Showing papers on "Hydrazine published in 2021"

Artificial Heterointerfaces Achieve Delicate Reaction Kinetics towards Hydrogen Evolution and Hydrazine Oxidation Catalysis

Abstract: Electrochemical water splitting for H2 production is limited by the sluggish anode oxygen evolution reaction (OER), thus using hydrazine oxidation reaction (HzOR) to replace OER has received great attention. Here we report the hierarchical porous nanosheet arrays with abundant Ni3 N-Co3 N heterointerfaces on Ni foam with superior hydrogen evolution reaction (HER) and HzOR activity, realizing working potentials of -43 and -88 mV for 10 mA cm-2 , respectively, and achieving an industry-level 1000 mA cm-2 at 200 mV for HzOR. The two-electrode overall hydrazine splitting (OHzS) electrolyzer requires the cell voltages of 0.071 and 0.76 V for 10 and 400 mA cm-2 , respectively. The H2 production powered by a direct hydrazine fuel cell (DHzFC) and a commercial solar cell are investigated to inspire future practical applications. DFT calculations decipher that heterointerfaces simultaneously optimize the hydrogen adsorption free energy (ΔGH* ) and promote the hydrazine dehydrogenation kinetics. This work provides a rationale for advanced bifunctional electrocatalysts, and propels the practical energy-saving H2 generation techniques.

Energy-saving hydrogen production by chlorine-free hybrid seawater splitting coupling hydrazine degradation.

Abstract: Seawater electrolysis represents a potential solution to grid-scale production of carbon-neutral hydrogen energy without reliance on freshwater. However, it is challenged by high energy costs and detrimental chlorine chemistry in complex chemical environments. Here we demonstrate chlorine-free hydrogen production by hybrid seawater splitting coupling hydrazine degradation. It yields hydrogen at a rate of 9.2 mol h–1 gcat–1 on NiCo/MXene-based electrodes with a low electricity expense of 2.75 kWh per m3 H2 at 500 mA cm–2 and 48% lower energy equivalent input relative to commercial alkaline water electrolysis. Chlorine electrochemistry is avoided by low cell voltages without anode protection regardless Cl– crossover. This electrolyzer meanwhile enables fast hydrazine degradation to ~3 ppb residual. Self-powered hybrid seawater electrolysis is realized by integrating low-voltage direct hydrazine fuel cells or solar cells. These findings enable further opportunities for efficient conversion of ocean resources to hydrogen fuel while removing harmful pollutants. Seawater electrolysis is promising for grid-scale H2 production without freshwater reliance, but high energy costs and detrimental Cl chemistry reduce its practical potential. Here, authors developed an energy-saving hybrid seawater electrolyzer for chlorine-free H2 production and N2H4 degradation.

Identification of M-NH2-NH2 Intermediate and Rate Determing Step for Nitrogen Reduction with Bioinspired Sulfur-bonded FeW Catalyst

Abstract: The multimetallic sulfur-framework catalytic site of biological nitrogenases allows the efficient conversion of dinitrogen (N 2 ) to ammonia (NH 3 ) under ambient conditions. Inspired by biological nitrogenases, a bimetallic sulfide material (FeWS x @FeWO 4 ) was synthesized as a highly efficient N 2 reduction (NRR) catalyst by sulfur substitution of the surface of FeWO 4 nanoparticles. Thus prepared FeWS x @FeWO 4 catalysts exhibit a relatively high NH 3 production rate of 30.2 ug h -1 mg -1 cat and a Faraday efficiency of 16.4% at - 0.45 V versus a reversible hydrogen electrode in a flow cell; these results have been confirmed via purified 15 N 2 -isotopic labeling experiments. In situ Raman spectra and hydrazine reduction kinetics analysis revealed that the reduction of undissociated hydrazine intermediates (M-NH 2 -NH 2 ) on the surface of the bimetallic sulfide catalyst is the rate-determing step for the NRR process. Therefore, this work can provide guidance for elucidating the structure-activity relationship of NRR catalysts.

Combined production of metallic-iron nanoparticles: exergy and energy analysis of two alternative processes using Hydrazine and NaBH4 as reducing agents

Abstract: This study deals with the simulation of two alternative processes for the coupled production of metallic iron nanoparticles and the necessary reducing agent: hydrated hydrazine and sodium borohydride. After carrying out a sensitivity analysis to identify the optimal operating conditions for each process, the results have been interpreted in the light of energy and exergy analysis. The study demonstrated that the sodium borohydride-based iron nanoparticles production is more profitable than the hydrazine-based one, because of a higher exergy efficiency as a consequence of lower exergy destruction value. The total heat duty required for the borohydride-based process was only 1.1 MWh with respect to 5 MWh for the hydrazine-based one. Conversely, cooling water and total power consumptions for the latter process are significantly lower than for the former one (2.33 t/h versus 26.87 t/h, and 2 kWh versus 88.7 kWh, respectively). Furthermore, as reported in the literature, the hydrazine-based process allows to produce high purity iron nanoparticles, since hydrazine is transformed completely in N2 during the process. Both processes were designed to produce 1765 kg/d of iron and the same amount of produced reducing agent was also stored as secondary product of the plant.

