Oxidation Of Hydrazine Research Articles

Clinically Applicable Homogeneous Assay for Serological Diagnosis of Alpha-Fetoprotein by Impact Electrochemistry.

Tumor protein quantification with high specificity, sensitivity, and efficiency is of great significance to enable early diagnosis and effective treatment. The existing methods for protein analysis usually suffer from high cost, time-consuming operation, and insufficient sensitivity, making them not clinically friendly. In this work, a label-free homogeneous sensor based on the nano-impact electroanalytic (NIE) technique was proposed for the detection of tumor protein marker alpha-fetoprotein (AFP). The detection principle is based on the recovery of current of single PtNP catalyzed hydrazine oxidation due to the release of the pre-adsorbed passivating aptamers on PtNPs from the competition of the stronger binding between the specific interaction of the AFP aptamer and AFP. The intrinsic one-by-one analytical ability of NIE allows highly sensitive detection, which can be further improved by reducing the reaction/incubation volume. Meanwhile, the current sensor avoids a laborious labeling procedure as well as the separation and washing steps due to the in situ characteristic of NIE. Accordingly, the current sensor enables efficient, highly sensitive, and specific AFP analysis. More importantly, the reliable detection of AFP in diluted real sera from hepatocellular carcinoma (HCC) patients is successfully achieved, indicating that the impact electrochemistry-based sensing platform has great potential to be applied in point-of-care devices for HCC liquid biopsy.

Regulating electronic structure by Mn doping for nickel cobalt hydroxide nanosheets/carbon nanotube to promote oxygen evolution reaction and oxidation of urea and hydrazine

Electrocatalytic water splitting is one of the direct and efficient means to yield high-purity hydrogen, but it still exists some challenges in addition to the sluggish anodic oxygen evolution reaction (OER). Constructing highly-efficient electrocatalysts with superior properties plays an essential role in industrial hydrogen production. In this work, a novel electrocatalyst with a distinctive three-dimensional (3D) structure is constructed by intertwining two-dimensional (2D) hexagonal NiCo hydroxide nanosheets (NiCo HNS) with one-dimensional (1D) carbon nanotubes (CNTs). The strategy of elemental doping engineering is employed to further enhance the catalytic performance. The as-fabricated composite of Mn-doped nickel cobalt hydroxide nanosheets intertwined with CNTs (1.5Mn-NiCo HNS/CNT) delivers superior OER electrocatalytic performance, which requires an overpotential of only 239 mV to achieve the current density of 10 mA cm−2 in 1 M KOH. Compared to NiCo HNS/CNT, the 1.5Mn-NiCo HNS/CNT electrocatalyst exhibits characteristics of improved electrical conductivity, larger electrochemical active surface area (ECSA), and faster reaction kinetics due to Mn doping. Density functional theory (DFT) calculations revealed that the adsorption of OH– during the first step of OER process was the potential determining step for the Mn substituted Co sites, and the Mn substituted Co sites were the optimum reactive sites that determined the OER performance of the 1.5Mn-NiCo HNS/CNT. Mn doping was proved beneficial to optimize the reaction path and decrease the reaction kinetics energy barrier. The addition of urea or hydrazine into the electrolyte directly decreases the energy consumption and realize their decomposition as pollutants in industrial and agricultural wastewater.

Electrochemical sensor amplified with cellulose nanofibers/Fe3O4 composite to the monitoring of hydrazine as a pollutant in water and wastewater samples

A quite swift and sensitive analytical instrument was designed in this work to detect and monitor hydrazine in various water and wastewater samples. The glassy carbon electrode (GCE) was amplified using cellulose nanofibers/Fe3O4 composite (CNF–Fe3O4/NC) for monitoring hydrazine in the concentration range of 0.001 - 140 M with a superior detection limit of 0.5 nM. Results showed a diffusion control process for the oxidation of hydrazine at the surface of CNF–Fe3O4/NC/GCE. Under the optimum condition (pH=8.0), the oxidation current of hydrazine was improved by about 2.3 times and the oxidation potential was reduced by about 60 mV at the surface of CNF–Fe3O4/NC/GCE compare to unmodified GCE. A standard addition method was employed to assess CNF–Fe3O4/NC/GCE's capability for the detection of hydrazine in water and wastewater samples, and a recovery range of 97.6 % to 104.9 % was noted.

