Determination Of Hydrazine Research Articles

Design of high-performance electrochemical sensor based on SnS2 nanoplates and ionic liquid-modified carbon paste electrode for determination of hydrazine in water samples

Designing effective and accurate analytical techniques to determine hydrazine is essential for preserving the environment. Herein, an electrochemical sensor based on a carbon paste electrode (CPE) modified with SnS2 nanoplates (SnS2NPs) and ionic liquid (IL) was presented for determination of hydrazine in water samples. The SnS2NPs were synthesized using the hydrothermal method and characterized through field emission scanning electron microscope, Fourier transform infrared spectrometer and energy dispersive spectroscopy. The use of cyclic voltammetry in electrochemical investigations has shown that incorporating IL and SnS2NPs in an electrochemical sensor significantly improves its efficiency. These results in a considerable increase in the oxidation peak current and a decrease in the oxidation peak potential of hydrazine compared to an unmodified CPE. The method of differential pulse voltammetry was utilized to accurately measure the quantity of hydrazine. The SnS2NPs/ILCPE showed improved sensing capabilities, resulting in a noticeable sensitivity of 0.0747 µA/µM and a low limit of detection of 0.05 µM for a broad linear range of hydrazine concentration from 0.08 µM to 450.0 µM. In addition, the SnS2NPs/ILCPE sensor was successfully utilized to measure the amount of hydrazine present in water samples, with a recovery range of 96.0 to 104.4 %. The relative standard deviation was found to be lower than 3.6 % (n = 5), indicating that the developed sensor is suitable for accurately determining hydrazine in water samples with high sensitivity.

Bi-functional NiFe2O4/SrTiO3 S-scheme heterojunction for eminent performance photocatalytic treatment of sewage effluent and electrochemical hydrazine determination

Devising of materials that afforded dual applicability in decontamination and pollutant detection were still a towering challenge owing to the increasing flux of discharge toxic contaminants over the years. Herein, the NiFe2O4 nanoparticles-loaded on cube-like SrTiO3 (NiFe2O4/SrTiO3) composite was fabricated by a two-step hydrothermal approach providing remarkable photocatalytic treatment and electrochemical sensing of noxious pollutants in wastewater. The material traits of the fabricated composite were scrutinized by myriad characterization approaches. The NiFe2O4/SrTiO3 hybrid material demonstrated high surface area of 19.81 m2/g, adequate band gap energy of 2.75 eV, and prominent photoluminescence characteristics. In the presence of visible light, the NiFe2O4/SrTiO3 exhibited profound photocatalysis capability to eliminate sewage effluent-bearing chlortetracycline hydrochloride (CTCH) with 88.6% COD removal in 120 min, outperforming other pure materials. Meanwhile, the toxicity examination of effluent, the possible degradation pathway of CTCH and the proposed photocatalysis mechanism were also divulged. More importantly, the glassy carbon electrode was modified with synergized NiFe2O4/SrTiO3 (NiFe2O4/SrTiO3−GCE) was adopted for the precise quantification of Hydrazine (Hz). The NiFe2O4/SrTiO3−GCE obeyed first-order response for the Hz detection within the range of 1–10 mM: cyclic voltametric: limit of detection (LOD) of 0.119 μM with sensitivity of 18.9 μA μM−1 cm−2, and linear sweep voltametric: LOD of 0.222 μM with a sensitivity of 12.05 μA μM−1 cm−2. The stability and interference of modified electrode were also inspected. This work furnished valuable insights to yield a composite with the prominent S-scheme heterojunction system for quenching of charge carrier recombination and consequently contributing to the future realization into the domains of environmental clean-up and toxic chemical detection.

Electrocatalysis Using Cobalt Porphyrin Covalently Linked with Multi-Walled Carbon Nanotubes: Hydrazine Sensing and Hydrazine-Assisted Green Hydrogen Synthesis.

