to these methods, including: they are
time-consuming; significant quantities of solvents are consumed; and precise extraction
and cleaning procedures are required, making them complex and consequently inadequate
Sensors 2022, 22, 5251. https://doi.org/10.3390/s22145251 https://www.mdpi.com/journal/sensors
