Oxidation Of Hydrazine Research Articles

Interface engineering of amorphous/crystalline heterojunctions with synergistic Ru doping for efficient hydrazine oxidation assisted overall water splitting

Developing highly active electrocatalysts for overall water splitting is critical for the extensive implementation of renewable hydrogen.

Boosting hydrazine oxidation and hydrogen evolution catalysis with anchored Ru clusters by electronically tunable Ru–S–C bonds

A composite of Ru clusters supported on N, S co-doped hollow carbon spheres (Ru/NSCS) is synthesized by constructing robust Ru–S bonds, which exhibits excellent bifunctional catalytic activity for HER and HzOR.

Trace Ru atoms implanted into a Ni/Fe-based oxalate solid-solution-like with high-indexed facets for energy-saving overall seawater electrolysis assisted by hydrazine

Seawater splitting is considered as an economically appealing yet technically challenging approach to generate hydrogen fuel. Hampered by the sluggish oxygen evolution reaction (OER) and the detrimental effects of chlorine electrochemistry, designing robust and highly efficient electrocatalysts for the hydrogen evolution reaction (HER) in parallel with the hydrazine oxidation reaction (HzOR) is extremely imperative for hydrogen production in seawater mediums. Herein, we present a protocol that implants Ru nanospecies into a Ni/Fe-oxalate solid-solution-like with high-indexed facets to engineer an effective and novel-structured catalyst (Ru-(Ni/Fe)C2O4). Systematic experimental analyses alongside the theoretical calculations reveal that the synergistic effect of Ru nanospecies and high-index facets from (Ni/Fe)C2O4 endows Ru-(Ni/Fe)C2O4 with extraordinary activities of HER, OER and HzOR. When assembled into an electrolyzer, the cell voltage reduces to 0.01 V at 10 mA cm−2 for HER-HzOR coupling seawater splitting. Moreover, the system remains stable under 500 mA cm–2 at 80 °C for 50 h, almost meeting the requirements for quasi-industrial electrolysis. This work proposes a guideline for preparing multifunctional electrocatalysts and provides an effective strategy for developing seawater electrolysis to achieve a hydrogen economy society.

High efficient trifunctional electrocatalyst based on bimetallic oxide with rich oxygen vacancies towards electrochemical oxidation of small molecules at high current density

Exploiting low-cost, high-activity and robust-stability catalysts has become a meaningful and challenging research topic in the development of hydrogen production via electrochemical water splitting, meanwhile the as-synthesized materials exhibiting multi-functional electrocatalytic performance is highly desirable, but remains tremendous difficulty. Herein, a facile and scalable strategy is developed to synthesize nanowire-like NiCo2O4 arrays with space group Fd3¯m in-situ grown on cobalt foam (denoted as NiCo2O4/CF) via hydrothermal approach and air calcination treatment. The as-prepared nanoporous NiCo2O4/CF electrode possesses a high specific surface area, multiple redox couples and rich oxygen vacancies, thus displaying excellent tri-profitable catalytic activities towards hydrazine oxidation reaction (HzOR), urea oxidation reaction (UOR) and methanol oxidation reaction (MOR). Experimental results show that affording current densities of 10 and 100 mA cm−2 needs potentials of −0.172 and −0.149 V for HzOR, delivering 100 and 500 mA cm−2 current densities merely requires low potentials of 1.343 and 1.440 V for UOR. Impressively, for MOR, a potential of only 1.5 V is required to achieve a high current density of 1058 mA cm−2, outperforming most of the reported electrocatalysts. What's more, the NiCo2O4/CF electrode exhibits exceptional stability at a high current density of 100 mA cm−2 over 20 h for all of the three small molecules electro-oxidation. The current work provides a promising application opportunity for the nanowire-like NiCo2O4 in the aspect of energy-saving hydrogen generation with the assistance of small molecule electro-oxidation reaction.

Hydrazine High-Performance Oxidation and Sensing Using a Copper Oxide Nanosheet Electrocatalyst Prepared via a Foam-Surfactant Dual Template.

