A sensitive and selective nitrite sensor based on a glassy carbon electrode modified with gold nanoparticles and sulfonated graphene

A graphene-printed paper electrode for determination of H2O2 in municipal wastewater during the COVID-19 pandemic

Graphene prepared through exfoliation process was printed on paper substrate using inkjet-printer and then printed paper electrode was used as an electrochemical sensor for analysis of H2O2 in cyclic voltammetry.

Au@Carbon quantum Dots-MXene nanocomposite as an electrochemical sensor for sensitive detection of nitrite

A highly sensitive electrochemical sensor was developed through a one-pot green synthesis method for nitrite detection based on the electrochemical technique. Xylan-based carbon quantum dots (CQDs) were used as green in situ reducing agent to prepare CQDs capped gold nanoparticles (Au@CQDs). MXene of good electrical conductivity was used as the immobilized matrix to fabricate Au@CQDs-MXene nanocomposites with the advantages of good electrical conductivity and electrocatalysis. An electrochemical sensor for nitrite monitor was obtained by loading the Au@CQDs-MXene on a glassy carbon electrode. The sensor presents high sensitivity, good stability, wide linear range, and excellent selectivity due to the high catalytic activity of AuNPs and CQDs, the large specific surface area of MXene, and exceptional electrical conductivity of AuNPs and MXene. Under the optimal condition, the linear detection range of the sensor was from 1 μM to 3200 μM with a detection limit of 0.078 μM (S/N = 3), which was superior to most reported sensors using differential pulse voltammetry (DPV) method. Furthermore, this sensor was successfully applied to detect nitrite in tap water and salted vegetables with satisfactory recoveries. This modified electrocatalytic sensor shows a new pathway to fabricate nitrite detection sensor with feasibility for practical application.

Recent Advancement of the Sensors for Monitoring the Water Quality Parameters in Smart Fisheries Farming

Water quality is the most critical factor affecting fish health and performance in aquaculture production systems. Fish life is mostly dependent on the water fishes live in for all their needs. Therefore, it is essential to have a clear understanding of the water quality requirements of the fish. This research discusses the critical water parameters (temperature, pH, nitrate, phosphate, calcium, magnesium, and dissolved oxygen (DO)) for fisheries and reviews the existing sensors to detect those parameters. Moreover, this paper proposes a prospective solution for smart fisheries that will help to monitor water quality factors, make decisions based on the collected data, and adapt more quickly to changing conditions.

Application of Graphene-Based Materials for Detection of Nitrate and Nitrite in Water-A Review

Nitrite and nitrate are widely found in various water environments but the potential toxicity of nitrite and nitrate poses a great threat to human health. Recently, many methods have been developed to detect nitrate and nitrite in water. One of them is to use graphene-based materials. Graphene is a two-dimensional carbon nano-material with sp² hybrid orbital, which has a large surface area and excellent conductivity and electron transfer ability. It is widely used for modifying electrodes for electrochemical sensors. Graphene based electrochemical sensors have the advantages of being low cost, effective and efficient for nitrite and nitrate detection. This paper reviews the application of graphene-based nanomaterials for electrochemical detection of nitrate and nitrite in water. The properties and advantages of the electrodes were modified by graphene, graphene oxide and reduced graphene oxide nanocomposite in the development of nitrite sensors are discussed in detail. Based on the review, the paper summarizes the working conditions and performance of different sensors, including working potential, pH, detection range, detection limit, sensitivity, reproducibility, repeatability and long-term stability. Furthermore, the challenges and suggestions for future research on the application of graphene-based nanocomposite electrochemical sensors for nitrite detection are also highlighted.

Facile synthesis and characterization of erbium oxide (Er2O3) nanospheres embellished on reduced graphene oxide nanomatrix for trace-level detection of a hazardous pollutant causing Methemoglobinaemia

The nanomaterials have received enormous attention in the catalysis applications. Particularly, we have focused on the fabrication of nanocomposite for an electrochemical sensor with improved electrocatalytic performance. Herein, a rapid and sensitive electrochemical detection of nitrite is essential for assessing the risks facing ecosystems in environment. We report a simple and robust ultrasonic-assisted synthetical route via prepared Er₂O₃ nanoparticles decorated reduced graphene oxide nanocomposite (Er₂O₃ NPs@RGO) modified electrode for nitrite detection. The composition and morphological formation were characterized by XRD, XPS, FESEM, and HRTEM. The amperometric (i-t) and cyclic voltammetry were exhibits tremendous electrocatalytic capability and superior performance toward nitrite oxidation. A sensitive and reproducible amperometric nitrite sensor was fabricated which able to detect trace concentration as 3.69 nM and excellent sensitivity (24.17 µA µM^-1 cm^-2). The method worked well even in cured meat and water samples and the results has indicates the reliability of the method in real-time analysis.

