Anodic Oxidation Of Hydrazine Research Articles

Lattice Strain Engineering of Ni2 p Enables Efficient Catalytic Hydrazine Oxidation-assisted Hydrogen Production.

Hydrazine-assisted water electrolysis provides new opportunities to enable energy-saving hydrogen production while solve the issue of hydrazine pollution. Here, wereport the synthesis of compressively strained Ni2 P as a bifunctional electrocatalyst for boosting both the anodic hydrazine oxidation reaction (HzOR) and cathodic hydrogen evolution reaction (HER). Different from a multistep synthetic method that induces lattice strains by creating core-shell structures, wedevelop a facile strategy to tune strains of Ni2 P via the dual cation-codoping. The obtained Ni2 P with a compressive strain of -3.62% exhibits significantly enhanced activity for both the HzOR and HER than counterpart with tensile strains and without strains. Consequently, the optimized Ni2 P delivers current densities of 10 and 100mA cm-2 at small cell voltages of 0.16 and 0.39V for hydrazine-assisted water electrolysis, respectively. Density functional theory (DFT) calculations reveal that the compression strain promotes water dissociation and concurrently tunes the adsorption strength of hydrogen intermediates, thereby facilitating the HER process on Ni2 P. As for the HzOR, the compression strain reduces the energy barrier of potential-determining step (PDS) for the dehydrogenation of *N2 H4 to *N2 H3 . Clearly, this work not only paves a facile pathway to synthesis lattice-strained electrocatalysts via the dual cations-codoping. This article is protected by copyright. All rights reserved.

Directional manipulation of electron transfer in copper/nitrogen doped carbon by Schottky barrier for efficient anodic hydrazine oxidation and cathodic oxygen reduction

Development of bifunctional hydrazine oxidation and oxygen reduction electrocatalysts with high activity and stability is of great significance for the implementation of direct hydrazine fuel cells. Combining zero-dimensional metal nanoparticles with three-dimensional nitrogen-doped carbon nanosheets is an attractive strategy for balancing performance and cost. However, the precise construction of these composites remains a significant challenge, and thorough study of their interaction mechanisms is lacking. Herein, the CuNPs/CuSA-NPCF catalyst was constructed by anchoring copper nanoparticles on a three-dimensional nitrogen-doped porous carbon nanosheet framework through coordination of polyvinyl pyrrolidone and copper ions. The Schottky barrier of metal–semiconductor matched the Fermi level of the rectifying contact, thus enabling directional electron transfer. The resulting electron-deficient Cu nanoparticles surface exhibited Lewis acidity, which was beneficial to adsorption of hydrazine molecule. While the electron-enriched Cu–N4/carbon surface improved the adsorption of oxygen molecule, and accelerated electron supply from Cu-N4 active sites to various oxygen intermediates. The CuNPs/CuSA-NPCF Mott-Schottky catalyst exhibited excellent catalytic activity for hydrazine oxidation reaction and oxygen reduction reaction in an alkaline media. The directional manipulation of electron transfer in heterogeneous materials was an attractive universal synthesis method, providing new approach for the preparation of efficient and stable hydrazine fuel cell catalysts.

Leveraging Metal Nodes in Metal-Organic Frameworks for Advanced Anodic Hydrazine Oxidation Assisted Seawater Splitting.

Metal-organic frameworks (MOFs) show great promise for electrocatalysis owing to their tunable ligand structures. However, the poor stability of MOFs impedes their practical applications. Unlike the general pathway for engineering ligands, we report herein an innovative strategy for leveraging metal nodes to improve both the catalytic activity and the stability. Our electrolysis cell with a NiRh-MOF||NiRh-MOF configuration exhibited 10 mA cm-2 at an ultralow cell voltage of 0.06 V in alkaline seawater (with 0.3 M N2H4), outperforming its counterpart benchmark Pt/C||Pt/C cell (0.12 V). Impressively, the incorporation of Rh into a MOF secured a robust stability of over 60 h even when working in the seawater electrolyte. Experimental results and theoretical calculations revealed that Rh atoms serve as the active sites for hydrogen evolution while Ni nodes are responsible for the hydrazine oxidation during the hydrazine oxidation assisted seawater splitting. This work provides a paradigm for green hydrogen generation from seawater.

Bifunctional Ultrathin RhRu0.5 -Alloy Nanowire Electrocatalysts for Hydrazine-Assisted Water Splitting.