This work demonstrates hydrazine electro-oxidation and sensing using an ultrathin copper oxide nanosheet (CuO-NS) architecture prepared via a versatile foam-surfactant dual template (FSDT) approach. CuO-NS was synthesised by chemical deposition of the hexagonal surfactant Brij®58 liquid crystal template containing dissolved copper ions using hydrogen foam that was concurrently generated by a sodium borohydride reducing agent. The physical characterisations of the CuO-NS showed the formation of a two-dimensional (2D) ultrathin nanosheet architecture of crystalline CuO with a specific surface area of ~39 m2/g. The electrochemical CuO-NS oxidation and sensing performance for hydrazine oxidation revealed that the CuO nanosheets had a superior oxidation performance compared with bare-CuO, and the reported state-of-the-art catalysts had a high hydrazine sensitivity of 1.47 mA/cm2 mM, a low detection limit of 15 μM (S/N = 3), and a linear concentration range of up to 45 mM. Moreover, CuO-NS shows considerable potential for the practical use of hydrazine detection in tap and bottled water samples with a good recovery achieved. Furthermore, the foam-surfactant dual template (FSDT) one-pot synthesis approach could be used to produce a wide range of nanomaterials with various compositions and nanoarchitectures at ambient conditions for boosting the electrochemical catalytic reactions.

Ruthenium-doped 3D Cu2O nanochains as efficient electrocatalyst towards hydrogen evolution and hydrazine oxidation

The sluggish kinetics of oxygen evolution reaction (OER) hampers the conversion of renewable energies into hydrogen through an electrocatalytic process. Then, the hydrazine oxidation reaction (HzOR) is a promising anodic reaction to substitute OER, which can decrease the water-splitting voltage. Herein, self-supported ruthenium-doped cuprous oxide nanochains were synthesized on commercial copper foam (Ru-Cu2O/CF). The Ru-Cu2O/CF provides superior hydrogen evolution reaction (HER) and HzOR performances owing to its specific morphology, superhydrophilic surface, porous support and Ru doping. When used in alkaline or neutral electrolytes, the Ru-Cu2O/CF is capable of driving 10 mA cm−2 only at 31 and 51 mV, respectively. In HzOR, it is possible to achieve a superlow potential of − 41 mV at 10 mA cm−2. In an electrolytic cell with a Ru-Cu2O/CF both as cathode and anode, a voltage of 17.4 mV is needed to reach 10 mA cm−2, which is powered by renewable energies.

Rapid Melt-Quenching Enables General Synthesis of High-Loading Single-Atom Catalysts with Bicontinuous Nanoporous Structure.

Single-atom catalysts have attracted extensive attention due to their unique atomic structures and extraordinary activities in catalyzing chemical reactions. However, the lack of general and efficient approaches for producing high-density single atoms on suitably tailored supporting matrixes hinders their industrial applications. Here, a rapid melt-quenching strategy with high throughput to synthesize single atoms with high metal-atom loadings of up to 9.7 wt% or 2.6 at% on nanoporous metal compounds is reported, representing several-fold improvements compared to benchmarks in the literature. Mechanism characterizations reveal that the high-temperature melting provides the essential liquid environment and activation energy to achieve the atomization of metals, while the following rapid-quenching pins the isolated metal atoms and stabilizes the coordination environment. In comparison with carbon-supported single-atom catalysts, various collaboration combinations of single atoms and nanoporous metal compounds can be synthesized using the strategy, thus achieving efficient hydrazine oxidation-assisted H2 production. This synthesis protocol is highly compatible with automatic operation, which provides a feasible and general route to design and manufacture specific single-atom catalysts with tunable atomic metal components and supporting matrixes, thus promoting the deployment of single-atom catalysts for various energy technology applications.

Enhancing the total nitrogen removal efficiency of anaerobic ammonium oxidation (anammox) with two types of biochars