Au nanoparticles supported on functionalized two-dimensional titanium carbide for the sensitive detection of nitrite

A novel electrochemical sensing platform based on a Au NPs/Ti₃C₂T_X composite was constructed.

Electrochemical Determination of Nitrite by Au Nanoparticle/Graphene-Chitosan Modified Electrode

A highly sensitive nitrite (NO₂⁻) electrochemical sensor is fabricated using glassy carbon electrode modified with Au nanoparticle and grapheme oxide. Briefly, this electrochemical sensor was prepared by drop-coating graphene oxide-chitosan mixed film on the surface of the electrode and then electrodepositing a layer of Au nanoparticle using cyclic voltammetry. The electrochemical behavior of NO₂⁻ on the sensor was investigated by cyclic voltammetry and amperometric i-t curve. The results showed that the sensor exhibited better electrocatalytic activity for NO₂⁻ in 0.1 mol/L phosphate buffer solution (PBS) (pH 5.0). The oxidation peak current was positively correlated with NO₂⁻ concentration in the ranges of 0.9 µM to 18.9 µM. The detection limit was estimated to be 0.3 µM. In addition, the interference of some common ions (e.g., NO₃⁻, CO₃²⁻, SO₄²⁻, Cl⁻, Ca²⁺ and Mg²⁺) and oxidizable compound including sodium sulfite and ascorbic acid in the detection of nitrite was also studied. The results show that this sensor is more sensitive and selective to NO₂⁻. Therefore, this electrochemical sensor provided an effective tool for the detection of NO₂⁻.

Non-enzymatic sensors based on a glassy carbon electrode modified with Au nanoparticles/polyaniline/SnO2 fibrous nanocomposites for nitrite sensing

A non-enzymatic sensor based on Au nanoparticles (AuNPs)/polyaniline (PANI)/tin oxide (SnO₂) nanocomposites (Au/PANI/SnO₂) was prepared for enhanced electrochemical sensing of nitrite (NO₂⁻).

Electrochemical synthesis of gold nanoparticles decorated flower-like graphene for high sensitivity detection of nitrite

In this paper, the spherical Au nanoparticles and 3D flower-like structure graphene were successively deposited on glassy carbon electrode (GCE) (Au/f-GE/GCE) via a facile and two-step electrodeposition method for the detection of nitrite ions (NaNO₂). The morphology and composition elements were confirmed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction measurements (XRD). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to evaluate the electrochemical behaviors of NaNO₂ on the as-prepared electrode. Compared to f-GE/GCE and Au/GCE, Au/f-GE/GCE showed a sharp and obvious oxidation peak at 0.78V. The oxidation peak current of NaNO₂ was linearly proportional to its concentration in the range from 0.125 to 20375.98μM, with a detection limit of 0.01μM (at S/N=3). Furthermore, the experiment results also showed that the as-prepared electrode exhibited excellent reproducibility and long-term stability, as well as good recovery when applied to the determination of NaNO₂ in pickled pork samples.

Electrochemical Grafting of Graphene Nano Platelets with Aryl Diazonium Salts

To vary interfacial properties, electrochemical grafting of graphene nano platelets (GNP) with 3,5-dichlorophenyl diazonium tetrafluoroborate (aryl-Cl) and 4-nitrobenzene diazonium tetrafluoroborate (aryl-NO₂) was realized in a potentiodynamic mode. The covalently bonded aryl layers on GNP were characterized using atomic force microscopy and X-ray photoelectron spectroscopy. Electrochemical conversion of aryl-NO₂ into aryl-NH₂ was conducted. The voltammetric and impedance behavior of negatively and positively charged redox probes (Fe(CN)₆^3-/4- and Ru(NH₃)₆^2+/3+) on three kinds of aryl layers grafted on GNP reveal that their interfacial properties are determined by the charge states of redox probes and reactive terminal groups (-Cl, -NO₂, -NH₂) in aryl layers. On aryl-Cl and aryl-NH₂ garted GNP, selective and sensitive monitoring of positively charged lead ions as well as negatively charged nitrite and sulfite ions was achieved, respectively. Such a grafting procedure is thus a perfect way to design and control interfacial properties of graphene.

