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(A) CV analysis using Ag electrode (black) and Ag electrode with electrodeposited Cu modification (Ag/Cu, red) in a blank solution (0 mM of NO 3 − ) of 0.1 M KCl electrolyte. (B) CV analysis of Ag (black) and Ag/Cu (red) with the presence of 3 mM NO 3 − in 0.1 M KCl. Screenprinted AgCl was used as the RE.
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Nitrate (NO3–) contamination is becoming a major concern due to the negative effects of an excessive NO3– presence in water which can have detrimental effects on human health. Sensitive, real-time, low-cost, and portable measurement systems able to detect extremely low concentrations of NO3– in water are thus becoming extremely important. In this w...
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... the observation was quite similar to that of Chen et al. 34 who showed that the morphology of the Cu deposited by electrocrystallization is controlled by the different surface energies of the crystallographic plane. 35 The composition of the surface of the WE estimated by performing energydispersive X-ray spectroscopy (EDS) analysis is presented in Figure S3. The analysis of the considered EDS peaks reveals concentrations of 80% of Cu, 15% of Ag, 4% of C, and 0.5% of O, which are in the expected range, considering the type of deposition and processes used to fabricate the sample, and also reveals that most of the electrode is well covered with electrodeposited Cu. ...
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... Characterization. Figure 3A shows the CV obtained at a scan rate of 100 mV for the bare Ag electrode and the Cu/Ag electrode in a blank solution (0 mM NO 3 − in 0.1 M KCl). In the case of the bare Ag electrode, the curve shows a reduction peak at −1.15 V due to the reduction of Ag, which disappears in the case of the Ag/Cu electrode, proving the full Cu coverage. ...
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... the addition of 3 mM NO 3 − in the electrolyte solution, the CV of the bare Ag electrode remains unchanged; instead, two additional reduction peaks (E 3 and E 4 ) appeared for the Ag/Cu electrode ( Figure 3B) which correspond to the reduction of NO 3 − (E 3 ) and NO 2 − (E 4 ) ions that happen consecutively. 36 Indeed, as described by eqs 3 and 4, the primary product of NO 3 − reduction is NO 2 − , which is in turn reduced to form NH 3 during the potential scan 37 ...
Citations
... The P(Py-co-PyCOOH)-based potentiometric sensor exhibited comparable or superior sensing performances toward nitrate. Furthermore, the maximum contaminant level of nitrate in public drinking water has been established by World Health Organization and European Directives to be 50 mg l −1 (about 8 × 10 -4 M). 46 The P(Py-co-PyCOOH)-based potentiometric sensor had a wide linear range to cover this maximum contaminant level. ...
In typical solid-contact potentiometric sensing, ion selective membranes (ISMs) play the role of recognizing the target analytes. A variety of solid-contact materials have been utilized to realize the ion-to-electron transduction. However, the ISMs show some drawbacks during practical application. Recent research efforts have been devoted to developing ISM-free potentiometric sensing. In this work, an ion-imprinted conducting poly (pyrrole-co-pyrrole-3-carboxylic acid) copolymer was investigated to achieve the ISM-free potentiometric sensing toward nitrate, an important anion to monitor in the environment. The copolymer-based electrochemical sensor afforded good potentiometric responses toward nitrate in a Nernstian manner, exhibiting superior or comparable sensing performances with existing ISM-based potentiometric sensors. Compared with polypyrrole homopolymer, the introduced carboxylate group in the side chain of the copolymer was likely to contribute to the redox activity, enabling better ion-to-electron transduction. More importantly, a unique self-doped effect was observed in the prepared poly (pyrrole-co-pyrrole-3-carboxylic acid), extending the working pH range of polypyrrole family and providing potential implications to develop electrochemical sensors when the environmental pH matters.
... The incorporation of SPEs into electrochemical analyses has resulted in the development of integrated systems that have successfully commercialized and provide, rapid, selective, and accurate analytical tools 11,12 . Electrochemical methods have become increasingly prevalent in numerous areas, including environmental 13,14 and food analysis [15][16][17] , medical diagnostics 18,19 , pharmaceutical analysis 20 , waste management, cellular analysis, and agriculture 21 . In the realm of electrochemical measurements, potentiometry, amperometry, cyclic voltammetry (CV), differential pulse voltammetry (DPV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) techniques are frequently employed. ...