Although anaerobic ammonium oxidation (anammox) process has the advantage of energy neutrality and resource positivity, the accumulation of nitrate in the effluent decrease the total nitrogen (TN) removal efficiency. Biochar has been reported to improve nitrogen removal efficiency in anammox process. Biochars derived from different raw materials are different in electron transfer capacity, soluble composition, and functional groups. However, the specific effect of biochar characteristics on anammox bacteria and the mechanism are still elusive. The present study evaluated the effect and potential mechanism of coconut shell and coal biochars on facilitating TN removal of anammox process. Results showed that quartz sand (42.29% ± 12.31%) and PE carrier (42.47% ± 11.85%) had no evident effect on the TN removal compared with control reactor (41.46% ± 11.33%). Both types of biochar could promote TN removal efficiency (58.90% ± 13.81% and 55.80% ± 12.55% in coconut and coal biochars) despite the difference in surface groups and electron transfer capacity. Biochar could provide electron to initiate nitrite reduction and then receive electron from hydrazine oxidation, leading to a lower ΔNO3--N/ΔNH4+-N in coconut (0.14) and coal biochar (0.16) than control reactor (0.26). Genus Candidatus Brocadia (2.18% and 2.68% in coconut and coal, respectively) was outcompeted by Candidatus Jettenia (11.10% and 20.19%) in the presence of biochar. The abundance of Limnobacter was also increased in the presence of biochar, which was likely because they could improve the electron transfer between biochar and anammox bacteria. The findings of the present study provide insights into the role of biochar in mediating nitrite reduction in the anammox process.

Electronic distribution tuning of vanadium-cobalt bimetallic MOFs for highly efficient hydrazine-assisted energy-saving hydrogen production

Substituting oxygen evolution reaction (OER) by hydrazine oxidation reaction (HzOR) is a very efficient energy-saving strategy for water electrolysis. Therefore, exploring low-cost and efficient catalysts for HzOR and hydrogen evolution reaction (HER) is very significant to address the great challenge for hydrogen production. Herein, a series of vanadium-cobalt bimetal-organic frameworks [Vx-Co-MOFs: x represents the mass fraction of V element: V/(V+Co)] are synthesized through a one-pot hydrothermal method. The V41.7wt%-Co-MOF exhibits excellent multifunctional catalytic activity. The overall hydrazine splitting (OHzS) delivers 10 mA cm−2 at an ultralow cell voltage of 0.21 V. The superior performance can be ascribed to that the presence of cobalt-vanadium bimetals, which leads to the lattice disorder, an increase in specific surface area and mesoporous structure in V41.7wt%-Co-MOF, thus ensuring the exposure of more active sites. Particularly, the in-situ Raman test indicates that V41.7wt%-Co-MOF is partially converted into Co(OH)2 in the process of electrolysis to form a heterostructure. DFT calculations further show the charge transfer between Co and V, along with the good synergy between V-Co-MOF and Co(OH)2 improves the HER and HzOR performance of V41.7wt%-Co-MOF. This study provides a promising Co-V based catalyst for energy saving hydrogen production.

Interface Engineering of SRu-mC3N4 Heterostructures for Enhanced Electrochemical Hydrazine Oxidation Reactions

Hydrazine oxidation in single-atom catalysts (SACs) could exploit the efficiency of metal atom utilization, which is a substitution for noble metal-based electrolysers that results in reduced overall cost. A well-established ruthenium single atom over mesoporous carbon nitride (SRu-mC3N4) catalyst is explored for the electro-oxidation of hydrazine as one of the model reactions for direct fuel cell reactions. The electrochemical activity observed with linear sweep voltammetry (LSV) confirmed that SRu-mC3N4 shows an ultra-low onset potential of 0.88 V vs. RHE, and with a current density of 10 mA/cm2 the observed potential was 1.19 V vs. RHE, compared with mesoporous carbon nitride (mC3N4) (1.77 V vs. RHE). Electrochemical impedance spectroscopy (EIS) and chronoamperometry (i-t) studies on SRu-mC3N4 show a smaller charge-transfer resistance (RCt) of 2950 Ω and long-term potential, as well as current stability of 50 h and 20 mA/cm2, respectively. Herein, an efficient and enhanced activity toward HzOR was demonstrated on SRu-mC3N4 from its synergistic platform over highly porous C3N4, possessing large and independent active sites, and improving the subsequent large-scale reaction.