Acid-treated multi-walled carbon nanotube (MWCNT) covalently functionalized with cobalt triphenothiazine porphyrin (CoTriPTZ-OH) A3B type porphyrin, containing three phenothiazine moieties (represented as MWCNT-CoTriPTZ) is synthesized and characterized by various spectroscopic and microscopic techniques. The nanoconjugate, MWCNT-CoTriPTZ, exhibits a pair of distinct redox peaks due to the Co2+/Co3+ redox process in 0.1M pH 7.0 phosphate buffer. Further, it electrocatalytically oxidizes hydrazine at a low overpotential with a high current. This property is advantageously utilized for the sensitive determination of hydrazine. The developed electrochemical sensor exhibits high sensitivity (0.99 µAµM-1cm-2), a low limit of detection (4.5 ppb), and a broad linear calibration range (0.1µM to 3.0mM) for the determination of hydrazine. Further, MWCNT-CoTriPTZ is exploited for hydrazine-assisted green hydrogen synthesis. The high efficiency of hydrazine oxidation is confirmed by the low onset potential (0.45V (vs RHE)) and 0.60V (vs RHE) at the current density of 10mA.cm-2. MWCNT-CoTriPTZ displays a high current density (77.29mA.cm-2) at 1.45V (vs RHE).

Ti3AlC2 MAX Phase Modified Screen-Printed Electrode for the Fabrication of Hydrazine Sensor.

Hydrazine is considered a powerful reducing agent and catalyst, showing diverse applications in agricultural industries, toxic degradation research, and wastewater management. Additionally, hydrazine can trigger some specific reactions when combined with suitable oxidants. Due to its highly polar nature, hydrazine can easily dissolve in alcohol, water, and various other polar solvents. Therefore, it can be extensively utilized in different areas of application and industries such as rocketry and various chemical applications. Despite its beneficial properties, hydrazine is unstable, posing significant risk due to its highly toxic nature. It is extremely hazardous to both human health and the environment. It can cause various illnesses and symptoms such as dizziness, temporary blindness, damage to the central nervous system, and even death when inhaled in sufficient quantities. Therefore, it is highly important to monitor the level of hydrazine to prevent its toxic and hazardous effects on human beings and the environment. In the present study, we discuss the simple fabrication of a disposable cost-effective and eco-friendly hydrazine sensor. We used a screen-printed carbon electrode, i.e., SPCE, as a base for the construction of a hydrazine sensor. The Ti3AlC2 MAX has been used as a suitable and efficient electrode material for the fabrication of disposable hydrazine sensors. We modified the active surface of the SPCE using a drop-casting approach. The resulting Ti3AlC2 MAX modified SPCE (Ti3AlC2@SPCE) has been utilized as an efficient and low-cost hydrazine sensor. Cyclic voltammetry, i.e., CV, and linear sweep voltammetry, viz., LSV, was employed as a sensing technique in this study. The optimization of pH and electrode material loading was conducted. The Ti3AlC2@SPCE exhibited excellent sensing performance toward hydrazine oxidation. A reasonable detection limit (0.01 µM) was achieved for hydrazine sensing. The fabricated sensor also demonstrated a reasonable linear range of 1-50 µM. This work provides the design and fabrication of simple disposable Ti3AlC2@SPCE as a suitable electrode for the determination of hydrazine using LSV technology.

Exploring alkyl-diamine chain length effects on electrochemical behavior of AuNPs fabricated electrodes: Influence of linkers on the sensitive detection of hydrazine

In this electrochemical exploration, we scrutinized the influence of alkyl-diamine (AD) chain length as crucial linkers between glassy carbon electrodes (GCE) and citrate-capped gold nanoparticles (Cit-AuNPs), focusing on their conductive behavior and sensing proficiency, particularly in hydrazine detection. Meticulous examination of self-assembled monolayers (SAMs) formed by three distinct ADs, namely 1,6-hexanediamine (HDA), 1,8-octanediamine (ODA) and 1,10-decanediamine (DDA) unfolded over GC surfaces revealed a precise adherence to Langmuir adsorption kinetics during the SAM formation process. Utilizing cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), the electrochemical activity of the [Ru(NH₃)₆]³⁺/²⁺ redox pair at electrodes modified with ADs was investigated. The proposed mechanism involves a Michael-like nucleophilic addition process at the GC surface/diamine solution interface during the SAM formation. Analysis across various techniques underscored the compact nature of the DDA-formed SAM in comparison to HDA and ODA. Exploiting the free amine functional groups on the SAMs, the as-synthesized Cit-AuNPs were attached on the electrode surface and investigated comprehensively through CV, EIS, attenuated total reflection Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. Remarkably, Cit-AuNPs attached DDA-SAM/GC electrode offered superior electro active surface area, establishing an advanced electrochemical platform for carcinogenic hydrazine determination. The DDA/Cit-AuNPs electrode demonstrated a linear determination range of 0.003–1 mM, limits of detection at 11 nM, and sensitivity of 1080 µA mM−1 cm−2. This study gives a complete picture of how AD chain lengths, SAM formation, Cit-AuNPs attachment, and electrocatalytic performance work together to make an advanced electrochemical sensing scaffold for environmental pollutants determination.