... As shown in Figure 5CÀ D and S1, the presence of interferents such as NO 2 À , SO 4 2À , Ca 2 + , Cu 2 + , Cl À , Na + , Mg 2 + and HCO 3 À was negligible, as expected for coppermodified sensors. [48,49] Along interference effects, the stability of the device was evaluated ( Figure S2) as a key parameter for environmental monitoring applications. Overall, this sensor proved to be robust and reliable. ...
Nitrates (NO3‐) are crucial in agricultural practices and the food industry, but their excessive presence in water can lead to adverse health effects. Their leaching into water sources necessitates regular monitoring. This study introduces a novel bimodal electrochemical (EC)/photoelectrochemical (PEC) sensor, utilizing copper‐modified graphitic carbon nitride (Cu/g‐C3N4), designed for precise nitrate determination. The structural morphology and chemical composition of the Cu/g‐C3N4 nanocomposite were meticulously examined using Transmission Electron Microscopy (TEM) and Fourier‐transform infrared spectroscopy (FTIR). The optimization of copper loading in g‐C3N4 was conducted, and the electrochemical behavior and light irradiation interaction of various Cu/g‐C3N4 nanocomposites were systematically studied. The investigation revealed that 20 % Cu/g‐C3N4 represented the optimal doping ratio, establishing the most promising candidate for NO3‐. Nitrates were consistently measured using both EC and PEC techniques, yielding Limits of Detection (LoD) of 3.75 and 9.60 ppm, respectively. The sensor‘s robust performance was further demonstrated in the presence of possible interferents. The proposed sensors were also successfully used to detect NO3‐ in commercial water. This bimodal sensor presents a promising approach for accurate nitrate determination, attesting to its potential for effective cross‐validation.
... Researchers showed that Cu deposition, increasing the electroactive surface area of the working electrode, lowers the LoD of electrochemical NO 3 − sensors. For instance, Inam et al. [86] developed a flexible screen-printed amperometric NO 3 − sensor, functionalized with copper nanoclusters deposited via cyclic voltammetry on silver WE. The obtained copper nanocluster morphology and size were uniform all over the Ag surface (Figure 6a). ...
... (a) SEM micrograph of Cu/Ag surface characterized by a uniform deposition of Cu nanoclusters; (b) Calibration curve of the Cu/Ag sensor for NO 3 − detection in water.Reprinted with permission from Inam et al.[86]. ...
This chapter aims to provide information on the progress of research into water quality analyses, providing an overview of the state of the art, including novel research achievements, in the detection of water contaminants. After a brief introduction to the main sensing systems’ characteristics, the attention will be devoted to two different classes of pollutants: organic and inorganic. Microbiological analyses concerning the monitoring of bacterial load in water and chemical analyses with a special focus on mercury, related to heavy metal pollution, and nitrogen compounds, i.e. nitrate ion and ammonium ion, are discussed. Particular attention will be devoted to all sensing systems that are in principle portable and able to make real-time measurements in situ.
... The obtained results agree with those reported by Inam et al. [32] and Lotfi Zadeh Zhad et al. [33]. ...
... Metallic copper is effective in promoting nitrate reduction due to its excellent electrical conductivity and abundance of (d) The obtained XRD patterns confirm the successful deposition of crystalline Cu on the surface of the carbon working electrode. This observation is consistent with previous studies by Inam et al. [32] and Chen et al. [29], which demonstrated that copper electrocrystallization is influenced by the surface energies of different crystallographic planes. Consequently, XRD measurements provide insight into not only metallic copper but also other copper compounds present in the sample. ...
Copper is efficient, has a high conductivity (5.8 × 10⁷ S/m), and is cost-effective. The use of copper-based catalysts is promising for the electrocatalytic reduction of nitrates. This work aims to grow and characterize copper micro-crystals on Screen-Printed Electrodes (SPEs) for NO3⁻ reduction in water. Copper micro-crystals were grown by cyclic voltammetry. Different cycles (2, 5, 7, 10, 12, 15) of copper electrodeposition were investigated (potential ranges from −1.0 V to 0.0 V, scan rate of 0.1 V s⁻¹). Electrodeposition generated different morphologies of copper crystals on the electrodes, as a function of the number of cycles, with various performances. The presence of numerous edges and defects in the copper micro-crystal structures creates highly reactive active sites, thus favoring nitrate reduction. The manufactured material can be successfully employed for environmental applications.