Development Trends on Nickel-Based Electrocatalysts for Direct Hydrazine Fuel Cells

Abstract: Low temperature hydrazine fuel cells have been advocated as potential energy carriers by virtue of their exceptional power densities and carbon free containing byproducts. However, the large‐scale application of these renewable energy systems has been extremely inhibited by the insufficient performance and high cost of the state‐of‐art platinum (Pt) catalysts. To pursue better activity, electrocatalysts must demonstrate low operating overpotentials and high tolerances to poisoning species, which are critical factors for increasing the energy conversion efficiency. Despite the tremendous progress of Pt‐based catalysts, controlling sluggish kinetics on microscopic surfaces is still a serious issue because the accumulation of reaction product slugs onto surface may impede the liquid fuel transport to catalytic sites, resulting in a low activity. Thus, the development of earth abundant electrocatalysts with an improved activity is unambiguously a principal requirement. In this review, recent trends in the rational design and synthesis of Ni‐based electrocatalysts with various compositions for hydrazine oxidation reaction (HzOR) are summarized. In particular, development of multicomponent compounds and employment of Ni‐based materials for HzOR are demonstrated to be effective approaches from tuning the electrochemical performance of Ni‐based catalyst materials. Moreover, some potential challenges and prospects are deliberated to further advance the improvement of Ni‐based materials for effective HzOR.

Vanadium Substitution Steering Reaction Kinetics Acceleration for Ni3N Nanosheets Endows Exceptionally Energy-Saving Hydrogen Evolution Coupled with Hydrazine Oxidation.

Abstract: Designing highly active transition-metal-based electrocatalysts for energy-saving electrochemical hydrogen evolution coupled with hydrazine oxidation possesses more economic prospects. However, the lack of bifunctional electrocatalysts and the absence of intrinsic structure-property relationship research consisting of adsorption configurations and dehydrogenation behavior of N2H4 molecules still hinder the development. Now, a V-doped Ni3N nanosheet self-supported on Ni foam (V-Ni3N NS) is reported, which presents excellent bifunctional electrocatalytic performance toward both hydrazine oxidation reaction (HzOR) and hydrogen evolution reaction (HER). The resultant V-Ni3N NS achieves an ultralow working potential of 2 mV and a small overpotential of 70 mV at 10 mA cm-2 in alkaline solution for HzOR and HER, respectively. Density functional theory calculations reveal that the vanadium substitution could effectively modulate the electronic structure of Ni3N, therefore facilitating the adsorption/desorption behavior of H* for HER, as well as boosting the dehydrogenation kinetics for HzOR.

Hydrazine Detection during Ammonia Electro-oxidation Using an Aggregation-Induced Emission Dye.

Abstract: Ammonia electro-oxidation is an extremely significant reaction with regards to the nitrogen cycle, hydrogen economy, and wastewater remediation. The design of efficient electrocatalysts for use in ...

Electrochemical Detection of Hydrazine by Carbon Paste Electrode Modified with Ferrocene Derivatives, Ionic Liquid, and CoS2-Carbon Nanotube Nanocomposite.

Abstract: The electrocatalytic performance of carbon paste electrode (CPE) modified with ferrocene-derivative (ethyl2-(4-ferrocenyl[1,2,3]triazol-1-yl)acetate), ionic liquid (n-hexyl-3-methylimidazolium hexafluorophosphate), and CoS2-carbon nanotube nanocomposite (EFTA/IL/CoS2-CNT/CPE) was investigated for the electrocatalytic detection of hydrazine CoS2-CNT nanocomposite was characterized by field emission scanning electron microscopy, X-ray powder diffraction, and transmission electron microscopy According to the results of cyclic voltammetry, the EFTA/IL/CoS2-CNT-integrated CPE has been accompanied by greater catalytic activities for hydrazine oxidation compared to the other electrodes in phosphate buffer solution at a pH 70 as a result of the synergistic impact of fused ferrocene-derivative, IL, and nanocomposite The sensor responded linearly with increasing concentration of hydrazine from 003 to 5000 μM with a higher sensitivity (0073 μA μM-1) and lower limit of detection (LOD, 0015 μM) Furthermore, reasonable reproducibility, lengthy stability, and excellent selectivity were also attained for the proposed sensor Finally, EFTA/IL/CoS2-CNT/CPE was applied for the detection of hydrazine in water samples, and good recoveries varied from 967 to 1030%

A Zeolitic-Imidazole Framework-Derived Trifunctional Electrocatalyst for Hydrazine Fuel Cells.