Integrating electrophilic and nucleophilic dual sites on heterogeneous bimetallic phosphide via enhancing interfacial electronic field to boost hydrazine oxidation and hydrogen evolution

Integrating dual sites of hydrazine oxidation reaction (HzOR) and hydrogen evolution reaction (HER) into a catalyst is highly desirable for energy-saving hydrogen production but remains challenges. Herein, we fabricate a heterogeneous nanowire array consisting of CoP and N-doped Ni5P4 on carbon fiber paper (N-Ni5P4@CoP/CFP), in which the N atoms can be selectively incorporated into Ni5P4 to change the Ni coordination that can regulate interfacial electronic field and thus improve the charge transfer from CoP to N-Ni5P4. Such an interfacial charge redistribution can induce the formation of well-defined electrophilic and nucleophilic sites, which could optimize hydrazine dehydrogenation kinetics and hydrogen adsorption free energy (ΔGH*), thus achieving splendid HzOR and HER activities. The commercial solar cells and homemade lemon batteries driven overall hydrazine splitting (OHzS) electrolyzer inspires its practical applications. Integrating the electrophilic and nucleophilic dual sites via interfacial electronic field regulation provides a new inspiration for efficiently catalyzing HzOR and HER.

Electrodeposition of self-supported transition metal phosphides nanosheets as efficient hydrazine-assisted electrolytic hydrogen production catalyst

The synthesis of electrocatalysts which used simultaneously as electrodes for the hydrazine oxidation reaction (HzOR), and hydrogen evolution reaction (HER) can significantly improve the efficiency of hydrogen production in the water splitting process. Here, Ni–Co–Fe–P binder-free nanosheets were fabricated using the electrochemical deposition method and used as an effective, stable, and cost-effective electrode for hydrazine-assisted electrochemical hydrogen production. Taking advantage of high surface area, being binder-free, and synergistic effect between the elements in the electrode composition, this electrode showed unique electrocatalytic activity and stability. When this electrode was used as a bifunctional electrode for HzOR-HER, a cell voltage of 94 mV was required to reach a current density of 10 mA cm−2. The results of this study indicated that the Ni–Co–Fe–P electrode is an excellent candidate for the hydrogen production industry.

Identifying the roles of Ru single atoms and nanoclusters for energy-efficient hydrogen production assisted by electrocatalytic hydrazine oxidation

With a much lower thermodynamic reaction potential, the hydrazine oxidation reaction (HzOR) can be employed as an alternative of water oxidation reaction to integrate with the cathodic hydrogen evolution reaction (HER), accomplishing an energy-efficient H2 production. The realization of this necessitates the development of the excellent bifunctional electrocatalysts for both HER and HzOR. Herein, a common Ru complex was applied to prepare a Ru/porous N-doped carbon composite (Ru/PNC) simultaneously containing abundant Ru single atoms (SAs) and ultrafine Ru nanoclusters (1.7 nm). Firstly, the new Ru/PNC catalysts containing both metal-metal as well as metal-substrate interactions display superb HER and HzOR activities in alkaline and neutral electrolytes, both greatly surpassing the sole Ru nanoparticles or Ru SAs sample. The controlled experiments and theoretical studies unravel water dissociation and H ad-desorption occurs on Ru SAs and nanoclusters, respectively, involving the proton transfer between them during the HER process, while HzOR is mainly proceeded on Ru SAs sites. Secondly, the alkaline overall hydrazine splitting with Ru/PNC only demands a voltage of 0.19 V to achieve 100 mA cm−2, demonstrating the huge energy-saving advantage compared with conventional water splitting. Additionally, the hydrogen generation can be readily operated with the hydrazine fuel cell and commercial solar cell with the appreciable H2 production rate of 32.7 and 27.1 mL cm−2 h−1, respectively.

Accelerated dehydrogenation kinetics through Ru, Fe dual-doped Ni2P as bifunctional electrocatalyst for hydrazine-assisted self-powered hydrogen generation

Seawater electrolysis is a potential way to realize the large-scale hydrogen production without relying on freshwater resources, but limited by the chlorine evolution reaction (ClER) on the anode and high potential for seawater electrolysis. In this work, MOF-derived Ru, Fe dual-doped Ni2P nanosheets (RuFe-Ni2P@NF) is constructed to serve as bifunctional catalyst for chlorine-free hydrogen production by hybrid hydrogen evolution reaction (HER) coupled with hydrazine oxidation reaction (HzOR) in seawater. As an ideal bifunctional electrocatalyst for overall hydrazine splitting (OHzS) in seawater, RuFe-Ni2P@NF catalyst only needs 0.69 V to achieve 1000 mA cm−2. Moreover, the energy-saving H2 production is realized by utilizing OHzS unit, which can save 4.70 W · h of electricity compared with the N2H4-free unit for producing 1.0 L of H2. Moreover, the direct hydrazine fuel cell (DHzFC) is assembled to drive OHzS to realize the self-powered H2 production. The industrial hydrazine sewage can serve as feed for the above eletrolysis system, which has been degraded to ∼ 8 ppb rapidly. DFT calculations demonstrate that the Ru and Fe dual-doping can not only realize the thermoneutral ΔGH* for HER but also decrease the free energy of dehydrogenation of *N2H3 to *N2H2 for HzOR, realizing the intrinsically enhanced dehydrogenation kinetics.

