Hydrazine Degradation Research Articles

Optimizing the Dehydrogenation Kinetics of Metal Nitrides for Energy‐Efficient Seawater Hydrogen Production at 2 A cm−2

AbstractSeawater hydrogen production, vital for sustainable energy solutions and freshwater preservation, faces challenges due to seawater complexity and high energy consumption. A strategy to modulate dehydrogenation kinetics of dual‐phase metal nitrides using low‐loaded Pt quantum dots (QDs), achieving stable and energy‐efficient hydrogen generation is introduced. The Pt QDs@Ni3N‐MoN/Ti catalyst displays outstanding bifunctional seawater catalytic performance, enabling efficient hydrogen production and hydrazine degradation in a flow anion exchange membrane water electrolysis (AEMWE) device. Operating at a low voltage of 1.41 V, it achieves 2 A cm−2 for 300 h, circumventing chlorine corrosion and yielding record‐breaking energy equivalent input (2.68 kWh m−3 H2 at 1 A cm−2), a 47.1% reduction compared to traditional methods. Integration with solar and biomass energy facilitates self‐powered hybrid seawater hydrogen production, highlighting its potential applications. This work facilitates energy‐efficient marine resource conversion to green hydrogen and offers viable insights into industrial hazardous pollutant degradation using metal‐nitride electrocatalysts.

Activating Interfacial Electron Redistribution in Lattice-Matched Biphasic Ni3N-Co3N for Energy-Efficient Electrocatalytic Hydrogen Production via Coupled Hydrazine Degradation.

The development of high-purity and high-energy-density green hydrogen through water electrolysis holds immense promise, but issues such as electrocatalyst costs and power consumption have hampered its practical application. In this study, we present a promising solution to these challenges through the use of a high-performance bifunctional electrocatalyst for energy-efficient hydrogen production via coupled hydrazine degradation. The biphasic metal nitrides with highly lattice-matched structures are deliberately constructed, forming an enhanced local electric field between the electron-rich Ni3N and electron-deficient Co3N. Additionally, Mn is introduced as an electric field engine to further activate electron redistribution. Our Mn@Ni3N-Co3N/NF bifunctional electrocatalyst achieves industrial-grade current densities of 500 mA cm-2 at 0.49 V without degradation, saving at least 53.3 % energy consumption compared to conventional alkaline water electrolysis. This work will stimulate the further development of metal nitride electrocatalysts and also provide new perspectives on low-cost hydrogen production and environmental protection.

Activating Interfacial Electron Redistribution in Lattice‐Matched Biphasic Ni3N‐Co3N for Energy‐Efficient Electrocatalytic Hydrogen Production via Coupled Hydrazine Degradation

AbstractThe development of high‐purity and high‐energy‐density green hydrogen through water electrolysis holds immense promise, but issues such as electrocatalyst costs and power consumption have hampered its practical application. In this study, we present a promising solution to these challenges through the use of a high‐performance bifunctional electrocatalyst for energy‐efficient hydrogen production via coupled hydrazine degradation. The biphasic metal nitrides with highly lattice‐matched structures are deliberately constructed, forming an enhanced local electric field between the electron‐rich Ni3N and electron‐deficient Co3N. Additionally, Mn is introduced as an electric field engine to further activate electron redistribution. Our Mn@Ni3N‐Co3N/NF bifunctional electrocatalyst achieves industrial‐grade current densities of 500 mA cm−2 at 0.49 V without degradation, saving at least 53.3 % energy consumption compared to conventional alkaline water electrolysis. This work will stimulate the further development of metal nitride electrocatalysts and also provide new perspectives on low‐cost hydrogen production and environmental protection.