Selective Amperometric Sensor for the Determination of Hydrazine at a Gold Nanoparticle Decorated Poly(Brilliant Blue) Modified Electrode

There is a pressing requirement to synthesize stable electrode components that possess enhanced capabilities for creating electrochemical sensors, which are sensitive and discerning, to swiftly detect dangerous noxious substances. A sensitive electrochemical sensor has been developed in this study for hydrazine (HY) oxidation, utilizing gold nanoparticles (AuNPs) and poly(brilliant blue) (p(BB)) modifiers on the surface of the pencil graphite electrode (PGE). The features of the sensor for detecting hydrazine were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Additionally, when examined under optimal parameters using CV and amperometry, the proposed hydrazine sensor presents favorable electrochemical and analytical figures of merit. The AuNPs/p(BB)/PGE provides the determination of low levels of hydrazine in water samples with a detection limit of 0.14 µM. A wide linear range from 1.0 to 800 μM was obtained. The findings indicate that the AuNPs/p(BB)/PGE sensor exhibits good stability, repeatability, and reproducibility for hydrazine. The proposed sensor was effectively used to determine hydrazine in both water and mineral water samples.

Synthesis of ZnO@TiO2 nanoparticles and its application to construct an electrochemical sensor for determination of hydrazine

In the present research, ZnO@TiO2 nanoparticles (ZnO@TiO2 NPs) was synthesized by using a simple method and the results of infrared (IR), X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and energy-dispersive X-ray spectroscopy (EDX) confirmed their synthesis. Then, an electrochemical sensor based on screen printed graphite electrode (SPGE) modified with ZnO@TiO2 NPs was developed for voltammetric detection of hydrazine in water samples. The ZnO@TiO2 NPs modified SPGE demonstrates significant performance toward the hydrazine detection due to the synergistic effect between ZnO NPs and TiO2 NPs and it proved by the results from cyclic voltammetry (CV). Also, the observation of an oxidation peak without a reduction peak in the opposite scan direction indicated the irreversibility of the electrochemical oxidation of hydrazine on both the bare SPGE and the ZnO@TiO2/SPGE. Under optimized conditions (pH and differential pulse parameters), the voltammetric current response of hydrazine at the ZnO@TiO2/SPGE showed linear dependence on the concentration, ranging from 0.01 µM to 585.0 µM with a limit of detection (LOD) of 0.005 µM. In addition, the pertinency of the ZnO@TiO2/SPGE sensor for practical applications was investigated by quantification detection of hydrazine in water samples. The findings showed recovery values between 97.3 % and 104.2 % and relative standard deviations (RSDs) ≤ 3.5 % for river and tap water samples.

Organotrialkoxysilanes Mediate the Syntheses of Fluorescent Gold Nanoparticles and TiO2‐Supported Ag−Ni Nanocatalysts for Selective Hydrazine Sensing and Decomposition