Abstract: Hydrazine fuel cells are promising sustainable power sources. However, the high price and limited reserves of noble metal catalysts that promote the sluggish cathodic and anodic electrochemical reactions hinder their practical applications. Reflecting the enhanced diffusion and improved kinetics of nanostructured non-noble metal electrocatalysts, we report an efficient zeolitic-imidazole framework-derived trifunctional electrocatalyst for hydrazine oxidation, oxygen, and hydrogen peroxide reduction. Experimental results and theoretical calculations corroborate that the nanocarbon architecture with abundant Co-N species enhances the electronic interaction and optimizes the energy barriers of anodic hydrazine oxidation and cathodic oxygen reduction. The resulting assembled hydrazine-oxygen fuel cell yields a cell voltage and power density of 0.74 V and 20.5 mW cm-2, respectively. Moreover, benefiting from the liquid-liquid diffusion, the hydrazine-hydrogen peroxide cell shows a boosted cell voltage and power density, corresponding to 1.68 V and 41.0 mW cm-2. This work offers a highly active non-noble metal multifunctional electrocatalyst with a pioneering diffusion philosophy in the liquid electrochemical cells.

Single Co-Atoms as Electrocatalysts for Efficient Hydrazine Oxidation Reaction.

Abstract: Single-atom catalysts (SACs) have aroused great attention due to their high atom efficiency and unprecedented catalytic properties. A remaining challenge is to anchor the single atoms individually on support materials via strong interactions. Herein, single atom Co sites have been developed on functionalized graphene by taking advantage of the strong interaction between Co2+ ions and the nitrile group of cyanographene. The potential of the material, which is named G(CN)Co, as a SAC is demonstrated using the electrocatalytic hydrazine oxidation reaction (HzOR). The material exhibits excellent catalytic activity for HzOR, driving the reaction with low overpotential and high current density while remaining stable during long reaction times. Thus, this material can be a promising alternative to conventional noble metal-based catalysts that are currently widely used in HzOR-based fuel cells. Density functional theory calculations of the reaction mechanism over the material reveal that the Co(II) sites on G(CN)Co can efficiently interact with hydrazine molecules and promote the NH bond-dissociation steps involved in the HzOR.

Heteroatom (N, O, and S)-Based Biomolecule-Functionalized Graphene Oxide: A Bifunctional Electrocatalyst for Enhancing Hydrazine Oxidation and Oxygen Reduction Reactions

Abstract: In this work, a new method is developed to synthesize an l-cysteine-based graphene oxide (l-Cy-rGO) electrocatalyst by a chemical synthesis approach. The electrocatalytic studies of l-Cy-rGO for th...

Redox-Mediated Ambient Electrolytic Nitrogen Reduction for Hydrazine and Ammonia Generation

Abstract: This work presents a redox-mediated electrolytic nitrogen reduction reaction (RM-eNRR) using polyoxometalate (POM) as the electron and proton carrier which frees the TiO2 -based catalyst from the electrode and shifts the reduction of nitrogen to a reactor tank. The RM-eNRR process has achieved an ammonium production yield of 25.1 μg h-1 or 5.0 μg h-1 cm-2 at an ammonium concentration of 6.7 ppm. With high catalyst loading, 61.0 ppm ammonium was accumulated in the electrolyte upon continuous operation, which is the highest concentration detected for ambient eNRR so far. The mechanism underlying the RM-eNRR was scrutinized both experimentally and computationally to delineate the POM-mediated charge transfer and hydrogenation process of nitrogen molecule on the catalyst. RM-eNRR is expected to provide an implementable solution to overcome the limitations in the conventional eNRR process.