Interface Engineering of a Hierarchical P-Modified Co/Ni3P Heterostructure for Highly Efficient Water Electrolysis Coupled with Hydrazine Degradation

Interface Engineering of a Hierarchical P-Modified Co/Ni₃P Heterostructure for Highly Efficient Water Electrolysis Coupled with Hydrazine Degradation

Low-content Pt-triggered the optimized d-band center of Rh metallene for energy-saving hydrogen production coupled with hydrazine degradation

Utilizing the hydrazine-assisted water electrolysis for energy-efficient hydrogen production shows a promising application, which relies on the development and design of efficient bifunctional electrocatalysts. Herein, we reported a low-content Pt-doped Rh metallene (Pt-Rhene) for hydrazine-assisted water electrolysis towards energy-saving hydrogen (H2) production, where the ultrathin metallene is constructed to provide enough favorable active sites for catalysis and improve atom utilization. Additionally, the synergistic effect between Rh and Pt can optimize the electronic structure of Rh for improving the intrinsic activity. Therefore, the required overpotential of Pt-Rhene is only 37 mV to reach a current density of −10 mA cm−2 in the hydrogen evolution reaction (HER), and the Pt-Rhene exhibits a required overpotential of only 11 mV to reach a current density of 10 mA cm−2 in the hydrazine oxidation reaction (HzOR). With the constructed HER-HzOR two-electrode system, the Pt-Rhene electrodes exhibit an extremely low voltage (0.06/0.19/0.28 V) to achieve current densities of 10/50/100 mA cm−2 for energy-saving H2 production, which greatly reduces the electrolysis energy consumption. Moreover, DFT calculations further demonstrate that the introduction of Pt modulates the electronic structure of Rh and optimizes the d-band center, thus enhancing the adsorption and desorption of reactant/intermediates in the electrocatalytic reaction.

Photovoltaics literature survey (No. 181)

Photovoltaics literature survey (No. 181)

Low power consumed PV-electrolysis with CoFeP nanowires for hydrazine-assisted hydrogen production

Water electrolysis is becoming increasingly important in green hydrogen production. However, it consumes large amount of power due to sluggish oxygen evolution reaction (OER). Recently, hydrazine oxidation reaction (HzOR) attracted significant attention in replacing OER owing to its low oxidation potential. In this study, CoFeP nanowires (NWs) are presented as a novel effective HzOR electrocatalyst. An array of CoFeP NWs was directly synthesized on a cobalt foam (CF) by cation exchange and subsequent phosphorization. Fe doping on CoP changes rate determine step of hydrazine degradation, required less energy of 0.17 eV, confirmed by DFT calculation. Our CoFeP/CF exhibited high HzOR activity with a low potential of −7 mV for generating a current density of 10 mA cm−2 and a Tafel slope of 29 mV dec−1, which is superior to noble metal catalysts. The overall hydrazine splitting (OHzS) of the combined Pt/CF||CoFeP/CF required remarkably low cell potential of only 63 mV to generate a current density of 10 mA cm−2. Furthermore, the unassisted solar hydrogen production was realized by assembling Pt/CF||CoFeP/CF with a single perovskite solar cell, generating a high current generation of 23 mA cm−2. This value is about two times higher than that of an unassisted overall water splitting system with a solar to hydrogen efficiency of 13.1%, confirming a great potential of our OHzS system in lowering power consumption of electrolysis.

The mechanism of methyl hydrazine degradation by supercritical water oxidation using ReaxFF simulation

Methyl hydrazine (MMH) is a key ingredient in rocket fuel as well as an important intermediate and solvent in organic synthesis. However, any remaining MMH in environment could be harmful to both people and the environment. In this work, we proposed a method for treating MMH pollution by supercritical water oxidation (SCWO) technology. Reactive molecular dynamics were used to reveal the microscopic mechanism of the oxidation decomposition of MMH. The results showed that the principle of SCWO is that the OH radicals are formed by the reaction between H2O and O2. It can effectively capture the H both in MMH and its decomposition fragments, thus speeding up the decomposition. At low temperature and low oxygen content, the initial decomposition of MMH has two main pathways: (1) CH3NHNH2 → CH3NH + NH2 (R1), and (2) CH3NHNH2 + OH → CH3NNH2 + H2O (R7). N2, CO2, and H2O are the final products. At high temperatures, the intermediate NH3 can be converted to N2. The activation energy of MMH decomposition with excess oxygen was also obtained by the Arrhenius equation as 29.3 kcal/mol.