Hydrazine-assisted water electrolysis offers a feasible path for low-voltage green hydrogen production. Herein, the design and synthesis of ultrathin RhRu0.5 -alloy wavy nanowires as bifunctional electrocatalysts for both the anodic hydrazine oxidation reaction (HzOR) and the cathodic hydrogen evolution reaction (HER) is reported. It is shown that the RhRu0.5 -alloy wavy nanowires can achieve complete electrooxidation of hydrazine with a low overpotential and high mass activity, as well as improved performance for the HER. The resulting RhRu0.5 bifunctional electrocatalysts enable, high performance hydrazine-assisted water electrolysis delivering a current density of 100mAcm-2 at an ultralow cell voltage of 54 mV and a high current density of 853mAcm-2 at a cell voltage of 0.6V. The RhRu0.5 electrocatalysts further demonstrate a stable operation at a high current density of 100mAcm-2 for 80 hours of testing period with little irreversible degradation. The overall performance greatlyexceeds that of the previously reported hydrazine-assisted water electrolyzers, offering a pathway for efficiently converting hazardous hydrazine into molecular hydrogen.

Ligand-free monophasic CuPd alloys endow boosted reaction kinetics toward energy-efficient hydrogen fuel production paired with hydrazine oxidation

Optimizing the structure and components is a prevalent strategy for increasing electrocatalytic energy-saving H2 fuel production. One of the sustainable and efficient techniques is electrocatalytic water splitting for H2 generation, but it is still restricted by the kinetically sluggish OER. Due to the lower standard oxidation potential of −0.33 V, replacing the OER with anodic hydrazine oxidation reaction (HzOR) is an effective way to extensively reduce the use of electricity in water electrolysis. Through alloying, the semiconductor and adsorption characteristics of Cu, interlaced by Pd2+ solution on the Pd surface by pulsed laser ablation (PLA) in methanol, are selectively altered to maximize cathodic HER and anodic HzOR performance. The optimal Cu1Pd3/C ratio demonstrates outstanding HER performance with a low overpotential of 0.315 V at 10 mA cm−2, as well as an ultralow overpotential of 0.560 V for HzOR in 0.5 M N2H4/1.0 M KOH. Furthermore, the constructed HzOR-assisted electrolyzer cell with Cu1Pd3/C ∥ Cu1Pd3/C as anode and cathode exhibits a cell voltage of 0.505 V at 10 mA cm−2 with exceptional endurance over 5 h. The current study advances competent CuPd alloys as multifunctional electrocatalysts for H2 fuel production by using a HzOR-assisted energy-efficient electrolyzer.

Thermally constructed stable Zn-doped NiCoOx-z alloy structures on stainless steel mesh for efficient hydrogen production via overall hydrazine splitting in alkaline electrolyte

Hydrogen has a high energy density of approximately 120 to 140 MJ kg−1, which is very high compared to other natural energy sources. However, hydrogen generation through electrocatalytic water splitting is a high electricity consumption process due to the sluggish oxygen evolution reaction (OER). As a result, hydrogen generation through hydrazine-assisted water electrolysis has recently been intensively investigated. The hydrazine electrolysis process requires a low potential compared to the water electrolysis process. Despite this, the utilization of direct hydrazine fuel cells (DHFCs) as portable or vehicle power sources necessitates the development of inexpensive and effective anodic hydrazine oxidation catalysts. Here, we prepared oxygen-deficient zinc-doped nickel cobalt oxide (Zn-NiCoOx-z) alloy nanoarrays on stainless steel mesh (SSM) using a hydrothermal synthesis method followed by thermal treatment. Furthermore, the prepared thin films were used as electrocatalysts, and the OER and hydrazine oxidation reaction (HzOR) activities were investigated in three- and two-electrode systems. In a three-electrode system, Zn-NiCoOx-z/SSM HzOR requires −0.116 V (vs RHE) potential to achieve a 50 mA cm−2 current density, which is dramatically lower than the OER potential (1.493 V vs RHE). In a two-electrode system (Zn-NiCoOx-z/SSM(-)∥Zn-NiCoOx-z/SSM(+)), the overall hydrazine splitting potential (OHzS) required to reach 50 mA cm−2 is only 0.700 V, which is dramatically less than the required potential for overall water splitting (OWS). These excellent HzOR results are due to the binder-free oxygen-deficient Zn-NiCoOx-z/SSM alloy nanoarray, which provides a large number of active sites and improves the wettability of catalysts after Zn doping.