... 26,27 LIG consists of a porous multilayer graphene bonded with sp 2 -bonded carbon atoms and provides high conductivity and surface area for electrochemical sensors 28 and there have been several LIGbased electrochemical sensors to detect targets with good sensing properties, reproducibility, and stability. 29,30 Concerning the detection of nitrite, gold (Au), 31 silver (Ag), 32 copper (Cu), 33 and cobalt (Co) nanoparticles (NPs) have been investigated by combining with different carbon nanomaterials. 12,34 The reason is that only carbon materials suffer from poor electrocatalytic activity. ...
We have recently reported laser-induced fibers (LIF) as a promising nanomaterial that possesses good electrochemical activity and are easily manufacturable. In this paper, for the first time, the application of LIF as functionalization materials on laser-induced graphene (LIG) electrodes for the detection of nitrate is demonstrated. The as-fabricated LIF surfaces on Kapton were extracted by ultrasonication as a dispersion and were used to modify the surface of the LIG electrode. An enhancement in active surface area from 0.669 cm² for bare LIG to 0.83 cm² for LIF-modified LIG was observed. Similarly, the heterogeneous electron transfer rate increased from 0.190 to 0.346 cm s⁻¹ for LIF/LIG electrodes. The electrochemical detection of nitrite was achieved by modifying the LIG with a nanocomposite of LIF and copper phthalocyanine (CuPc). The presence of CuPc provided the desired catalytic activity towards the oxidation of nitrite, and the LIF enhanced the electron transfer to the electrode. Such a synergetic combination of the LIF embedded with CuPc enabled reaching a low limit of detection (LoD) of 0.12 μM, a large linear range from 10 to 10 000 μM and good selectivity in the presence of potential interferants. The sensor had a long shelf life of 30 days and good analytical capability to detect nitrite in mineral, tap, and groundwater. The potential of LIF is largely unexplored and the findings reported here on the fibers would open manifold opportunities for realizing novel applications.
... [78] As shown within Figure 5B, a mixed self-assembled monolayer with thiolated aptamer and a ternary self-assembled monolayer with aptamer, 1,6-hexanethiol (HDT) and 1-mercapto-6-hexanol (MCH) were prepared. Using EIS, the authors showed that the sensor can measure HER2 protein over Gold Thioridazine -10 pM-20 nM 2.9 pM [73] Gold Chromium (VI) -10-50 μM 2.6 μM [74] Gold Arsenic (III) -0-20 μg/L 0.8 μg/L [75] Gold Monosaccharides (glucose and fructose) [77] Gold HER2 protein Aptamer/MCH/HDT 1 pg/mL-1 μg/mL 172 pg/mL [78] Gold Vaspin Coccolith shell/aptamer 2-16 nM 298 pM [79] Gold Thiocholine Cysteamine/glutaraldehyde/AChE -40 μg/L [80] Gold Silver L-lactic acid Mercury 40-500 μM 12 μM [89] Silver Nitrate Copper nanoparticles 0.05-5 mM 0.20 nM [90] Silver Chlorpyrifos 11-MUA/EDC/NHS/aptamer 1-10 5 ng/mL 0.097 ng/mL [91] Silver Cystine -2.4-48 mg/dL 0.65 mg/dL the range of 1 pg/mL-1 μg/mL and a LoD of 172 pg/mL within undiluted human serum. This work provides a strategy to measure a breast cancer marker and could be a promising tool for point-of-care detection and application. ...
Screen‐printed electrochemical sensing platforms are ubiquitous within the field of electrochemistry where they provide benefits of being disposable, cost‐effective, reproducible, easily customisable, portable and allow one to transfer the laboratory approach into the field. In this review, we introduce the concept of screen‐printed electrodes, we summarise positive and negative aspects before moving into the current highlights of using traditional screen‐printed carbon electrodes within the field of electroanalysis. We then look to cover metallic and bulk modified varieties, geometric changes (micro, microband and associated arrays), electrode activation and finally the physical length of screen‐printed electrodes, providing insights for future research.
... For instance, a flexible screen-printed amperomeric electrochemical NO 3 − sensor was developed and functionalized with Cu metal nanoclusters electrodeposited on Ag working electrodes. It showed a high capability to detect NO 3 − in water with a low calculated LoD 0.207 nM (or 0.012 µg/L) and a dynamic concentration range from 50 to 500 µM (or 31 to 310 mg/L) using linear sweep voltammetry (LSV) [23]. In addition, nitrate detection was investigated using commercial single-walled carbon nanotube-modified Cu and Pd-Cu electrodes in a sulfuric acid solution by LSV. ...