Ammonia chemistry: Sounds better with ultrasound

Hydrazine is a chemical of utmost importance in our society, either for organic synthesis or energy use. The direct conversion of NH3 to hydrazine is highly appealing, but it remains a very difficult task because the degradation of hydrazine is thermodynamically more feasible than the cleavage of the N−H bond of NH3. As a result, any catalyst capable of activating NH3 will thus unavoidably decompose N2H4. Here, we show that cavitation bubbles, created by ultrasonic irradiation of aqueous NH3 at a high frequency, act as microreactors to activate and convert NH3 to NH species, without assistance of any catalyst, yielding hydrazine at the bubble–liquid interface. The compartmentation of in-situ-produced hydrazine in the bulk solution, which is maintained close to 30 °C, advantageously prevents its thermal degradation, a recurrent problem faced by previous technologies. This work also points towards a path to scavenge .OH radicals by adjusting the NH3 concentration.

Conversion of Ammonia to Hydrazine Induced by High-Frequency Ultrasound.

Hydrazine is a chemical of utmost importance in our society, either for organic synthesis or energy use. The direct conversion of NH3 to hydrazine is highly appealing, but it remains a very difficult task because the degradation of hydrazine is thermodynamically more feasible than the cleavage of the N-H bond of NH3 . As a result, any catalyst capable of activating NH3 will thus unavoidably decompose N2 H4 . Here we show that cavitation bubbles, created by ultrasonic irradiation of aqueous NH3 at a high frequency, act as microreactors to activate and convert NH3 to NH species, without assistance of any catalyst, yielding hydrazine at the bubble-liquid interface. The compartmentation of in-situ-produced hydrazine in the bulk solution, which is maintained close to 30 °C, advantageously prevents its thermal degradation, a recurrent problem faced by previous technologies. This work also points towards a path to scavenge . OH radicals by adjusting the NH3 concentration.

Conversion of Ammonia to Hydrazine Induced by High‐Frequency Ultrasound

AbstractHydrazine is a chemical of utmost importance in our society, either for organic synthesis or energy use. The direct conversion of NH3 to hydrazine is highly appealing, but it remains a very difficult task because the degradation of hydrazine is thermodynamically more feasible than the cleavage of the N−H bond of NH3. As a result, any catalyst capable of activating NH3 will thus unavoidably decompose N2H4. Here we show that cavitation bubbles, created by ultrasonic irradiation of aqueous NH3 at a high frequency, act as microreactors to activate and convert NH3 to NH species, without assistance of any catalyst, yielding hydrazine at the bubble–liquid interface. The compartmentation of in‐situ‐produced hydrazine in the bulk solution, which is maintained close to 30 °C, advantageously prevents its thermal degradation, a recurrent problem faced by previous technologies. This work also points towards a path to scavenge .OH radicals by adjusting the NH3 concentration.

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

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.

Atmospheric reaction of hydrazine plus hydroxyl radical

Understanding the mechanism of hydrazine oxidation reaction by OH radical along with the rate constants of all possible pathways leads to explain the fate of hydrazine in the atmosphere. In this article, the comprehensive mechanisms and kinetics of the hydrazine plus hydroxyl radical reaction have been investigated theoretically at different temperatures and pressures. To achieve the main goals, a series of high levels of quantum chemical calculations have been widely implemented in reliable channels of the H-abstraction, SN2, and addition/elimination reactions. The energy profile of all pathways accompanied by the molecular properties of the involved stationary points has been characterized at the MP2, M06-2X, and CCSD(T)/CBS levels. To estimate accurate barrier energies of the H-abstraction channels, large numbers of the CCSD (T) calculations in conjunction with various augmented basis sets have been implemented. The direct dynamic calculations have been carried out using the validated M06-2X/maug-cc-pVTZ level, and also by the CCSD(T) (energies) + MP2 (partition functions) level. The pressure-dependent rate constants of the barrierless pathways have been investigated by the strong collision approach. Therefore, the main behaviors of the N2H4 + OH reaction have been explored according to the influences of temperature and pressure on the computed rate coefficients within the well-behaved theoretical frameworks of the TST, VTST, and RRKM theories. It has been found that the H-abstraction mechanism (to form N2H3) is dominant relative to the SN2 reaction and OH-addition to the N center of N2H4 moiety (to form H2NOH + NH2). The computed high pressure limit rate constant of the main reaction pathway, k(298.15) = 7.31 × 10–11 cm3 molecule−1 s−1, has an excellent agreement with the experimental value (k (298.15) = (6.50 ± 1.3) × 10–11 cm3 molecule−1 s−1) recommended by Vaghjiani. Also, the atmospheric lifetime of hydrazine degradation by OH radicals has been demonstrated to be 32.80 to 1161.11 h at the altitudes of 0–50 km. Finally, the disagreement in the calculated rate constants between the previous theoretical study and experimental results has been rectified.

