Detection Of N2H4 Research Articles

Ruthenium Nanoparticles Decorated Tungsten Oxide as a Bifunctional Catalyst for Electrocatalytic and Catalytic Applications.

The syntheses of highly stable ruthenium nanoparticles supported on tungsten oxides (Ru-WO3) bifunctional nanocomposites by means of a facial microwave-assisted route are reported. The physicochemical properties of these Ru-WO3 catalysts with varied Ru contents were characterized by a variety of analytical and spectroscopic methods such as XRD, SEM/TEM, EDX, XPS, N2 physisorption, TGA, UV-vis, and FT-IR. The Ru-WO3 nanocomposite catalysts so prepared were utilized for electrocatalytic of hydrazine (N2H4) and catalytic oxidation of diphenyl sulfide (DPS). The Ru-WO3-modified electrodes were found to show extraordinary electrochemical performances for sensitive and selective detection of N2H4 with a desirable wide linear range of 0.7-709.2 μM and a detection limit and sensitivity of 0.3625 μM and 4.357 μA μM-1 cm-2, respectively, surpassing other modified electrodes. The modified GCEs were also found to have desirable selectivity, stability, and reproducibility as N2H4 sensors, even for analyses of real samples. This is ascribed to the well-dispersed metallic Ru NPs on the WO3 support, as revealed by UV-vis and photoluminescence studies. Moreover, these Ru-WO3 bifunctional catalysts were also found to exhibit excellent catalytic activities for oxidation of DPS in the presence of H2O2 oxidant with desirable sulfoxide yields.

Facile synthesis of three-dimensional porous Au@Pt core-shell nanoflowers supported on graphene oxide for highly sensitive and selective detection of hydrazine

A novel strategy is developed to synthesize three-dimensional porous Au@Pt core-shell nanoflowers supported on GO (Au@Pt-nFs/GO) for enhanced electrochemical sensing of hydrazine (N2H4). Au@Pt-nFs/GO nanocomposite was synthesized through a facile and green method, where ascorbic acid and chitosan were employed as the reductant and linking agent, respectively. The experiment results revealed that a large numbers of Au@Pt-nFs with Au cores and Pt dendritic shells were distributed on the surface of GO sheets. Meanwhile, Au@Pt-nFs/GO with large surface area, abundant active sites and open structure reduced the overpotential and accelerated kinetics of N2H4 oxidation, therefore making the sensor based on Au@Pt-nFs/GO exhibit an excellent performance for N2H4 analysis with a wide linear range of 0.8μM–0.429mM, a high sensitivity of 1695.3μAmM−1cm−2 and a low detection limit of 0.43μM (S/N=3). Moreover, the sensor also exhibited good selectivity, repeatability and stability. Application of the sensor for the detection of N2H4 in tap water samples was demonstrated.

MnCo2S4 nanoparticle-assembled hierarchical porous sphere as an effective electrocatalyst for highly sensitive and selective nonenzymatic detection of hydrazine

It is highly attractive to design and construct a novel enzyme-free electrode for sensitive and selective detection of hydrazine (N2H4). In this paper, for the first time, porous MnCo2S4 sphere was used as an excellent electrocatalyst for N2H4 oxidation, which was synthesized through a facile hydrothermal method. The experiment results revealed that porous MnCo2S4 sphere was constructed from interconnected nanoparticle with a three-dimensional porous structure. Electrochemical measurements demonstrate that the presence of MnCo2S4 reduced the overpotential and accelerated kinetics of N2H4 oxidation. The sensor based on porous MnCo2S4 sphere exhibited an excellent performance for N2H4 analysis with a wide linear range of 0.5μM–4.78mM, a high sensitivity of 1495.7μAmM−1cm−2, a low detection limit of 0.33μM (S/N=3). Moreover, the application of the sensor for detection of N2H4 in tap water samples was demonstrated, which indicates that MnCo2S4 can be employed as the efficient material for electrochemical sensing of N2H4.