Decoupled Electrochemical Hydrazine "Splitting" via a Rechargeable Zn-Hydrazine Battery.

Hydrogen generation via electrochemical splitting plays an important role to achieve hydrogen economy. However, the large-scale application is highly limited by high cost and low efficiency. Herein, a new type of rechargeable Zn-hydrazine (Zn-Hz) battery is proposed and realized by a bifunctional electrocatalyst based on two separate cathodic reactions of hydrogen evolution (discharge: 2H2 O + 2e- → H2 + 2OH- ) and hydrazine oxidation (charge: ). This Zn-Hz battery, driven by temporally decoupled electrochemical hydrazine splitting on the cathode during discharge and charge processes, can generate separated hydrogen without purification. When the highly active bifunctional cathode of 3D Mo2 C/Ni@C/CS is paired with Zn foil, the Zn-Hz battery can achieve efficient hydrogen generation with a low energy input of less than 0.4V (77.2kJmol-1 ) and high energy efficiency of 96%. Remarkably, this battery exhibits outstanding long-term stability for 600 cycles (200h), achieving continuous hydrogen production on demand, which presents great potential for practical application.

In situ electronic redistribution of Ni2P hierarchical structure for energy-saving hydrogen production in seawater

Seawater electrolysis coupled with hydrazine oxidation is an effective strategy for energy efficient hydrogen production. In this paper, Fe, F co-doping Ni2P wrapped by N-doped carbon layers having distinct 2D/3D structure (Fe/F-Ni2P@NC) was synthesized on nickel foam. DFT result reveals that due to the Fe, F dual doping to realize the electronic redistribution. In alkaline seawater the Fe/F-Ni2P@NC exhibit excellent bifunctional catalytic performance for hydrazine oxidation reaction (HzOR) and hydrogen evolution reaction (HER). In comparison with the overall water splitting (OWS) seawater system, it is encouraging that the overall hydrazine splitting (OHzS) system can save 3.35 kW·h to produce 1.0 m3 of H2. Moreover, the hydrazine sewage of industry is utilized as feedstock for electrolysis system, which can be rapidly degraded to ∼5 ppb. This research provides an effective method for the preparation of efficient catalysts and the energy expanse.

Bifunctional zeolitic imidazolate framework-67 coupling with CoNiSe electrocatalyst for efficient hydrazine-assisted water splitting

Employing hydrazine oxidation reaction (HzOR) to substitute oxygen evolution reaction (OER) has been regarded as a promising alternative to realize energy-saving hydrogen generation during water splitting. Herein, we introduce a combined experimental and theoretical investigation of zeolitic imidazolate framework-67 coupling with CoNiSe-3 (ZIF67@CoNiSe-3) as an efficient electrocatalyst towards both hydrogen evolution reaction (HER) and HzOR. The as-prepared ZIF67@CoNiSe-3 with nanoflower structure and highly porous ultrathin nanosheet arrays can endow advanced electrocatalytic properties for HER and HzOR. For instance, ZIF67@CoNiSe-3 demands a low overpotential of 49 mV to generate 10 mA·cm−2 with a small Tafel slope of 41.4 mV·dec-1 for HER, while it can also reach an ultrahigh current density of 400 mA cm−2 at 0.13 V vs reversible hydrogen electrode (RHE) with a small Tafel slope of 44.3 mV·dec-1 for HzOR. When using ZIF67@CoNiSe-3 as both cathode and anode in a two-electrode cell for overall hydrazine splitting (OHzS), it only needs an ultralow cell voltage of 0.45 V to produce 100 mA·cm−2 with a remarkable long-term stability of 30 h. Impressively, first-principles calculations (DFT) have been employed to investigate the electrocatalytic mechanisms of ZIF67@CoNi-3 for HER and HzOR. This research could provide an efficient strategy for energy-saving H2 production during water splitting by incorporating a low-cost yet high-performance bifunctional catalyst.