AbstractOrganotrialkoxysilanes enabled the controlled synthesis of mono‐metallic and bimetallic noble metal nanoparticles. 3‐Aminopropyltrimethoxysilane (3‐APTMS)‐treated gold cations were quickly (1 minute) transformed into gold nanoparticles (AuNPs) in the presence of 3‐glycidoxypropyltrimethoxysilane (3‐GPTMS). As made AuNPs demonstrated exceptional fluorescence properties with 15 % QY, and the blue fluorescence of nanomaterials is supported by CIE coordinates. Fluorescent gold nanoparticles were evaluated using UV‐ Visible spectroscopy, X‐ray photoelectron spectroscopy (XPS), zeta potential, X‐ray diffraction (XRD), fluorescence spectroscopy (FL), and transmission electron microscopy (TEM), mediated by the use of organotrialkoxysilanes, gold nanoparticles with an average particle size of 4–8 nm were produced, which could be helpful for the direct determination of hydrazine via fluorescence spectroscopy. The detection limit for hydrous hydrazine is 0.047 μM, with a linear range of 0.1–1 μM (R2=0.995). In addition, organotrialkoxysilanes were also used as templates for the stabilization and formation of supported TiO2 bimetallic Ag−Ni nanoparticles for use as photo‐nanocatalysts. TiO2‐supported bimetallic Ag−Ni nanocatalyst were characterized by field emission scanning electron microscope (FE SEM), EDX, elemental mapping, and the Brunauer‐Emmett‐Teller (BET) technique. Real‐time hydrazine decomposition was enabled by the as‐built heterogeneous support in the presence of sunlight.

Lignosulfonate-Assisted In Situ Deposition of Palladium Nanoparticles on Carbon Nanotubes for the Electrocatalytic Sensing of Hydrazine.

This paper presents a novel modified electrode for an amperometric hydrazine sensor based on multi-walled carbon nanotubes (MWCNTs) modified with lignosulfonate (LS) and decorated with palladium nanoparticles (NPds). The MWCNT/LS/NPd hybrid was characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The electrochemical properties of the electrode material were evaluated using cyclic voltammetry and chronoamperometry. The results showed that GC/MWCNT/LS/NPd possesses potent electrocatalytic properties towards the electro-oxidation of hydrazine. The electrode demonstrated exceptional electrocatalytic activity coupled with a considerable sensitivity of 0.166 μA μM-1 cm-2. The response was linear from 3.0 to 100 µM L-1 and 100 to 10,000 µM L-1, and the LOD was quantified to 0.80 µM L-1. The efficacy of the modified electrode as an electrochemical sensor was corroborated in a study of hydrazine determination in water samples.

Supramolecular phenolic network-engineered C–CeO2 nanofibers for simultaneous determination of isoniazid and hydrazine in biological fluids

Electrochemical sensing provides a powerful technological means for the therapeutic drug monitoring of drug-resistant tuberculosis but requires a functionalized electrode to capture the analytes and catalyze their redox reactions. Herein, we construct a nickel–tannic acid supramolecular network (Ni–TA) on the surface of electrospun-derived C–CeO2 nanofiber for the sensitive and simultaneous detection of isoniazid (INZ) and hydrazine (HYD). Mechanistic investigations demonstrate that Ni–TA is electronegative and hydrophilic, thus facilitating an efficient mass and electron transfer. Ni–TA/C–CeO2 has higher adsorption rate constants (0.091 g mg–1 h–1 for INZ, and 0.062 g mg–1 h–1 for HYD) than native C–CeO2 (0.075 g mg–1 h–1 for INZ, and 0.047 g mg–1 h–1 for HYD). Moreover, Ni–TA/C–CeO2 (56 Ω) has lower charge transfer resistances than C–CeO2 (417 Ω). Ni–TA/C–CeO2 performs low detection limits and wide linearity ranges for INZ (0.012 µmol/L and 0.1–400 µmol/L, respectively) and HYD (0.008 µmol/L and 0.015–1420 µmol/L, respectively), coupled with high selectivity, cycle stability and reproducibility. This research demonstrated the promising applications of Ni–TA/C–CeO2 by analyzing human-collected plasma and urine samples.

Cinnamyl Chalcone Based AIE Fluorescent Probes for Sensitive Detection of Hydrazine and its Application in Living Cells.