2-benzothiazoleacetonitrile based two-photon fluorescent probe for hydrazine and its bio-imaging and environmental applications

A novel turn-on two-photon fluorescent probe NS-N2H4 was developed with the 2-benzothiazoleacetonitrile as a new recognition site for the detection of hydrazine (N2H4). The two-photon probe exhibited favorable properties including high selectivity, low cytotoxicity and almost 16-fold fluorescence enhancement in the presence of N2H4 in solution. The probe could be used to image hydrazine in the living cells. Notably, we also used the two-photon fluorescent probe to image hydrazine in the tissue imaging for the first time. Furthermore, by the way of probe-loaded TLC plate, we further monitored vapor of hydrazine. Therefore, the novel two-photon probe is expected to be employed to detect N2H4 in biosamples and environmental pollution and the new recognition site will be widely applied to construct fluorescent probes for the detection of N2H4.

A highly selective long-wavelength fluorescent probe for hydrazine and its application in living cell imaging

A highly selective long-wavelength turn-on fluorescent probe has been developed for the detection of N2H4. The probe was prepared by conjugation the tricyanofuran-based D-π-A system with a recognizing moiety of acetyl group. In the presence of N2H4, the probe can be effectively hydrazinolysized and produce a turn-on fluorescent emission at 610nm as well as a large red-shift in the absorption spectrum corresponding to a color change from yellow to blue. The sensing mechanism was confirmed by HPLC, MS, UV-vis, emission spectroscopic and theoretical calculation studies. The probe displayed high selectivity and sensitivity for N2H4 with a LOD (limit of detection) of 0.16μM. Moreover, the probe was successfully utilized for the detection of hydrazine in living cells.

A Facile One-Step Synthesis of Fe2O3 Nanoparticles/Reduced Graphene Oxide for Enhanced Hydrazine Sensing

Fe2O3 nanoparticles/reduced graphene oxide (Fe2O3/rGO) nanocomposites were synthesized for enhanced electrochemical sensing of N2H4. Fe2O3/rGO nanocomposites were synthesized through a green and facile one-step hydrothermal approach by using L-lysine as both reductant and hydrolysis-controlling agent. Then, the nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), energy-dispersive X-ray spectrum (EDS), fourier transform infrared spectroscopy (FTIR) and electrochemical techniques. SEM and TEM observations revealed that large numbers of Fe2O3 nanoparticles with spherical morphologies were distributed on the surface of rGO sheets, which made the sensor based on Fe2O3/rGO exhibited an excellent performance toward N2H4 detection with a wide linear range of 0.8 μM to 1.27 mM, a high sensitivity of 525.3 μA mM−1 cm−2 and a low detection limit of 0.09 μM (S/N = 3). Therefore, the facile approach and excellent experimental results indicated that Fe2O3/rGO nanocomposites can be applied as a promising type of sensing material for electrochemical detection of N2H4.

A highly sensitive and selective fluorescent probe for N2H4 in air and living cells

A new colorimetric and fluorescent probe developed for the sensitive and selective detection of N2H4 in air and aqueous solution.

A highly selective fluorescent probe based on coumarin for the imaging of N2H4 in living cells

A turn-on fluorescence probe for highly sensitive and selective detection of N2H4 was developed based on hydrazine-triggered a substitution- cyclization-elimination cascade. Upon the treatment with N2H4, probe 1, 4-methyl-coumarin-7-yl bromobutanoate, displayed a remarkable fluorescence enhancement (25-fold) with a maximum at 450nm. This probe can quantitatively detect N2H4 with a extremely low detection limit as 7×10−8M. Moreover, cell imaging experiments have indicated that probe 1 has potential ability to detect and image N2H4 in biological systems.