Organotrialkoxysilane-functionalized mesoporous Pd–Ni nanocatalyst for selective hydrazine decomposition and sensing

Organotrialkoxysilanes, particularly amino-glycidoxy and epoxy-functionalized alkoxysilanes, allow for the controlled synthesis of noble metal nanoparticles and bimetallic nanoparticles; these materials enable a concentration-dependent enhancement in resonance Rayleigh scattering, which may be useful for the selective detection of hydrazine. 3-aminopropyltrimethoxysilane (3-APTMS)-treated gold cations were converted into gold nanoparticles within a few seconds (< 1 min) in the presence of 3-glycidoxypropylytrimethoxysilane (3-GPTMS). Organotrialkoxysilane-functionalized gold nanoparticles that exhibit an average size of 9 nm or 17 nm were processed and evaluated for synchronous fluorescence-based detection of hydrazine. Organotrialkoxysilane allowed the formation of nickel–palladium bimetallic nanocrystallite-supported mesoporous silica nanoparticles. Organotrialkoxysilane served as a template for the stabilization and formation of bimetallic Pd–Ni nanocrystallites within a mesoporous silica nanoparticle (MSNP) support. The as-made heterogeneous support enabled real-time degradation of hydrazine.

Metal organic framework derived trifunctional NiCoP electrode for continuous solar-driven energy-saving hydrogen generation

Water splitting is a sustainable and clean hydrogen-production technology, but driven either by solar energy with natural intermittent, or by power grid with high cost, which is not conductive to sustainable development. Additionally, the sluggish anodic oxygen evolution reaction (OER) remains a huge obstacle for efficient hydrogen production. Herein, an intersected nanosheets decorating micro-walls structure nickel-cobalt phosphide grown on Ni foam electrode (NiCoP/NF) is prepared, and displays good hydrogen evolution reaction (HER), excellent hydrazine oxidation reaction (HzOR) and enhanced NiCoP/NF//Zn battery capacity performance. Based on the trifunctional NiCoP/NF electrode, a continuous solar-driven energy-saving hydrogen generation is constructed. The solar cells drive the efficient hydrogen production and hydrazine degradation plus simultaneously charge the NiCoP/NF//Zn battery during the day; then the charged NiCoP/NF//Zn battery provide high output voltage to drive hydrogen generation and hydrazine degradation at night. The continuous solar-driven energy-saving hydrogen generation plus sewage treatment strategy exhibits a new way for clean and sustainable energy supply plus curbing environmental pollution.

Major products and their formation and transformation mechanism through degrading UDMH wastewater via DBD low temperature plasma

ABSTRACT Unsymmetrical dimethylhydrazine (UDMH) is a liquid propellant widely used in aviation and aerospace. It produces a large amount of dimethyl hydrazine wastewater during long-term storage, testing, and reinjection. Traditional treatments produce numerous secondary contaminants such as residual high carcinogens, including N-nitrosodimethylamine (NDMA) and formaldehyde dimethylhydrazone (FDMH). In this paper, the dielectric barrier discharge (DBD) low temperature plasma technology is used to degrade the dimethyl hydrazine wastewater. Aiming at the problem of secondary pollutants in the degradation process, we used qualitative and quantitative methods to study the changes of NDMA and FDMH during the degradation of dimethyl hydrazine wastewater by DBD low temperature plasma. The kinetics of these two products showed that the degradation process of NDMA was consistent with the first-order reaction kinetics. Using density functional theory, we established molecular models of UDMH, NDMA and FDMH. According to the molecular orbital theory, the formation mechanism of NDMA and FDMH was calculated from three aspects: reaction structure, reaction path and energy change. We found that during the degradation of dimethyl hydrazine, the dimethyl hydrazine oxidation product was initiated by hydrogen abstraction on methyl (-CH3) and amine (-NH2). NDMA is produced by the oxidation of -NH2, whereas FDMH is mainly produced from dimethyl hydrazine and formaldehyde.

