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 Ni3N‐Co3N 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.
An efficient bifunctional electrocatalyst toward hydrazine‐assisted H2 production was designed by constructing the Ni3N‐Co3N heterointerfaces on Ni foam (Ni3N‐Co3N PNAs/NF). The catalyst can achieve energy‐saving hydrogen production in an overall hydrazine splitting (OHzS) unit, showing its potential for practical applications.
The multimetallic sulfur‐framework catalytic site of biological nitrogenases allows the efficient conversion of dinitrogen (N2) to ammonia (NH3) under ambient conditions. Inspired by biological ...nitrogenases, a bimetallic sulfide material (FeWSx@FeWO4) was synthesized as a highly efficient N2 reduction (NRR) catalyst by sulfur substitution of the surface of FeWO4 nanoparticles. Thus prepared FeWSx@FeWO4 catalysts exhibit a relatively high NH3 production rate of 30.2 ug h−1 mg−1cat 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 15N2‐isotopic labeling experiments. In situ Raman spectra and hydrazine reduction kinetics analysis revealed that the reduction of undissociated hydrazine intermediates (M‐NH2‐NH2) 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.
Inspired by biological nitrogenases, a bimetallic sulfide material (FeWSx@FeWO4) was synthesized for a highly efficient N2 reduction (NRR) catalyst. In situ Raman spectra and hydrazine reduction kinetics analysis revealed that the reduction of undissociated hydrazine intermediates (M‐NH2‐NH2) on the surface of the catalyst is the rate‐determing step for the NRR process.
The role of hydrazine (N2H4) in anammox metabolism has been widely studied; however, studies on N2H4 biosynthesis by anammox bacteria are limited in the literature. In this context, the current ...research aims to investigate the enhancement of biological N2H4 production in the anammox process in a long-term manner. The experimental studies started with the optimization of the operating conditions to achieve maximum N2H4 accumulation. Under favorable conditions (pH = 8.97 ± 0.08; T = 35.5 ± 0.5 °C; initial hydroxylamine dose = 1.46 ± 0.01 mM), 17.16 ± 0.64 mg L−1 of N2H4 accumulated in the batch systems. The continuity of N2H4 bioproduction was then evaluated by long-term observations. A continuous flow bioreactor was operated in four consecutive manipulated periods under optimized conditions. In the long-term operated bioreactor, 55.10 ± 0.30 mg L−1 N2H4 was accumulated at optimal conditions, which was 2.5 times higher than reported in the literature. Although manipulation of the bioreactor operating conditions initially resulted in a significant increase in N2H4 bioaccumulation, it subsequently caused a severe deterioration in anammox activity. However, this could be mitigated by increasing the biomass concentration in the anammox systems. In addition, the relative abundance of Candidatus Kuenenia decreased by 1.88% throughout the long-term operation.
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•Operating conditions were optimized to maximize N2H4 bioaccumulation in the system.•N2H4 accumulation was positively correlated to NH2OH utilization in the system.•N2H4 accumulation increased >1000 times than startup under manipulated conditions.•Continuity of N2H4 accumulation was not observed in long-term operated SBR.•Ca. Kuenenia was the sole anammox genus in the bioreactor throughout the operation.
Ultrafine NiFe nanoparticles (NPs) decorated by La(OH)3 have been successfully prepared via a facile one-step co-reduction method without the help of surfactant or support. It was found that after ...being decorated with La(OH)3, the NiFe–La(OH)3 NPs have a smaller particle size and lower crystallinity. The resultant NiFe–La(OH)3 nanocatalyst exhibits an excellent catalytic activity, 100% H2 selectivity, and satisfied recyclability for hydrogen evolution from hydrous hydrazine (N2H4·H2O) at 343 K under alkaline conditions, giving a high turnover frequency (TOF) value of 100.6 h−1, which is more than 35 times higher than pure NiFe NPs (2.8 h−1). The kinetics study shows that with respect to the concentration of catalyst and N2H4, the N2H4 dehydrogenation reaction follows fist-order kinetics and zero-order kinetics, respectively. Furthermore, NiFe–La(OH)3 also exhibits an outstanding performance and excellent recycle stability during high dehydrogenation of hydrazine borane (N2H4BH3). The excellent performances for the dehydrogenation of N2H4 and N2H4BH3 could be attributed to the strong interaction between La(OH)3 and NiFe NPs, as well as ultrafine and low crystalline NiFe NPs due to the addition of La(OH)3.
NiFe–La(OH)3 nanoparticles have been facilely synthesized by a one-step method, exhibiting much higher catalytic activity and H2 selectivity than that of pure NiFe NPs. Display omitted
•NiFe–La(OH)3 was prepared via a one-step co-reduction method.•The crystallinity and particle size can effectively reduce by addition of La(OH)3.•NiFe–La(OH)3 shows high activity and selectivity for decomposition of N2H4.•TOF value of NiFe–La(OH)3 is 35-fold higher than that of pure NiFe.