Hierarchically nanostructured Ni2Fe2N as an efficient electrocatalyst for hydrazine oxidation reaction

A Ni foam-supported, hierarchically nanostructured Ni 2 Fe 2 N nanoflowers (Ni 2 Fe 2 N/NF) exhibits high activity and good operation stability towards hydrazine electrooxidation. • Hierarchically nanostructured Ni 2 Fe 2 N was anchored on Ni foam by a two-step procedure. • Ni 2 Fe 2 N/NF exhibits higher HzOR activity than the top-notch electrocatalysts hitherto reported. • Ni 2 Fe 2 N/NF shows high reaction selectivity toward faradic decomposition of hydrazine. The application of direct hydrazine fuel cells (DHFCs) as portable or vehicular power sources calls for the development of cheap and efficient catalysts for the anodic hydrazine oxidation reaction (HzOR). Herein, we report the facile fabrication of a Ni-foam-supported, hierarchically nanostructured Ni 2 Fe 2 N (Ni 2 Fe 2 N/NF) as a high-performance HzOR catalyst. The Ni 2 Fe 2 N/NF catalyst was fabricated by a simple hydrothermal method and a subsequent nitridation treatment. The thus-prepared Ni 2 Fe 2 N possesses high intrinsic activity towards HzOR, good electronic conductivity as well as a hierarchical architecture, which endows the catalyst with abundant active sites and improved mass transfer properties. Benefiting from these attributes, Ni 2 Fe 2 N/NF demonstrates highly efficient HzOR performance with a high current density of 1017 mA cm −2 at 0.3 V versus RHE, excellent stability and a nearly 100% selectivity for the faradaic hydrazine decomposition following 4-electron pathway, surpassing most previously reported top-notch HzOR electrocatalysts.

Dual-strategy of hetero-engineering and cation doping to boost energy-saving hydrogen production via hydrazine-assisted seawater electrolysis

When compared with pure water, hydrogen produced by seawater electrolysis has a better practical application potential. By replacing the oxygen evolution reaction (OER) and competitive chlorine evolution reaction (ClER) with the thermodynamically favorable anodic hydrazine oxidation reaction (HzOR) in alkaline seawater, energy-saving hydrogen production can be achieved. In this study, Fe/Co dual-doped Ni2P and MIL-FeCoNi heterostructures (FeCo-Ni2P@MIL-FeCoNi) arrays with simultaneous cation doping and hetero-engineering provide excellent bifunctional electrocatalytic performance for HzOR and hydrogen evolution reaction (HER) in alkaline seawater electrolyte. Overall hydrazine splitting (OHzS) in seawater is impressive, with a low cell voltage of only 400 mV required to reach 1000 mA cm−2 and stable operation for 1000 h to maintain above 500 mA cm−2. As a proof-of-concept, the OHzS system can save 3.03 kW h when producing 1.0 L of H2 when compared with the N2H4-free seawater system, resulting in energy-saving H2 production. Density functional theory calculations show that the combination of Co-doping and the fabrication of FeCo-Ni2P and MIL-FeCoNi heterointerfaces can result in a low water dissociation barrier, optimized hydrogen adsorption free energy toward HER, and favorable adsorbed dehydrogenation kinetics for HzOR. This processing route paves the way for a practical approach to the efficient utilization of hydrogen, which is abundant in the ocean energy field, to achieve a carbon-neutral hydrogen economy.

Hydrogen and electricity co-generation from hydrazine-assisted water electrolysis on hierarchical porous heteroatoms-doped CoCu catalysts

In order to decrease the electricity consumption of water electrolysis, we investigated a novel hydrazine-assisted water electrolysis for electricity-independent hydrogen production, featuring with lower anodic hydrazine oxidation reaction (HzOR) than cathodic hydrogen evolution reaction (HER). The adsorption and semiconductor characteristics of hierarchical porous CoNS@CuPD, interlacing by Co(OH)2 nanosheets on the Cu dendrites surface, are selectively modified to optimize anodic HzOR and cathodic HER performance through doping B and P heteroatoms, respectively. The working potential of HzOR on B-doped CoNS@CuPD negatively shifts to − 146 mV at 10 mA cm−2, while that of HER on P-doped CoNS@CuPD positively shifts to − 70 mV. Consequently, the hydrazine electrolysis device using B-/P-doped catalysts output a small voltage of 60 mV at 10 mA cm−2, achieving co-generation of hydrogen and electricity for the first time. This work brings an intrinsic break in hydrogen-rich molecule-assisted water electrolysis for hydrogen production.

Ultrathin NiSe Nanosheets on Ni Foam for Efficient and Durable Hydrazine-Assisted Electrolytic Hydrogen Production.