Electrocatalytic Behavior of Manganese and Cobalt Porphyrins Attached to Graphene Quantum Dots: Applied in the Oxidation of Hydrazine

AbstractManganese and cobalt metalated 5, 10, 15‐tris(aminophenyl)‐20‐(4‐carboxyphenyl) porphyrins (ClMnTA3CPP and CoTA3CPP) were synthesized and attached to graphene quantum dots (GQDs) via π‐π interaction and electrostatic interaction. The electrochemical oxidation of hydrazine was performed via cyclic voltammetry and chronoamperometry. The CoTA3CPP showed good electrocatalytic activity towards the oxidation of hydrazine in terms of catalytic rate constants and limits of detection (LoD). ClMnTA3CPP showed lower overpotential 0.60 V. The introduction of GQDs improved the electrocatalytic ability when combined with CoTA3CPP and ClMnTA3CPP with the lowest LoD (0.0025 mM CoTA3CPP–GQDs) followed by ClMnTA3CPP–GQDs with 0.0033 mM.

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.

Regulating electronic structure of porous nickel nitride nanosheet arrays by cerium doping for energy-saving hydrogen production coupling hydrazine oxidation

Regulating electronic structure of porous nickel nitride nanosheet arrays by cerium doping for energy-saving hydrogen production coupling hydrazine oxidation

Tuning the size and chemisorption of FeP4 by trace Ru doping for hydrazine-assisted hydrogen evolution in seawater at large‐current‐density

Integrating thermodynamically favorable hydrazine oxidation reactions (HzOR) with seawater electrolysis will avoid chlorine evolution reaction (ClER) and realize decoupled hydrogen evolution. Herein, the self-supporting Ru-doped FeP4 nanosheets (Ru-FeP4/IF) grown on iron foam are successfully constructed as bifunctional electrocatalysts to facilitate H2 production and HzOR simultaneously. Benefiting from trace Ru doping tuning the size and chemisorption of FeP4, the as-prepared Ru-FeP4/IF requires low potential of 318.0 mV and 335.0 mV to drive 1000 mA cm−2 for HER and HzOR in alkaline seawater, respectively. Notably, only an ultralow voltage of 0.90 V is required to reach 1000 mA cm−2 with outstanding long-term stability and 100% Faradaic efficiency when Ru-FeP4/IF is assembled in a two-electrode cell for overall hydrazine splitting (OHzS). Density functional theory (DFT) calculations show that Ru-doped modulates electronic structure to optimize adsorption free energy of H* (ΔGH*) for HER and decrease dehydrogenation of *N2H4 to *N2H3 for HzOR on FeP4.

Constructing Three‐Phase Heterojunction with 1D/3D Hierarchical Structure as Efficient Trifunctional Electrocatalyst in Alkaline Seawater

AbstractRational design of highly efficient, robust, and low‐cost trifunctional electrocatalysts for oxygen reduction reaction (ORR), hydrazine oxidation reaction (HzOR), and hydrogen evolution reaction (HER) is extremely urgent for seawater‐based renewable energy conversion and storage, including direct hydrazine fuel cells (DHzFC) and overall hydrazine splitting (OHzS). Herein, FeP/FeNi2P encapsulated in N, P co‐doped hierarchical carbon (FeNiP‐NPHC) in situ grown on nickel foam is fabricated via a hydrothermal‐pyrolysis‐phosphidation procedure. Benefiting from the strong coupling effect among FeP, FeNi2P, and N, P co‐doped carbon at the three‐phase heterojunction interface, as well as the unique 1D/3D hierarchical structure, the as‐prepared FeNiP‐NPHC shows superior ORR (E1/2 = 0.83 V), HzOR (E100 = 7 mV), and HER (E100 = ‐180 mV) performance in alkaline seawater. Density functional theory functions indicate that constructing three‐phase heterojunction interface of FeNiP‐NPHC can effectively adjust the d‐band center and electronic structure, which is conductive to balance and optimize the trifunctional electrocatalytic performance. As proof of concept, the self‐assembled DHzFC is utilized to power the OHzS in alkaline seawater successfully, verifying application potential of the FeNiP‐NPHC as trifunctional electrocatalyst.

Covalent Organic Frameworks-TpPa-1 as an Emerging Platform for Electrochemical Sensing.