Mechanism of the Electrochemical Oxidation of Ammonia over Platinum: An in Situ attenuated Total Reflection Infrared Study

The recent development of anion exchange membranes (AEMs) has increased the potential and the importance of ammonia as a fuel for anion exchange membrane fuel cells (AEMFCs). Although the reaction mechanism for the electrochemical ammonia oxidation over Pt electrode has been extensively studied, there is no report on the detection of the prospected intermediates and/or the poisoning species on Pt electrode. In this study, the electro-oxidation of ammonia over Pt electrode in alkaline aqueous solutions was studied by in situ attenuated total reflection infrared (ATR-IR) spectroscopy. In the presence of NH3, the band ascribable to the HNH bending mode of adsorbed NH3 was confirmed at 1662−1674 cm−1 in the potential range of 0.1−1.1 V. The intensity of this band decreased continuously with a rise in potential, indicating the oxidative consumption of adsorbed ammonia. In response to this behavior, the band at 1269 cm−1 appeared alternatively above 0.2 V, and its intensity reached the local maximal value at ca. 0.4 V. Note that this potential of ca. 0.4 V agreed well with the onset potential of ammonia oxidation, ca. 0.45 V, in the linear sweep voltammogram. This 1269 cm−1 band was assigned to the NH2 wagging mode of N2H4, which was one of the active intermediates, N2H x + y ,ad (x = 1 or 2, y = 1 or 2), according to the mechanism proposed by Gerischer and Mauerer. To the best of our knowledge, this is the first report for the detection of N2H4 as a reaction intermediate over Pt electrode. Furthermore, the formation of bridged NO was also observed above the onset potential of ammonia oxidation, ca. 0.5 V. Such adsorbed NO species probably inhibit the electrochemical reaction due to the occupation of reaction sites at higher potential. Figure 1

Interdigitated microelectrodes for oxygen removal in N2H4 sensors

Interdigitated micro-electrode arrays were employed to investigate the role of dissolved oxygen on direct electrochemical sensors for hydrazine. The results show that the simultaneous hydrazine oxidation and oxygen reduction result in a lower oxidation current than was expected. However, on a commercial interdigitated device, the experiments carried out demonstrate that the contribution of an interfering species at the sensing electrode may be reduced if the potential of the other electrode is set to reduce that species. For the detection of N2H4 in presence of air, this translates to an improvement of >40% in the oxidation response for hydrazine recorded during Cyclic Voltammetry (CV) in a N2H4 0.5mM solution. Further improvement was achieved by increasing the height of the set of microelectrodes dedicated to oxygen removal by Pt galvanostatic electrodeposition. The resulting oxidation response on such modified interdigitated microelectrodes was increased by almost 70%, and as much as 80% of O2 molecules was prevented to reach the sensing electrode.

In Situ Attenuated Total Reflection Infrared Spectroscopy on Electrochemical Ammonia Oxidation over Pt Electrode in Alkaline Aqueous Solutions.

The electrochemical oxidation of ammonia over Pt electrode in alkaline aqueous solutions was studied by in situ attenuated total reflection infrared (ATR-IR) spectroscopy. In 0.1 M NH3-1 M KOH, the band ascribable to the HNH bending mode of adsorbed NH3 was confirmed at 1662-1674 cm(-1) in the potential range of 0.1-1.1 V. The intensity of this band decreased continuously with a rise in potential, indicating the oxidative consumption of adsorbed ammonia. In response to this behavior, the band at 1269 cm(-1) appeared alternatively above 0.2 V, and its intensity reached the local maximal value at ca. 0.4 V. Note that this potential of ca. 0.4 V agreed well with the onset potential of ammonia oxidation, ca. 0.45 V, in the linear sweep voltammogram. This 1269 cm(-1) band was assigned to the NH2 wagging mode of N2H4, which was one of the active intermediates, N2H(x+y,ad) (x = 1 or 2, y = 1 or 2), according to the mechanism proposed by Gerischer and Mauere. To the best of our knowledge, this is the first report for the detection of N2H4 as a reaction intermediate over Pt electrode. Furthermore, the formation of bridged NO was also observed above the onset potential of ammonia oxidation, ca. 0.5 V. Such adsorbed NO species probably inhibit the electrochemical reaction due to the occupation of reaction sites at higher potential.