... The modified electrode shows peaks at positions (2θ) of 46.3°, corresponding to CuCl(220). This pattern confirms the successful coverage with crystalline Cu on top of the C WE. Additionally, the observation is analogous to that of Inam et al. [23] and Chen et al. [32], who demonstrated that the morphology of Cu electro-crystallization is driven by the surface energy differences in the crystallographic planes. The high-index facet exhibits a high density of low-coordinated atoms, providing more catalytic sites for electrocatalysts [33]. ...
... This characteristic behavior is associated with a diffusion-controlled irreversible electron transfer process [31]. Figure 4b summarizes the This pattern confirms the successful coverage with crystalline Cu on top of the C WE. Additionally, the observation is analogous to that of Inam et al. [23] and Chen et al. [32], who demonstrated that the morphology of Cu electro-crystallization is driven by the surface energy differences in the crystallographic planes. The high-index facet exhibits a high density of low-coordinated atoms, providing more catalytic sites for electrocatalysts [33]. ...
The progressive increase in nitrate’s (NO3−) presence in surface and groundwater enhances environmental and human health risks. The aim of this work is the fabrication and characterization of sensitive, real-time, low-cost, and portable amperometric sensors for low NO3− concentration detection in water. Copper (Cu) micro-flowers were electrodeposited on top of carbon screen-printed electrodes (SPCEs) via cyclic voltammetry (with voltage ranging from −1.0 V to 0.0 V at a scan rate of 0.1 V s−1). The obtained sensors exhibited a high catalytic activity toward the electro-reduction in NO3−, with a sensitivity of 44.71 μA/mM. They had a limit of detection of 0.87 µM and a good dynamic linear concentration range from 0.05 to 3 mM. The results were compared to spectrophotometric analysis. In addition, the devices exhibited good stability and a maximum standard deviation (RSD) of 5% after ten measurements; reproducibility, with a maximum RSD of 4%; and repeatability after 10 measurements with the RSD at only 5.63%.
... reported in the literature [4,12,40]. Fig. S5 illustrates the voltammetric profile of 100 mg L −1 NO 3 − in 0.1 mol L −1 NaCl (supporting electrolyte) acquired on both electrode surfaces. As can be noted, the non-modified surface (CB-PLA (black line)) provided a discrete and poorly defined peak for NO 3 − reduction, on the other hand, the modified surface with AgPs provided a well-defined and sharp peak (around 16.5fold higher than the non-modified surface in terms of current density (j)) at around −1.08 V vs. Ag|AgCl|KCl (sat.) . ...
... Additionally, the selectivity of developed method was checked in the presence of other ions routinely found with NO 3 − in water samples, such as phosphate, ammonium, nitrite, magnesium, chloride, sulfate and heavy metals (Pb 2+ and Cu 2+ ) (Fig. S8) [11,43]. Specifically for phosphate, ammonium, nitrite, magnesium, chloride, and sulfate, voltammograms were recorded using 1:1 ratio concentration between NO 3 − and interfering species as suggested in previous works [40,44,45]. On the other hand, a ratio of 1:0.001 between NO 3 − and heavy metals was used, since Cu 2+ and Pb 2+ are found at trace levels in water samples [46,47]. ...
... Although the works already published present relevant results, it is possible to conclude that CB-PLA/AgPs performed similarly to the following sensors in terms of linear range and LOD values. Considering sensitivity, the sensor offered inferior results to some electrodes modified with a variety of materials [4,40,48,50,51], but comparable with other silver-based sensors [12,49]. Importantly, the proposed device was advantageous regarding proper selectivity (interference-free), fast response, and easy handling. ...