Covalent organic frameworks (COFs) are a new type of metal-free porous architecture with a well-designed pore structure and high stability. Here an efficient electrochemical sensing platform was demonstrated based on COFs TpPa-1 constructed by 1,3,5-triformylphloroglucinol (Tp) with p-phenylenediamine (Pa-1), which possesses abundant nitrogen and oxo-functionalities. COFs TpPa-1 exhibited good water dispersibility and strong adsorption affinities for Pd2+ and thus was used as loading support to modify Pd2+. The Pd2+-modified COFs TpPa-1 electrode (Pd2+/COFs) showed high electrocatalytic activity for both hydrazine oxidation reaction and nitrophenol reduction reaction. In addition, TpPa-1-derived nitrogen-doped carbon presented high activity for the electro-oxidation of reduced glutathione (GSH), and sensitive electrochemical detection of GSH was achieved. The presented COFs TpPa-1 can be utilized as a precursor as well as support for anchoring electro-active molecules and nanoparticles, which will be useful for electrochemical sensing and electrocatalysis.

Metal doping and Hetero-engineering of Cu-doped CoFe/Co embedded in N-doped carbon for improving trifunctional electrocatalytic activity in alkaline seawater

The development of high-performance and robust electrocatalyst suitable for oxygen reduction reaction (ORR), hydrazine oxidation reaction (HzOR), and hydrogen evolution reaction (HER) in seawater still faces huge challenges. In this study, Cu-doped CoFe/Co encapsulated by N-doped carbon (Cu-CoFe/Co/NC) is synthesized via chemical precipitation followed by carbonization method, in which the electronic structure and d-band center of Cu-CoFe/Co/NC are regulated by metal doping and hetero-engineering. The as-synthesized Cu-CoFe/Co/NC exhibit excellent electrocatalytic activity for ORR (E1/2 = 0.87 V), HzOR (η10 = 281 mV), and HER (η-10 = 217 mV) in alkaline seawater. Inspiringly, the self-assembled direct hydrazine fuel cell (DHzFC) are used to power overall hydrazine splitting (OHzS) for proof of concept, demonstrating the great potential of Cu-CoFe/Co/NC as trifunctional electrocatalyst toward energy storage and conversion devices.

Size Sensitivity of Supported Palladium Species on Layered Double Hydroxides for the Electro-oxidation Dehydrogenation of Hydrazine: From Nanoparticles to Nanoclusters and Single Atoms

The hydrazine oxidation reaction (HzOR) is structure-sensitive, and a slight modification of the catalyst structure can generate a significant change in activity. To date, no study on the size effect of the catalyst at a subnanometer scale on HzOR has been reported yet. Herein, we report the fabrication of Pd species with sizes ranging from nanoparticles (NPs) and nanoclusters (NCs) to single atoms (SAs) onto a NiFe-layered double hydroxide by fine-tuning precursors and reduction methods. When applied for the electro-oxidation dehydrogenation of hydrazine, the as-prepared Pd NCs/NiFe exhibit a current density of 4.3 A mgPd–1 at 0.35 V versus RHE. It should be noted that the mass activity of Pd NCs/NiFe was 36 times that of Pd SAs/NiFe and 7 times that of Pd NPs/NiFe, respectively. The in situ electrochemical impedance spectroscopy and density functional theory calculation demonstrate that different from previous studies, both the Pd SAs/NiFe and Pd NPs/NiFe are suboptimal in HzOR due to the isolated active sites of the Pd SAs/NiFe and large steric hindrance of Pd NPs/NiFe, respectively. Instead, the strong intracluster interactions of Pd NCs/NiFe lift the d-band center closer to the Fermi level, leading to stronger hybridization of Pd d-orbitals and the σ orbitals of N2H4 molecules. Consequently, the excellent performance of Pd NCs/NiFe can be attributed to its multiple neighboring metal sites, high d-band center, and small steric hindrance.

Corrosion inhibition of hydrazine on carbon steel in water solutions with different pH adjusted by ammonia

Abstract The ammonia-hydrazine shutdown protection method is widely used in thermal power plants in China because of its good protective performance. However, the toxicity and safety of hydrazine have restricted its use in many power plants, and it is necessary to improve the shutdown protection techniques. In this paper, electrochemical impedance spectroscopy and potentiodynamic polarization curves were used to study the effect of hydrazine in water solutions of different pH values, adjusted with ammonia on the corrosion behavior of carbon steel. It was found that in the water solution without hydrazine, the corrosion resistance of a carbon steel electrode increased with raising the pH. When the pH value of water increased to 10.5, the impedance value of the carbon steel increased significantly, the corrosion current density decreased from 26.06 μA·cm−2 at pH 10.0 to 2.36 μA·cm−2, and the steel surface was passivated. Hydrazine had different effects on the electrochemical corrosion behavior of carbon steel in water solutions with various pH. When the pH of water was not higher than 10.0, hydrazine had a good corrosion inhibition effect on carbon steel. When the pH of water was not lower than 10.5, the addition of hydrazine inhibited the passivation of carbon steel and promoted the corrosion. The adsorption and substitutional oxidation of hydrazine in the anode region of carbon steel surface should be the reasons for the above phenomenon.