Morphology and chemical composition dependent synthesis and electrochemical properties of MnO2-based nanostructures for efficient hydrazine detection

In this contribution, various MnO2-based nanostructures with different morphologies and chemical compositions were prepared using a facile hydrothermal method. The structural evolution as a function of aging time from 3 to 72h was monitored. All the synthesized samples were thoroughly characterized using XRD, SEM, and FTIR, etc. The results indicated that pure α-MnO2 and Mn7O13·5H2O/α-MnO2 nanocomposite with various morphologies including nanoflowers, nanoflowers & nanorods, nanorods, nanotubes, and nanofibers can be obtained. Then, the electrochemical performance of all the prepared MnO2 based electrodes for the detection of hydrazine was investigated. Comparing to pure α-MnO2, the Mn7O13·5H2O/α-MnO2 nanocomposite was much more efficient, which showed a very high sensitivity of 109.55μAmM−1cm−2, a low detection limit of 2.06μM (S/N=3), and a wide linear range from 30μM to 2.83mM. The results revealed that both the morphology and the chemical composition of the MnO2 based electrode nanomaterials are crucial for their electrochemical properties and the Mn7O13·5H2O/α-MnO2 nanocomposite represents a novel and promising electrode material for the efficient detection of N2H4.

A flavone-based ESIPT fluorescent sensor for detection of N2H4 in aqueous solution and gas state and its imaging in living cells

A novel probe (1) based on flavone was synthesized and used for the detection of hydrazine in a mixture of phosphate buffer saline (PBS, pH 7.0, 20mM) and DMSO (1/9, vPBS/vDMSO) at room temperature. The limit of detection is 0.15μM (4.8ppb), which is lower than the U.S. Environmental Protection Agency standard (10ppb). Notably, probe 1 could be used for gas state discrimination of hydrazine with different concentrations through color changes from readily prepared strips. Additionally, probe 1 could also be applied for the imaging of hydrazine in living cells.

Rapid detection of hydrazine in a naphthol-fused chromenyl loop and its effectiveness in human lung cancer cells: tuning remarkable selectivity via the reaction altered pathway supported by theoretical studies.

Our designed and synthesized chemosensor naphthalene based chromenyl derivative (NAC) [1-(3-hydroxy-3 methyl-3H-benzo[f]chromen-2-yl) ethanone] has been used for fast (<30 s, DL = 0.22 ppb) and selective detection of N2H4 by a new way via the chromenyl ring opening followed by the pyrazole ring formation giving a strong blue fluorescence. The DFT study and the real application in different water samples along with the dipstick method in low cost devices have also been performed here. Human lung cancer cells (NCI-H460) have been used for hydrazinolysis of the NAC in vivo system for detection by the appearance of blue fluorescence and also for the MTT assay showing its remarkable cancer sensitivity.

Synergistic effect of the reducing ability and hydrogen bonds of tested gases: highly orientational CdS dendrite sensors

Semiconductor gas sensors play important roles in detecting toxic gases in various workplaces for human safety. The gas-sensing characteristics of highly orientational CdS dendrite (HOCSD) sensors were investigated. The results showed that the HOCSD sensors exhibited an excellent response and high response speed to HCOOH and N2H4, compared to HCHO and n-BuNH2. The high performance of the HOCSD sensors towards HCOOH and N2H4 detection could be attributed to two factors: the improved diffusion and adsorption/desorption ability of the CdS dendrites, and the synergistic effect of the reduction ability and hydrogen bonds of detected gases. Moreover, it is believed that the HOCSD sensors could be potentially applied to detect the HCOOH and N2H4 with high response, fast response speed and good repeatability.