Self-Assembly-Induced Mosslike Fe2O3 and FeP on Electro-oxidized Carbon Paper for Low-Voltage-Driven Hydrogen Production Plus Hydrazine Degradation

Energy-saving electrolytic hydrogen production is the precondition for implementing large-scale hydrogen energy exploitation. Replacing the sluggish water oxidation reaction with thermodynamically more favorable pollutant electro-oxidation (degradation) is a very promising approach to combine energy-efficient hydrogen production and sewage treatment. Herein, a homologous asymmetrical two-electrode configuration, made up of self-assembly induced mosslike Fe2O3 and FeP on electro-oxidized carbon paper (ECP), was used to electrolyze the integrated hydrazine oxidation–hydrogen evolution system. The free-standing Fe2O3/ECP electrode was fabricated by pyrolyzing iron phthalocyanine/ECP self-assembly in air and serves as an anodic reaction catalyst. Subsequent phosphidation of the Fe2O3/ECP leads to the formation of the FeP/ECP catalyst for hydrogen evolution reaction. The cross-linked mosslike Fe2O3 and FeP nanoparticles densely covered on the surface of ECP provide richly exposed catalytic sites and the well-d...

Removal of Organic Matter and Ammonia Nitrogen in Azodicarbonamide Wastewater by a Combination of Power Ultrasound Radiation and Hydrogen Peroxide

A simple and efficient sonochemical method was developed for the degradation of organic matter and ammonia nitrogen in azodicarbonamide wastewater. The effects of initial pH, ultrasound format and peripheral water level on the sonolysis of hydrazine, urea, COD and ammonia nitrogen were investigated. It is found that the initial pH has a significant influence on the degradation of hydrazine and ammonia nitrogen, whereas this impact to urea is relatively small. It also shows that a noticeable enhancement of ammonia nitrogen removal could be achieved in a proper intermittent ultrasound operation mode, i.e., 1/1 min on/off mode. The height difference between the peripheral water level and the inner water level of the flask affects the efficiency of ultrasonic treatment as well.

Effect of coal ash on hydrazine degradation under stirring and ultrasonic irradiation conditions

The degradation of hydrazine (N2H4) with concentrations of 0.1–5.0mmol/L was investigated as a function of amount of coal ash (0.0–5.0wt%) under the stirring (300rpm) and ultrasonic irradiation (200kHz, 200W) conditions. It was found that the rate of decrease in the hydrazine concentration depended upon an amount of coal ash under the stirring and ultrasonic irradiation condition. It was considered under the stirring condition that hydrazine was adsorbed and degraded partly on coal ash. Furthermore, the sonochemically formed OH radicals were more effective in the hydrazine degradation than stirring condition in the presence of an intermediate amount of coal ash (0.6–2.4wt%), whereas the effect of OH radicals disappeared in the presence of coal ash more than 2.4wt%.

Hydrazine degradation by ultrasonic irradiation

The influence of pH on the degradation of hydrazine with a concentration of 0.1 mmol/L was investigated under the stirring (300 rpm) and ultrasonic irradiation conditions (200 kHz, 200 W) in the pH range of 1–9. It was found that the hydrazine degradation depended greatly upon pH under the ultrasonic irradiation condition, while it did not take place over the whole pH range under the stirring condition. Although it has been known that OH radicals and hydrogen peroxide are sonochemically formed from water, it was considered that the OH radicals played an important role of the hydrazine degradation, but not hydrogen peroxide. The pH dependence of the hydrazine degradation was discussed in terms of the relationship between the chemical structure and the basic dissociation constants of hydrazine.