Widely utilized in the chemical industry and agriculture, hydrazine is easily absorbed by living things and can cause physical harm when in touch for an extended period of time. As a result, a novel cinnamaldehyde chalcone C5 was produced by Friedel Crafts process and aldol condensation reaction. Triphenylamine was used as the raw material for hydrazine determination in both reactions. Chalcone C5 exhibits significant AIE behavior in a mixed mixture of ethanol and water in addition to having great selectivity and a low detection limit (0.119nm) for hydrazine. The solvent effect test revealed a linear relationship between the Stokes shift of C5 in the solvent and the rise in solvent orientation polarization. It is important to note that C5 is not harmful to MCF-7 cells, mouse kidney cells, or pig kidney cells. Furthermore, research on cell imaging has demonstrated that probe C5 may be utilized to image the fluorescence of hydrazine in active MCF-7 cells.

Amperometric Determination of Hydrazine Using Au Nanoparticle Incorporated CMK-3 Modified Glassy Carbon Electrode

Abstract In this work, ordered mesoporous carbon (CMK-3) was synthesized using nano-casting method, in which Au nanoparticles were incorporated using citrate-reduction method. It was characterized using various physicochemical techniques like XRD, Raman, HRSEM, BET, and HRTEM. The synthesized material was utilized as an electrocatalyst for the electrochemical determination of hydrazine (HZ). From the cyclic voltametric studies, it is understood that the bare as well as CMK-3 modified glassy carbon electrodes fail to produce signal against hydrazine. On the contrary, Au nanoparticle incorporated CMK-3 modified glassy carbon electrode (AuNP-CMK-3/GCE) senses the analyte at the applied overpotential of 0.22 V. Using the amperometric measurements, it is concluded that the electrode is able to produce signal against the target analyte in the concentration range of 3 – 27 µM with the R2 value of 0.9964. Further, sensitivity and limit of detection (LOD) of the electrode against HZ were found as 0.00289 µA/µM and 1 µM, respectively. The selectivity of the electrode was examined in the presence of other interferrents, which revealed that the electrode is selective to HZ. The real-time applicability of the electrode was ascertained in the water samples collected from pond and water fountain.

Enhanced electrocatalytic activity of fluorine doped tin oxide (FTO) by trimetallic spinel ZnMnFeO4/CoMnFeO4 nanoparticles as a hydrazine electrochemical sensor

In the present study, ZnMnFeO4 and CoMnFeO4 tri-metallic spinel oxide nanoparticles (NPs) were provided using hydrothermal methods. The nanoparticles have been characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and electrochemical techniques. A reliable and reproducible electrochemical sensor based on ZnMnFeO4/CoMnFeO4/FTO was fabricated for rapid detection and highly sensitive determination of hydrazine by the DPV technique. It is observed that the modified electrode causes a sharp growth in the oxidation peak current and a decrease in the potential for oxidation, contrary to the bare electrode. The cyclic voltammetry technique showed that there is high electrocatalytic activity and excellent sensitivity in the suggested sensor for hydrazine oxidation. Under optimal experimental conditions, the DPV method was used for constructing the calibration curve, and a linear range of 1.23 × 10−6 M to 1.8 × 10−4 M with a limit of detection of 0.82 ± 0.09 μM was obtained. The obtained results indicate that ZnMnFeO4/CoMnFeO4/FTO nano sensors exhibit pleasant stability, reproducibility, and repeatability in hydrazine measurements. In addition, the suggested sensor was efficiently employed to ascertain the hydrazine in diverse samples of cigarette tobacco.

Synergistic Effects of Nanoporous Structure of Glassy Carbon Electrode and Electropolymerization of Catechol Film on the Electrocatalytic Oxidation of Hydrazine

Non-precious metal-free electrocatalysts with high sensitivity, selectivity, and long-term stability, as well as extraordinary activity towards hydrazine (HZ) oxidation are challenging and desirable for various fields. Herein, a binder-free catechol (CC)-immobilized nanoporous GCE was conducted to electrooxidation of HZ at extremely low overpotential with fast response time (∼3 s). Owing to synergistic-assisted signal amplification between the CC and nanoporous GCE, and nanoporous GCE’s high-effective-surface-area for incorporation of CC within the pores of nanoporous structure, high sensitive detection of HZ along with long-term stability has been introduced. Moreover, binder-free modification resulting in increased accessibility of the HZ to active surface sites of the electrode, which in turn increased the electrode performance. The affecting factors on the anodic signal for determination of hydrazine were optimized by response surface methodology. An optimized limit of detection of 0.14 μM was obtained at a signal to noise ratio of 3 and a fast response time (∼3 s). Additionally, CC/GCE-red revealed higher sensitivity with two linear ranges from 0.3 to 8.6 and 8.6 to 120 μM. The suggested sensor’s promising qualities include its ease of manufacture and good stability of the modified electrode.