Vacancy-Rich MXene-Immobilized Ni Single Atoms as a High-Performance Electrocatalyst for the Hydrazine Oxidation Reaction.

Single-atom catalysts (SACs), on account of their outstanding catalytic potential, are currently emergingas high-performance materials in the field of heterogeneous catalysis. Constructing a strong interaction between the single atom and its supporting matrix plays a pivotal role. Herein, Ti3 C2 Tx -MXene-supported Ni SACs are reported by using a self-reduction strategy via the assistance of rich Ti vacancies on the Ti3 C2 Tx MXene surface, which act as the trap and anchor sites for individual Ni atoms. The constructed Ni SACs supported by the Ti3 C2 Tx MXene (Ni SACs/Ti3 C2 Tx ) show an ultralow onset potential of -0.03 V (vs reversible hydrogen electrode (RHE)) and an exceptional operational stability toward the hydrazine oxidation reaction (HzOR). Density functional theory calculations suggest a strong coupling of the Ni single atoms and theirsurrounding C atoms, which optimizes the electronic density of states, increasing the adsorption energy and decreasing the reaction activation energy, thus boosting the electrochemical activity. The results presented here will encourage a wider pursuit of 2D-materials-supported SACs designed by a vacancy-trapping strategy.

Meta-Omics reveal the metabolic acclimation of freshwater anammox bacteria for saline wastewater treatment

Abstract Saline wastewater is a big challenge for the application of anammox processes. Although the feasibility of freshwater anammox bacteria for saline wastewater treatment was revealed, its metabolic acclimation to different saline concentrations is still elusive. Here, one low-strength-fed anammox reactor was operated with the shift of saline concentrations. The results showed that one Ca. Brocadia genome with a relative abundance of 31.5% was recovered. Meta-Omics analyses showed that salinity (around 12.5 g L −1 NaCl) could promote the nitrogen transformation in Ca. Brocadia through the driven of dissimilatory nitrate reduction to ammonium (DNRA). Specific sodium translocations pump (Na + -NADH:quinone oxidoreductase), as well as more genes associated with H + - dependent membrane-bound ATP formation and Na + -dependent membrane-bound ATP formation, was highly expressed in Ca. Brocadia under saline conditions than that under fresh conditions. This implied that such Na + transduction was likely associated with the NADPH/NADH via the hydrazine oxidation pathway. Notably, sodium extrusion was also associated with energy exploitation from the hydrolysis of pyrophosphatase (PPi) through K + -stimulated pyrophosphate-energized sodium pump. This study shed light on the metabolic acclimation, such as nitrogen transformation and cation-induced energy transduction (i.e., Na + , K + , and Ca 2+ ) in Ca. Brocadia, illustrating their feasibility for saline and freshwater wastewater treatment. • Ca. Brocadia AMX1 with low similar (<81.8%) to published strains was enriched. • Salinity of 12.5 g L −1 NaCl promoted nitrogen transformation in Ca. Brocadia AMX1 . • The cation-induced energy transductions are verified in Ca. Brocadia AMX1 . • The hydrolysis of pyrophosphatase (PPi) can provide energy for sodium extrusion. • Metabolic linkage of nitrogen conversion and cations transductions were discussed.

(Keynote) Interpretation of Oxygen Reduction Activity Volcano Correlations for MN4 Molecular Catalysts Compared to Those for Metallic Electrodes