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 100 mA cm−2 at an ultralow cell voltage of 54 mV and a high current density of 853 mA cm−2 at a cell voltage of 0.6 V. The RhRu0.5 electrocatalysts further demonstrate a stable operation at a high current density of 100 mA cm−2 for 80 hours of testing period with little irreversible degradation. The overall performance greatly exceeds that of the previously reported hydrazine‐assisted water electrolyzers, offering a pathway for efficiently converting hazardous hydrazine into molecular hydrogen.
Bifunctional ultrathin RhRu0.5‐alloy wavy nanowire electrocatalysts are designed and synthesized via a facile solvothermal method, demonstrating excellent performance for the hydrazine oxidation reaction (HzOR) and hydrogen evolution reaction (HER), and offering an attractive electrocatalyst system for hydrazine‐assisted water electrolysis without ammonia as a byproduct.
It is highly attractive but challenging to develop earth‐abundant electrocatalysts for energy‐saving electrolytic hydrogen generation. Herein, we report that Ni2P nanoarrays grown in situ on nickel ...foam (Ni2P/NF) behave as a durable high‐performance non‐noble‐metal electrocatalyst for hydrazine oxidation reaction (HzOR) in alkaline media. The replacement of the sluggish anodic oxygen evolution reaction with such the more thermodynamically favorable HzOR enables energy‐saving electrochemical hydrogen production with the use of Ni2P/NF as a bifunctional catalyst for anodic HzOR and cathodic hydrogen evolution reaction. When operated at room temperature, this two‐electrode electrolytic system drives 500 mA cm−2 at a cell voltage as low as 1.0 V with strong long‐term electrochemical durability and 100 % Faradaic efficiency for hydrogen evolution in 1.0 m KOH aqueous solution with 0.5 m hydrazine.
A Ni2P nanoarray grown on nickel foam (Ni2P/NF) behaves as a bifunctional catalyst for anodic hydrazine oxidation and cathodic hydrogen evolution in alkaline hydrazine solution. This two‐electrode electrolytic system drives 500 mA cm−2 at a cell voltage as low as 1.0 V with strong long‐term electrochemical durability and 100 % Faradaic efficiency for hydrogen evolution.
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.
Sweet electrocatalytic synergy: An effective strategy for energy‐saving water electrolysis is presented. The sluggish oxygen evolution reaction is replaced by anodic hydrazine oxidation on a low‐cost and bifunctional cobalt perselenide electrode.
Cage like CuFe.sub.2O.sub.4 hollow nanostructure has been synthesized successfully using hard template method under the hydrothermal condition. Cu(NO.sub.3).sub.2·6H.sub.2O, ...Fe(NO.sub.3).sub.2·9H.sub.2O and glucose were dissolved in water, and the mixture was heated to 180 °C in an autoclave. The removal of carbon was achieved by calcination at 800 °C and finally, the cage like CuFe.sub.2O.sub.4 hollow structure was obtained. This cage like CuFe.sub.2O.sub.4 hollow structure was characterized by FE-SEM, EDS, TEM and XRD. The catalytic performance of this hollow nanostructure was evaluated for the synthesis of bis pyrazol-5-ols. To this end, the one pot condensation reactions of phenylhydrazine, ethyl acetoacetate and different aromatic aldehyde at 80 °C under the solvent free condition were performed. The optimum amount of applied catalyst for this transformation was obtained to be 0.04 mol %. Noteworthy, catalyst was easily recoverable and was reused for 7 times with the remaining of its initial structure as well as its catalytic activity. Graphical Cage like CuFe.sub.2O.sub.4 hollow nanostructure are stably and efficiently attainable for conversion of precursors to 4,4'-(aryl methylene)bis(3-methyl-1H-pyrazol-5-ol)s
Cage like CuFe.sub.2O.sub.4 hollow nanostructure has been synthesized successfully using hard template method under the hydrothermal condition. Cu(NO.sub.3).sub.2·6H.sub.2O, ...Fe(NO.sub.3).sub.2·9H.sub.2O and glucose were dissolved in water, and the mixture was heated to 180 °C in an autoclave. The removal of carbon was achieved by calcination at 800 °C and finally, the cage like CuFe.sub.2O.sub.4 hollow structure was obtained. This cage like CuFe.sub.2O.sub.4 hollow structure was characterized by FE-SEM, EDS, TEM and XRD. The catalytic performance of this hollow nanostructure was evaluated for the synthesis of bis pyrazol-5-ols. To this end, the one pot condensation reactions of phenylhydrazine, ethyl acetoacetate and different aromatic aldehyde at 80 °C under the solvent free condition were performed. The optimum amount of applied catalyst for this transformation was obtained to be 0.04 mol %. Noteworthy, catalyst was easily recoverable and was reused for 7 times with the remaining of its initial structure as well as its catalytic activity.
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