Monitoring nitrate in aquatic systems is of fundamental importance since its presence at high levels can result in adverse effects on human health. Thus, in this work, manufactured carbon black (CB)/polylactic acid (PLA)-based 3D-printed electrochemical sensors modified with electrodeposited silver particles (AgPs) for nitrate analysis in real water samples. Raman and FT-IR spectra, scanning electron microscopy images, and analysis by energy-dispersive spectroscopy confirmed the presence of AgPs on the porous carbonaceous surface. The preliminary electrochemical studies showed that using the modified electrode (CB-PLA/AgPs) an incredible increase in the electrochemical response (around 16.5-fold in terms of current density) was obtained for the electroreduction of nitrate at around − 1.08 V vs. Ag|AgCl|KCl(sat.) compared to the unmodified electrode (CB-PLA). The linear sweep voltammetry technique was employed whose instrumental parameters have been carefully optimized. Under optimized conditions, a linear range between 5 and 80 mg L⁻¹ (R² > 0.99) was achieved, with a detection limit of 2.7 mg L⁻¹, which is below the maximum level permitted (50 mg L⁻¹) by the World Health Organization (WHO). Repeatability (intra-electrode, n = 8) and reproducibility (inter-electrode, n = 3) studies were performed, and RSDs < 2.1% were found, demonstrating good precision of the analysis and reproducible manufacturing process of the sensors. Moreover, the proposed sensor proved to be selective in the presence of other inorganic compounds frequently found in environmental waters. Importantly, in the recovery tests, percentage values between 91 and 117% confirmed the accuracy and reliability of the analyses. Thus, the developed strategy can be useful for nitrate sensing in real water samples in remote locations.
... In the past, a variety of metal materials such as Au and Se [38]; Rh, Ir, Pt, and Ag [39]; Pd; and Ni have been tested and studied for nitrate determination but, in the last years, Cu-based materials [30][31][32][33] are found to be the most efficient electro-catalysts for nitrate detection in both alkaline [40] and acidic media [41] due to their low overpotential for reduction of nitrate ions [42]. Recently, different researchers studies have reported the electrochemical detection of nitrates or nitrite molecules in water, such as PEG-SH/SePs/AuNPs poly (ethylene glycol) methylether thiol (PEG-SH) coating carbon paper electrodes with selenium particles (SePs), and gold nanoparticles (AuNPs) [38], Cu-based nanowires electrode [10], Ag/ Cu/MWNT silver and copper nanoclusters, and multiwalled carbon nanotubes electrodeposited on a glassy carbon electrode [39], ion-imprinted polymer: copper nanoparticles-polyaniline matrix on a GCE [43], modified glassy carbon sensor based on TDAN/PVC membrane [44], copper nanowire array [45], copper oxide impregnated glassy carbon spheres-basal plane pyrolytic graphite electrode (Cu x O-GCS-BPPGE) [46], modified electrode with two regions (Pt and Ag regions) by electro-deposition [47], flexible screen-printed sensors functionalized with electro-deposited copper [48], MWCNTs/PDMS sensor [49], 3D-printed copper garden electrode [50], La 2 Sn 2 O 7 /f-HNT composite for non-enzymatic detection of 3-nitro-l-tyrosine [51], and screen-printed electrode (SPE) modified with a composite consisting of Mn 3 O 4 microcubes and thin sheets of graphene oxide [52]. ...
... In the case of the LSCu sensor, the mechanism for nitrate detection is as follows [48]: ...
Nanoparticle-based materials have played an important role in the development of new electrochemical sensors and received recently tremendous attention for the detection of toxic ions such as nitrate molecules ( and ). Here, we employ La1.7Sr0.3CuO4 (LSCu) and La0.6Sr0.4Co0.8Fe0.2O3 (LSCF) low-cost, highly sensitive nanoparticles modified with black carbon as sensors for the detection of nitrate ions. The modified nanooxides were synthesized by a simple citrate method then prepared with black carbon powder and nafion solution as a sensing matrix on a glassy carbon electrode for the determination of nitrates ions in water using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy as electrochemical techniques. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for structural and morphological characterization. The calculated crystallite size d, using the Debye–Scherrer equation was found to be 325,193 nm for LSCu and 208,317 nm for LSCF by XRD technique. The grain sizes are, respectively, 47.80 nm and 65.05 nm which were extracted by SEM analysis. In this work, the modified sensors based on LSCu and LSCF demonstrate satisfactory response and sensitivities toward nitrate molecules compared with previous works. They characterized with very low detection limits of 0.0014 nM and 0.02 nM, high sensitivities of 58.8 and 57.3 µA.µM−1, respectively, and recorded a wide linear range from 1 M to 10–12 M for LSCF and 4 M to 10–13 M for LSCu.
Both of the modified electrodes demonstrated excellent results in real river water sample with low detection limits of 3.1 nM for LSCu and 3.5 nM for LSCF and very good recoveries of 100.6% and 101.65%, respectively.