A classical well-known reactivity index in electrocatalysis is the binding energy of key intermediates to the active sites. For example, this is well documented for the catalytic activity of metal electrodes for the oxygen reduction reaction (ORR)[1], alloys and metal oxides and less studied for molecular catalysts [2]. The activity at constant potential (log(i)E) plotted versus the M-O2 binding energy has the shape of a volcano. This is well documented in several papers, especially by the group of Norksov for metallic electrodes [1] and can be applied to many electrochemical reactions. This has been extended to MN4 molecular catalysts. In contrast to metallic electrodes MN4 molecular catalysts have discrete energy levels and the active site is the central metal, surrounded by an organic ligand with an MN4 central moiety. Essentially one of the key intermediates is the binding of the reacting O2 molecule to the active sites at the rate determining step as: [MN4]ad + O2(aq) + e- ↔ [RMN4O2 -]ad where MN4 is a surface confined macrocyclic complex or a pyrolyzed catalysts bearing a MN4 active moiety embedded in a graphene or graphitic structure. As the ORR reaction involves the transfer of several electrons ( 2, 2+2 or 4 electrons), several adsorbed intermediates can be involved. If the controlling step is the first step, it is expected that for the binding step when DGad = 0 a maximum activity should be observed and the partial coverage of adsorbed intermediate is = 0.5. On thermodynamic ground this corresponds to a thermoneutral condition for the best catalyst. In this work we have tested this hypothesis by studying ORR in alkaline media using several iron porphyrins and iron phthalocyanines as catalysts immobilized on graphite and carbon nanotubes. The trends in reactivity versus the Fe(III)/(II) redox potential for ORR describe a typical volcano correlation. However if the currents are divided by the θFe(II), the fraction of active sites calculated at E=-0.24 V vs SCE using the Nernst equation, log(i/ θFe(II),)E vs. E°Fe(III)/(II) gives a straight line of slope -0.120V/decade. The maximum corresponds to θFe(II) = 0.5 and occurs at a potential close to that used for comparing the activities. A similar behaviour is observed for the oxidation of hydrazine but the continuation of the straight line is observed at potentials more positive than that of the maximum. Again the maximum is observed at the potential chosen for comparison. Those catalysts having Eº’ Fe(III)/(II) >> θFe(II) higher than -0.56V (for hydrazine oxidation) are in the Fe(III) state as predicted by the Nernst equation. That oxidation state Fe(III) is inactive for both reactions studied as OH- ions are strongly bound to Fe(III), especially in alkaline media. So the falling of the activities in the strong binding side of the volcano can be attributed preferentially to a gradual decline in the number of Fe(II) active sites and not to gradual decrease of the fraction (1-θ ) of empty or available active sites due to occupancy by intermediates. Schmickler and Santos [3] have shown that some volcano correlations for HER on metals that are in an oxidized form, and then inactive for this reason.We conclude that even though there are similarities between the volcano correlations for metallic and molecular catalysts, there some differences in the interpretation of the activity maximum that might not correspond to a thermoneutral condition. Acknowledgements: This work was supported by ANID, Anillo Project ACT 192175 and Fondecyt, Project 1181037

Reduction-induced interface reconstruction to fabricate MoNi4-based hollow nanorods for hydrazine oxidation assisted energy-saving hydrogen production in seawater

Reduction-induced interface reconstruction to fabricate MoNi4-based hollow nanorods for hydrazine oxidation assisted energy-saving hydrogen production in seawater

Self-supported iron-doped nickel sulfide as efficient catalyst for electrochemical urea and hydrazine oxidation reactions

The electrochemical oxidation of urea and hydrazine over self-supported Fe-doped Ni3S2/NF (Fe–Ni3S2/NF) nanostructured material is presented. Among the various reaction conditions Fe–Ni3S2/NF-2 prepared at 160 °C for 8 h using 0.03 mM Fe(NO3)3 shows the best results for the hydrazine and urea oxidation reactions. The potential values of 0.36, 1.39, and 1.59 V are required to achieve the current density of the 100 mA cm−2 in 1 M hydrazine (Hz), 0.33 M urea, and 1 M KOH electrolyte, respectively. The onset potential in 1 M KOH, 0.33 M Urea +1 M KOH, and 1 M Hz + 1 M KOH values are 1.528, 1.306, and 0.176 respectively. The Fe–Ni3S2/NF-2 shows stable performance at 10 mA cm−2 until 50 h and at 60 mA cm−2 over the 25 h. A cell of PtC//Fe–Ni3S2/NF-2 requires the potential of 0.49, 1.46, and 1.59 V for the hydrogen production in 1 M Hz + 1 M KOH, 0.33 M Urea +1 M KOH, and 1 M KOH electrolyte, respectively, at a current density of 10 mA cm−2, and almost 90% stable for the hydrogen production over the 80 h in all electrolytes. The improvement of the chemical kinetics of urea and hydrazine oxidation is due to the synergistic effect of the adsorption and fast electron transfer reaction on Fe–Ni3S2/NF-2. The doped Fe ion facilitates the fast electron transfer and the surface of Ni3S2 support to the urea and hydrazine molecule adsorption.