Preparation of hexagonal BN whiskers synthesized at low temperature and their application in fabricating an electrochemical nitrite sensor

Hexagonal boron nitride (h-BN) whiskers were synthesized via the polymeric precursor method using boric acid (H₃BO₃) and melamine (C₃H₆N₆) as raw materials at 1073–1273 K in flowing nitrogen/hydrogen (5% hydrogen).

Synthesis of Au nanoparticles dispersed on halloysite nanotubes–reduced graphene oxide nanosheets and their application for electrochemical sensing of nitrites

Electrochemical sensing of nitrite based on a novel Au–HNTs–GO nanocomposite.

A non-covalent interaction of Schiff base copper alanine complex with green synthesized reduced graphene oxide for highly selective electrochemical detection of nitrite

A novel and selective nitrite sensor based on non-covalent interaction of Schiff base copper complex [Cu(sal-ala)(phen)] with reduced graphene oxide (RGO) was developed by simple eco-friendly approach.

Electrochemical immunosensor assay (EIA) for sensitive detection of E. coli O157:H7 with signal amplification on a SG–PEDOT–AuNPs electrode interface

The SG–PEDOT–AuNPs composites not only enhance interface electron transfer efficiency, but also offer a multivalent recognition interface for conjugating E. coli.

A facile fabrication of copper particle-decorated novel graphene flower composites for enhanced detecting of nitrite

A novel 3D porous flower-like reduced graphene oxide (f-RGO) was explored as the support material for the Cu particles on glassy carbon electrode (Cu/f-RGO/GCE) for detecting nitrite.

Heteroatom-enriched and renewable banana-stem-derived porous carbon for the electrochemical determination of nitrite in various water samples

For the first time, high-surface-area (approximately 1465 m² g⁻¹), highly porous and heteroatom-enriched activated carbon (HAC) was prepared from banana stems (Musa paradisiaca, Family: Musaceae) at different carbonization temperatures of 700, 800 and 900°C (HAC) using a simple and eco-friendly method. The amounts of carbon, hydrogen, nitrogen and sulfur in the HAC are 61.12, 2.567, 0.4315, and 0.349%, respectively. Using X-ray diffraction (XRD), CHNS elemental analysis, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, the prepared activated carbon appears amorphous and disordered in nature. Here, we used HAC for an electrochemical application of nitrite (NO₂⁻) sensor to control the environmental pollution. In addition, HAC exhibits noteworthy performance for the highly sensitive determination of nitrite. The limit of detection (LODs) of the nitrite sensor at HAC-modified GCE is 0.07 μM. In addition, the proposed method was applied to determine nitrite in various water samples with acceptable results.

Computer-assisted electrochemical fabrication of a highly selective and sensitive amperometric nitrite sensor based on surface decoration of electrochemically reduced graphene oxide nanosheets with CoNi bimetallic alloy nanoparticles

For the first time, a novel, robust and very attractive statistical experimental design (ED) using minimum-run equireplicated resolution IV factorial design (Min-Run Res IV FD) coupled with face centered central composite design (FCCCD) and Derringer's desirability function (DF) was developed to fabricate a highly selective and sensitive amperometric nitrite sensor based on electrodeposition of CoNi bimetallic alloy nanoparticles (NPs) on electrochemically reduced graphene oxide (ERGO) nanosheets. The modifications were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), energy dispersive X-ray spectroscopic (EDS), scanning electron microscopy (SEM) techniques. The CoNi bimetallic alloy NPs were characterized using digital image processing (DIP) for particle counting (density estimation) and average diameter measurement. Under the identified optimal conditions, the novel sensor detects nitrite in concentration ranges of 0.1-30.0 μM and 30.0-330.0 μM with a limit of detection (LOD) of 0.05 μM. This sensor selectively detects nitrite even in the presence of high concentration of common ions and biological interferents therefore, we found that the sensor is highly selective. The sensor also demonstrated an excellent operational stability and good antifouling properties. The proposed sensor was used to the determination of nitrite in several foodstuff and water samples.