Benzotiyofen@Pd as an efficient and stable catalyst for the electrocatalytic oxidation of hydrazine

• New organic molecule was synthesized and investigated its anode catalyst performance. • CV, CA, and EIS methods are used to determination of the hydrazine oxidation activities. • The specific activity of organic catalyst is found as 25.811 mA/cm 2 . • Pd metal is electrochemically deposited on the organic catalyst, the catalytic activity increased the 80.930 mA/cm 2 . • This activity is higher than the current expensive metal anode catalyst. An efficient methods for the synthesis of 2-(2,5-dimethylphenyl)-3-iodobenzo[ b ]thiophene ( 4 ) is described, and investigated its anode catalyst performance by using electrochemical methods (CV, CA and EIS). When 2-(2,5-dimethylphenyl)-3-iodobenzo[ b ]thiophene ( 4 ) is applied, the specific activity is found as 25.811 mA/cm 2 . Interestingly, when Palladium (Pd) is electrochemically deposited on the benzothiophene derivative, the catalytic activity increased the 80.930 mA/cm 2 . This result is highest than the current metal based anode catalyst. Moreover, EIS and CA measurements display that Pd doped benzothiophene organic catalyst have high stability, and give the low charge transfer resistance. Energy dispersive X-ray (SEM-EDX), electron microscopy, TEM are used for the determination of its surface morphology. As a result, 2-(2,5-dimethylphenyl)-3-iodobenzo[ b ]thiophene ( 4 ) may be alternative electro-catalysts in fuel cell applications.

A Janus heteroatom-doped carbon electrocatalyst for hydrazine oxidation.

The trade-off between the intrinsic activity and electronic conductivity of carbon materials is a major barrier for electrocatalysis. We report a Janus-type carbon material combining electrically conductive nitrogen-doped carbon (NC) and catalytically active boron, nitrogen co-doped carbon (BNC). The integration of NC with BNC can not only ensure high electronic conductivity of the hybrid, but also achieve an enhancement in the intrinsic activity of the BNC side due to the electron redistribution on their coupling interfaces. In the electrocatalytic hydrazine oxidation reaction (HzOR), the Janus carbon electrocatalyst exhibits superior activity than their single counterparts and simple physical mixtures. Density functional theory calculations reveal that the NC/BNC interfaces simultaneously promote efficient electron transport and decrease the free energy of the rate-determining step in the HzOR process.

Efficient CoNi-bimetal phosphide embedded carbon matrix derived from a novel phosphonate complex for hydrazine-assisted electrolytic hydrogen production

Electrochemical water splitting is considered as a sustainable and clean technology for hydrogen production, but is still limited by the sluggish kinetics of anodic oxygen evolution reaction (OER). Hydrazine oxidation reaction (HzOR) requires much lower thermodynamic oxidation potential and produces zero-carbon molecules, thus becoming a promising alternative to replace OER for realizing energy-saving hydrogen production. Herein, a CoNi-bimetal phosphide nanoparticles embedded P doped carbon matrix structure ((Co0.6Ni0.4)2P@PC) is constructed via annealing a novel precursor composed of CoNi-bimetal sites and P contained ligands for hydrazine-assisted water splitting. The P element can simultaneously in situ phosphorize the metal sites and carbon atoms. The (Co0.6Ni0.4)2P@PC exhibits outstanding hydrogen evolution reaction (HER) performance with an overpotential of 67.9 mV at 10 mA cm−2 and requires an ultralow potential of -83 mV at 10 mA cm−2 for HzOR in alkaline electrolyte. Furthermore, the electrolyzer assembled with the (Co0.6Ni0.4)2P@PC as both cathode and anode delivers a cell voltage of merely 0.048 V which is much lower compared with the OER-HER system (1.60 V) for reaching 10 mA cm−2. The present work develops an eco-friendly synthetic method for designing low-cost and highly efficient carbon matrix incorporated phosphide electrocatalyst for energy-saving hydrogen production.