Magic hybrid structure as multifunctional electrocatalyst surpassing benchmark Pt/C enables practical hydrazine fuel cell integrated with energy-saving H2 production

A hybrid catalyst structure can provide abundant active sites and tailored electronic properties, but the major challenge lies in achieving delicate control over its composition and architecture to improve the catalytic activity toward different electrochemical reactions simultaneously. Herein, we present the rational design of a magic hybrid structure with low Pt loading (5.90 ​wt%), composed of CoPt3 and CoPt nanoparticles supported on N-doped carbon (CoPt3/CoPt⊂PLNC). Importantly, it shows superior multifunctional catalytic activity in alkaline conditions, requiring a low overpotential of 341 and 20 ​mV to achieve 10 ​mA ​cm−2 for the hydrazine oxidation reaction (HzOR)/hydrogen evolution reaction (HER), respectively, and it delivers a half-wave potential of 0.847 ​V for the oxygen reduction reaction (ORR). Theoretical calculations reveal that the metal–carbon hybrid modulates kinetic behavior and induces electron redistribution, achieving the energetic requirements for multiple electrocatalysis. We demonstrate sustainable H2 production utilizing solely the CoPt3/CoPt⊂PLNC catalyst, without external electric power input, suggesting its inspiring practical utility.

Robust Ru-N metal-support interaction to promote self-powered H2 production assisted by hydrazine oxidation

Electrocatalytic overall water splitting is hailed as the most promising approach to sustainably produce hydrogen on big scale, but the sluggish anodic oxygen evolution reaction (OER) with large operating potential results in the enormous energy consumption. To couple the cathodic hydrogen evolution reaction (HER) with low-potential hydrazine oxidation reaction (HzOR) is highly promising to significantly reduce the input cell voltage of water electrolysis, which requires high-performance bifunctional HER and HzOR electrocatalysts. Herein, a new-type Ru nanoparticle/mesoporous N-doped carbon (Ru/MPNC) composite is readily constructed with greatly exposed ultrafine Ru particles fused into N-doped carbon walls, and stabilized by in situ formed robust Ru-N metal-support interaction inherently stemming from the particular precursor, thus exhibiting superior bifunctional HER and HzOR activity, far surpassing commercial Pt/C. Furthermore, the two-electrode electrolyzer only require an ultrasmall cell voltage of 0.149 V to achieve 50 mA cm-2, which can be also easily driven by a direct hydrazine-H2O2 fuel cell to attain a decent H2 production rate of 0.893 mmol h−1. The theoretical calculations uncover the robust integration of Ru with NC can tailor the electronic property of exposed Ru sites, endowing the decreased water dissociation energy barrier, together with optimized adsorption free energies of H* and dehydrogenation intermediates of N2H4.

Architecting the AuPt alloys for hydrazine oxidation as an anolyte in fuel cell: Comparative analysis of hydrazine splitting and water splitting for energy-saving H2 generation

Replacing the kinetically sluggish anodic oxygen evolution reaction (OER) with hydrazine (N2H4) oxidation reaction (HzOR) could be the effective approach for achieving energy-saving hydrogen (H2) fuel production in a water electrolyzer system. Thus, developing the efficient HzOR electrocatalysts, combined with the cathodic H2 evolution reaction (HER) is of vital importance for the high-rate H2 fuel generation as well as for the advancement of a N2H4 fuel cell. Herein, we utilized a facile integrated process of pulsed laser irradiation and sonochemical process to synthesize AuPt alloys by the irradiation of laser to a mixture of Au/Pt solution in methanol/DI water in varied proportions. The AuPt alloy plays a key role in the chemisorption of N2H4 on its surface, forming a dative bond involving electrons of the lone pair of nitrogen in N2H4 and empty orbitals of Pt in the alloy, indicating its high intrinsic activity against HzOR. The optimal composition of Au1Pt8 electrode demonstrates outstanding characteristics of HER with an ultralow overpotential of 26 mV at 10 mA cm−2 in alkaline medium while requiring 502 mV to attain 10 mA cm−2 for HzOR in 0.5 M N2H4/1.0 M KOH electrolyte. In addition, the assembled overall N2H4 splitting electrolyzer cell using Au1Pt8 alloys as both anode and cathode requires cell voltage of only ~0.172 V at 10 mA cm−2 with tremendous stability over 10 h, which is much lower than the voltage of 1.773 V required for the overall water splitting electrolyzer. The present study validates the feasibility of AuPt alloys for stimulating N2H4 fuel cells in the future to achieve both electrical energy generation and high-rate H2 fuel production.