Determination of hydrazine in air by liquid chromatography/tandem mass spectrometry combined with precolumn derivatization.

In this study, we developed a determination method for hydrazine in the air. Hydrazine was derivatized with p-dimethyl amino benzaldehyde (DBA) to yield p-dimethylaminobenzalazine, which was subjected to liquid chromatography-electrospray tandem mass spectrometry (LC/MS/MS) analysis. The derivative exhibited good sensitivity in the LC/MS/MS analysis, and its instrument detection limit and instrument quantification limit were 0.003 and 0.008ng/mL, respectively. The air sample was collected using an air sampler equipped with a peristaltic pump at 0.2L/min for 8h. We demonstrated that a silica cartridge impregnated with DBA and 1,2-bis(4-pyridyl) ethylene can collect hydrazine in the air stably. The mean recovery rates in outdoor and indoor locations were 97.6% and 92.4%, respectively. Further, the method detection and quantification limits were 0.1 and 0.4ng/m3, respectively. The proposed method does not require any pretreatment and/or concentration step, enabling high-throughput analyses.

Synthesis of MoS2-QDs@Fe3O4 nanocomposites decorated on reduced-graphene-oxide: Application in sensitive electrocatalytic determination of hydrazine

In the present work, a novel sensitive sensor for hydrazine determination was introduced based on modifying a glassy carbon electrode with MoS2-QDs@Fe3O4/rGO nanocomposite. The synthesized MoS2-QDs@Fe3O4/rGO nanocomposite was analyzed by field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), FT-IR, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), vibrating-sample magnetometry (VSM), and Brunauer–Emmett–Teller (BET) technique. The proposed structure was confirmed by the above techniques. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry techniques were used for electrochemical investigations. The effective surface area of the modified electrode and the diffusion coefficient of hydrazine were obtained as 0.1213 cm2 and 4.42 × 10−6 cm2s−1, respectively. Finally, by using the DPV technique, was recorded the calibration curve for hydrazine. Under the optimized conditions, a linear range of 0.8–2190 µM, a limit of detection of 0.12 µM, Limit of Quantitation of 0.4 µM, and sensitivity of 0.0353μAμM−1 were obtained for hydrazine through the DPV technique using the proposed sensor.

Cobalt hexacyanoferrate adsorbed on TiO2 nanoparticles and their modified glassy carbon electrodes for electrocatalytic oxidation and amperometric determination of hydrazine.

TiO2 nanoparticles (NPs) were prepared at low temperature by stepwise hydrolysis of TiF4 in aqueous solution at 100°C. TiO2 NPs were obtained at low temperature as small size particles. Subsequently, cobalt hexacyanoferrate (CoHCF) is adsorbed on the surface of the TiO2 NPs through the ion exchange method. This method is simple and forms TiO2/CoHCF nanocomposite. TiO2 interacts with KCo[Fe(CN)6] which leads to the formation of TiO(OH)-Co bond; this is confirmed by a shift in the XPS analysis. The prepared TiO2/CoHCF nanocomposite has been characterized by FT-IR spectrum, X-ray photoelectron spectra (XPS), scanning electron microscope (SEM), high resolution transmittance electron microscope (HRTEM) and energy dispersive X-ray pattern (EDX). The TiO2/CoHCF nanocomposite is modified by the glassy carbon electrode (GCE) as an excellent electrocatalyst for the oxidation of hydrazine and is also used for the amperometric determination of hydrazine.

Facile Gram-Scale Synthesis of NiO Nanoflowers for Highly Selective and Sensitive Electrocatalytic Detection of Hydrazine.