Hydrazine-assisted electrochemical water splitting is an important avenue toward low cost and sustainable hydrogen production. An efficient and stable bifunctional electrocatalyst for the hydrogen evolution reaction (HER) and the anodic hydrazine oxidation reaction (HzOR) is fundamental to this goal. Herein, we employed a facile method to fabricate ultrathin NiSe nanosheet arrays on nickel foam (NiSe/NF), which exhibits predominant electrocatalytic activity for both HER and HzOR. Our investigations revealed that the excellent electrocatalytic activity of the NiSe/NF mainly arises from the abundant electrocatalytic active sites endowed by the ultrathin nanosheet morphology, the rugged feature of the extended (100) nanosheet surface, the rich presence of Se on the nanosheet surface, and the three-dimensional (3D) porous structure of the NF and other factors such as high conductivity of the NiSe/NF and strong NiSe-NF adhesion. We assembled a hydrazine-boosted electrochemical water splitting cell using NiSe/NF as a bifunctional catalyst for both of the electrodes, and the constructed cell exhibits an ultralow overpotential (310 mV at 10 mA cm-2), which is robust for 30 h continuous electrolysis in a 1 M KOH electrolyte. This work provides a promising avenue toward low cost, high-efficiency, and stable hydrogen production based on hydrazine-assisted electrolytic water splitting for future.

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

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.

Anodic hydrazine oxidation assisted hydrogen evolution over bimetallic RhIr mesoporous nanospheres

Bimetallic RhIr mesoporous nanospheres are constructed via a one-step strategy and function well for hydrazine-assisted water splitting.

Fabrication of a porous NiFeP/Ni electrode for highly efficient hydrazine oxidation boosted H2 evolution.

Rational optimization of the surface electronic states and physical structures of non-noble metal nanomaterials is essential to improve their electrocatalytic performance. Herein, we report a facile dual-regulation strategy to fabricate NiFeP/Ni (P-NiFeP/Ni) porous nanoflowers, which involves Fe-doping and creating pores on nanosheets. The as-prepared P-NiFeP/Ni has a hierarchically porous surface, which exposes more electrochemically active sites and dramatically enhances the electron transfer rate. Thus, it exhibits excellent catalytic activity in both anodic hydrazine oxidation reaction (HzOR) and cathodic hydrogen evolution reaction (HER). Interestingly, the coupled electrolysis cell only offers a potential of 0.162 V at 10 mA cm−2 to enable HzOR boosted H2 evolution, highlighting an energy-saving hydrogen evolution strategy.

Synthesis of hollow CoSe2/MoSe2 nanospheres for efficient hydrazine-assisted hydrogen evolution

Hydrazine-assisted hydrogen evolution cell has been regarded as a promising route to replace conventional water splitting because of the lower thermodynamic oxidation potential. Therefore, the design and synthesis of highly efficient bifunctional electrocatalysts for anodic hydrazine oxidation reaction (HzOR) and cathodic hydrogen evolution reaction (HER) are crucial and highly desired. In this work, we report a facile synthesis strategy to prepare hollow CoSe2/MoSe2 nanospheres with abundant active interfaces for hydrazine-assisted hydrogen production. The homogeneous mixing of Co and Mo ions in the metal organic framework precursors ensures the formation of intimately contacted interfaces after selenization, leading to the “reinforced concrete” CoSe2/MoSe2 composites. Benefiting from the CoSe2/MoSe2 interfaces, the hollow CoSe2/MoSe2 nanosphere performs a low HER overpotential of 168 mV with an excellent stability over 12 h. Additionally, it also exhibits a low overpotential of 386 mV (vs. RHE) for HzOR and an ultralow cell voltage (1 mA cm−2) of 160 mV, which are among the best reported performance of powdered electrocatalysts. The present work develops a promising bifunctional electrocatalyst with active interfaces for energy-saving electrolytic hydrogen production.

Bifunctional nanoporous Ni-Zn electrocatalysts with super-aerophobic surface for high-performance hydrazine-assisted hydrogen production

In the present study, an effective approach is proposed to replace the oxygen evolution reaction with the substituted anodic hydrazine oxidation reaction (HzOR) to assist in hydrogen generation based on a bifunctional porous Ni-Zn electrocatalyst with nanosheet arrays. The Ni-Zn catalyst exhibits an extraordinary HzOR performance with a high current density of 970 mA cm−2 at 0.7 V, and 93.8% of its initial activity after 5000 s, simultaneously delivering an overpotential of 68 mV at 10 mA cm−2 for the hydrogen evolution reaction. Moreover, the electrolytic cell is constructed employing Ni-Zn catalysts as both the anode and cathode, achieving 100 mA cm−2 at an ultralow cell voltage of 0.497 V with an outstanding stability over 10 h. The superior electrocatalytic performance can be ascribed to its porous structure with large active surface area, high electrical conductivity, and most importantly the super-aerophobic nature of the Ni-Zn surface. This work also provides a novel approach to designing and constructing porous structured non-noble metal bifunctional electrocatalysts with super-aerophobic surface to be used for energy-saving hydrogen production.