Ratiometric covalent organic framework florescence sensor for detecting hydrazine produced from isoniazid metabolism in cell

Abstract: Designing luminescent COFs with high fluorescence quantum yield is always a huge challenge. In this work, we synthesized COF TzDha through Schiff base reaction between 4, 4′, 4′'-(1,3,5-triazine-2,4,6-triyl) trianiline (Tz) and 2,5-dihydroxyterephthalaldehyde (Dha), and post-modified COF TzDha-AC was grafted by refluxing in acetic anhydride. TzDha-AC shows higher relative fluorescence quantum yield (Φf) in various organic solvents and water, which is approximately 1.35 to 5.31 times to TzDha. What’s more surprising, TzDha-AC shows excellent ratiometric effect when it is used to detecte hydrazine (N2H4). Detection mechanism is attributed to that hydrazine prevents the intramolecular charge transfer (ICT) from benzene ring to triazine ring of TzDha-AC, thus the emission blue shifted from 601 nm to 526 nm. The detection limit (DL) of N2H4 is calculated to be 0.038 mM in the linear range of 0−10 mM. In addition, we also use TzDha-AC to detecte hydrazine produced from isoniazid metabolism in mouse liver cells and find that TzDha-AC could be a new material employed for simple isoniazid metabolism in cell.

The Electro-Oxidation of Hydrazine: A Self-Inhibiting Reaction

Abstract: The electro-oxidation of hydrazine to form dinitrogen is reported over a wide range of both pH and unbuffered conditions at glassy carbon electrodes It is shown that hydrazine molecules are only electro-active in their unprotonated form, N2H4, whereas the protonated species N2H5+ is electro-inactive The oxidation of N2H4 releases four protons per molecule which are diffusing away from the electrode to rapidly (on the voltammetric time scale) protonate unreacted N2H4 molecules diffusing to the electrode converting them into the electro-inactive form, N2H5+; the reaction is self-inhibiting, and the currents flowing are significantly reduced compared to those expected for a simple electrolytic conversion to an extent reflecting the pH and buffer content of the solution local to the electrode The local pH in turn is controlled partly by the quantity of protons released electrolytically The self-inhibition is modeled by solving the relevant transport equations with coupled homogeneous chemical kinetics, utilizing Marcus-Hush electron transfer, giving predicted reduced currents reflecting the pKa and kinetics of the N2H4/N2H5+ equilibrium in excellent agreement with experimental voltammetric wave shapes

Self-driven dual hydrogen production system based on bifunctional single-atomic Rh catalyst

Abstract: Electrocatalytic hydrogen evolution is an efficient and economical technology to address environmental contamination and energy crises, but the development of such a sustainable hydrogen production system with high-efficiency and energy-saving remains a great challenge. Here, we present a novel strategy to design a self-driven dual hydrogen production system for efficient hydrogen production based on highly dispersed Rh single atoms supported on oxygen-functionalized Ti3C2Ox MXene (Rh-SA/Ti3C2Ox) catalyst. The bifunctional Rh-SA/Ti3C2Ox catalyst exhibited remarkable catalytic activities towards both pH-universal hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR). Using Rh-SA/Ti3C2Ox as the electrode in the self-driven dual hydrogen production system by combing the Zn-H2 battery and overall hydrazine splitting units, an ultra-high H2 generation rate of 45.77 mmol h−1 can be achieved. Density functional theory calculations indicate that the atomically dispersed Rh single atoms can not only make the free energy of adsorbed H (ΔG*H) more thermoneutral for HER but also largely decrease the free-energy barrier of the dehydrogenation of adsorbed NHNH2 for HzOR.

Nitrocarbamoyl Azide O2NN(H)C(O)N3: A Stable but Highly Energetic Member of the Carbonyl Azide Family.

Abstract: The diazotization of nitrosemicarbazide (1) resulted in the formation and isolation of nitrocarbamoyl azide (2), which was thoroughly characterized by spectroscopic and structural methods. This compound shows surprising stability but also high reactivity and sensitivity, with a melting point of 72 °C and a detonative decomposition point at 83 °C. In addition, five selected salts were synthesized by careful deprotonation. The decomposition mechanism of 2 in solution was investigated and could be clarified by performing experiments using methanol and hydrazine as trapping reagents. The energetic and physicochemical properties of all these compounds were investigated and classified.

A cationic organic dye based on coumarin fluorophore for the detection of N2H4 in water and gas

Abstract: Hydrazine is an important chemical reagent, which has been widely used in chemical industry. However, the extensive usage of N2H4 poses a potential threat to water and air safety due to its good water solubility, strong volatility and high toxicity. Therefore, the rapid and reliable detection of hydrazine is of great significance. In this work, a cationic organic dye (probe) based on coumarin fluorophore with double emission wavelength (λex =390 nm, λem = 650/450 nm) was developed successfully. In aqueous solution, this probe can reliably detect hydrazine in a broad concentration range (2.05–996 μM) and a wide acidity range (pH 5–11) by the ratio-type fluorescence signal (F450/F650), and the detection time is about 20 min. Besides, it is worth pointing out that the test papers prepared by impregnating the organic dye on ordinary filter paper can realize the visual detection of hydrazine in water, beverages and gas within 2 min, showing excellent specificity and wide practicability.