The design and development of efficient and electrocatalytic sensitive nickel oxide nanomaterials have attracted attention as they are considered cost-effective, stable, and abundant electrocatalytic sensors. However, although innumerable electrocatalysts have been reported, their large-scale production with the same activity and sensitivity remains challenging. In this study, we report a simple protocol for the gram-scale synthesis of uniform NiO nanoflowers (approximately 1.75 g) via a hydrothermal method for highly selective and sensitive electrocatalytic detection of hydrazine. The resultant material was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. For the production of the modified electrode, NiO nanoflowers were dispersed in Nafion and drop-cast onto the surface of a glassy carbon electrode (NiO NF/GCE). By cyclic voltammetry, it was possible to observe the excellent performance of the modified electrode toward hydrazine oxidation in alkaline media, providing an oxidation overpotential of only +0.08 V vs Ag/AgCl. In these conditions, the peak current response increased linearly with hydrazine concentration ranging from 0.99 to 98.13 μmol L-1. The electrocatalytic sensor showed a high sensitivity value of 0.10866 μA L μmol-1. The limits of detection and quantification were 0.026 and 0.0898 μmol L-1, respectively. Considering these results, NiO nanoflowers can be regarded as promising surfaces for the electrochemical determination of hydrazine, providing interesting features to explore in the electrocatalytic sensor field.

Differential Pulse Voltammetric Analysis of Hydrazine in Water Samples by Using Screen-Printed Graphite Electrode Modified with Nitrogen-Doped Hollow Carbon Spheres

The present study introduces a facile and efficient voltammetric hydrazine sensor via the modification of screen-printed graphite electrode (SPGE) with nitrogen-doped hollow carbon spheres (N-HCSs). This work is the first report of the new method of electroanalytical determination of hydrazine through N-HCSs modified SPGE. The N-HCSs fabricated through the templating approach (hard template) were characterized by Fourier transform infrared (FT-IR) spectroscopy, field emission-scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS). Cyclic voltammetry (CV), chronoamperometry (CA), and differential pulse voltammetry (DPV) were employed for electrochemical determinations. The produced N-HCSs/SPGE had an appreciable electrocatalytic capacity for the hydrazine oxidation, with the least oxidation overpotential and elevated voltammetric peak currents. The peak current of hydrazine oxidation on N-HCSs/SPGE possessed a distinct linear association with its levels (0.02–380.0 μM) under the optimized experimental circumstances, with the limit of detection (LOD) as narrow as 0.007 μM. Good stability and acceptable reproducibility were also attained on the N-HCSs/SPGE. In addition, the developed technique exhibited good selectivity toward the detection of hydrazine in the presence of some interfering species. The practical applicability of proposed sensor was successful by sensing hydrazine in water samples.

Benchmarking electrodes modified with bi-doped polypyrrole for sensing applications

Polypyrrole-modified electrodes bi-doped with salicylate and perchlorate anions were synthetized, characterized, and benchmarked according to their ability to meet a set of performance criteria, with the aim of obtaining the best potential candidate for the development of electrochemical sensors. Bi-doped PPy films (PPy-DA) were assessed as compared to those resulting from electropolymerization in solutions providing a single doping anion, namely salicylate (PPy-Sa) or perchlorate (PPy-ClO4−) solutions. Morphological and spectroscopic characteristics of the different polymer films were determined by means of SEM and XPS and Raman spectroscopies. The electrochemical response and electrocatalytic activity of PPy-DA electrodes were characterized by chronoamperometric, voltammetric and electrochemical impedance spectroscopy (EIS) measurements. EIS appeared as a singular tool for determining the conditions where electrochemical response is either dictated by the redox process of the polymer film or governed by a redox couple in solution, and for comparing the electrocatalytic activity of the films without the requirement of knowing the real active electrode area. Comparison was also made among PPy-DA films synthesized by varying dopant concentration in the polymerization bath and electropolymerization time. The presence of salicylate ions favored the formation of films with a three-dimensional tubular structure whereas perchlorate ions contribute to increase their conductivity and electrocatalytic activity. The tubular three-dimensional structure of the electrode surface exhibits an open extended-area pattern that is highly suitable for the electrodeposition of gold nanoparticles (AuNPs), offering new possibilities for developing electrodes for voltammetric sensing. Accordingly, electrodes modified with PPy-DA films decorated with AuNPs were successfully tested for hydrazine determination.