NiCo2O4 nanorod: Synthesis and electrochemical sensing of carcinogenic hydrazine

In this work, we explored a simple hydrothermal process to tune the NiCo2O4 morphology into well defined rod structure with nanoparticle on it. The as prepered NiCo2O4 was characterized by various characterization studies such as XRD, Raman, FT-IR, TGA, FESEM, TEM, XPS and HRTEM. The electrochemical sensing of hydrazine on NiCo2O4 nanorod was examined by cyclic voltammetry and differential pulse voltammetry techniques. The NiCo2O4 shows excellent electrocatalytic performance for the anodic oxidation of hydrazine. Interestingly, NiCo2O4 retain considerable current response after 50 cycles at 25 mV s−1. The Ni and Co in bimetal oxides enhanced the current response due to their electroactive sites. The developed NiCo2O4 not only enhanced the current response of hydrazine but also exhibits good stability. NiCo2O4 demonstrates excellent detection limit and sensitivity of 260 nM and 48.25 µA cm−2 mM−1, respectively. For practical application, NiCo2O4/GCE was used for the sensing of hydrazine in real water samples.

Rhodium phosphide ultrathin nanosheets for hydrazine oxidation boosted electrochemical water splitting

Optimizing component and morphology of precious metal nanomaterials can effectively promote their electrocatalytic performance and expand their application area. In this work, Rh2P ultrathin nanosheets (Rh2P uNSs) with atomic thickness and big surface area are successfully synthesized by phosphating treatment of Rh ultrathin nanosheets (Rh uNSs). Benefiting from special morphology, component, and electronic structure, Rh2P uNSs simultaneously display enhanced electrocatalytic activity for anodic hydrazine oxidation reaction (HzOR) as well as cathodic hydrogen evolution reaction (HER) compared to Rh uNSs in acidic media, which only require at −10 mV and 300 mV potential to obtain 10 mA cm−2 current density for HzOR and HER in three electrode system, respectively. In two electrode system, the symmetric Rh2P uNSs||Rh2P uNSs electrolyzer only requires electrolysis voltage of 0.377 V to achieve 10 mA cm−2 current density for HzOR boosted water splitting in strong acidic media, highlighting an energy-saving electrochemical hydrogen production method.

Anodic Hydrazine Oxidation Assists Energy‐Efficient Hydrogen Evolution over a Bifunctional Cobalt Perselenide Nanosheet Electrode

AbstractWater electrolysis is a promising source of hydrogen; however, technological challenges remain. Intensive efforts have focused on developing highly efficient and earth‐abundant electrocatalysts for water splitting. An effective strategy is proposed, using a bifunctional tubular cobalt perselenide nanosheet electrode, in which the sluggish oxygen evolution reaction is substituted with anodic hydrazine oxidation so as to assist energy‐efficient hydrogen production. Specifically, this electrode produces a current density of 10 mA cm−2 at −84 mV for hydrogen evolution and −17 mV for hydrazine oxidation in 1.0 m KOH and 0.5 m hydrazine electrolyte. An ultralow cell voltage of only 164 mV is required to generate a current density of 10 mA cm−2 for 14 hours of stable water electrolysis.

Anodic Hydrazine Oxidation Assists Energy‐Efficient Hydrogen Evolution over a Bifunctional Cobalt Perselenide Nanosheet Electrode

Water electrolysis is a promising source of hydrogen; however, technological challenges remain. Intensive efforts have focused on developing highly efficient and earth-abundant electrocatalysts for water splitting. An effective strategy is proposed, using a bifunctional tubular cobalt perselenide nanosheet electrode, in which the sluggish oxygen evolution reaction is substituted with anodic hydrazine oxidation so as to assist energy-efficient hydrogen production. Specifically, this electrode produces a current density of 10 mA cm-2 at -84 mV for hydrogen evolution and -17 mV for hydrazine oxidation in 1.0 m KOH and 0.5 m hydrazine electrolyte. An ultralow cell voltage of only 164 mV is required to generate a current density of 10 mA cm-2 for 14 hours of stable water electrolysis.

MnFe2O4@nitrogen-doped reduced graphene oxide nanohybrid: an efficient bifunctional electrocatalyst for anodic hydrazine oxidation and cathodic oxygen reduction

A bifunctional MnFe2O4/N-rGO composite synthesized hydrothermally in a single step is demonstrated for hydrazine oxidation and oxygen reduction.