Hydrazine Oxidation Reaction Research Articles

1D/3D Heterogeneous Assembling Body of Cobalt Nitrides for Highly Efficient Overall Hydrazine Splitting and Supercapacitors.

Herein, the construction of a heterostructured 1D/3D CoN-Co2 N@NF (nickel foam) electrode used for thermodynamically favorable hydrazine oxidation reaction (HzOR), as an alternative to sluggish anodic oxygen evolution reaction (OER) in water splitting for hydrogen production, is reported. The electrode exhibits remarkable catalytic activities, with an onset potential of -0.11V in HzOR and -71mV for a current density of 10mA cm-2 in hydrogen evolution reaction (HER). Consequently, an extraordinary low cell voltage of 53mV is required to achieve 10mA cm-2 for overall hydrazine splitting in a two-electrode system, demonstrating significant energy-saving advantages over conventional water splitting. The HzOR proceeds through the 4e- reaction pathway to release N2 while the 1e- pathway to emit NH3 is uncompetitive, as evidenced by differential electrochemical mass spectrometric measurements. The X-ray absorption spectroscopy, in situ Raman spectroscopy, and theoretical calculations identify cobalt nitrides rather than corresponding oxides/(oxy)hydroxides as catalytic species for HzOR and illustrate advantages of heterostructured CoN-Co2 N in optimizing adsorption energies of intermediates/reagents and promoting catalytic activities toward both HzOR and HER. The CoN-Co2 N@NF is also an excellent supercapacitive material, exhibiting an increased specific capacity (938 F g-1 at 1 A g-1 ) with excellent cycling stability (95.8%, 5000 cycles).

Unveiling the origin of activity in RuCoOx-anchored nitrogen-doped carbon electrocatalyst for high-efficiency hydrogen production and hydrazine oxidation using Raman spectroscopy

Hydrazine-assisted water electrolysis has gained much attention nowadays as an energy-saving strategy for the large-scale production of hydrogen fuel. Regardless, the synthesis of highly proficient bifunctional electrocatalysts remains a major challenge. Metal–organic frameworks (MOF) derived electrocatalysts have recently demonstrated excellent bifunctional activity in water electrolysis. Herein, we developed a new type of Ru-MOF on rod-like Co-MOF (Ru/Co-MOF) microstructures via a two-step solvothermal route. Subsequently, the Ru/Co-MOF was used as a precursor and self-template to synthesize an electrocatalytically active RuO2/Co3O4 anchored nitrogen-doped carbon (RuCoOx@NC) composite via a one-pot pyrolysis–oxidation strategy under atmospheric air. The RuCoOx@NC composite showed an ultralow overpotential of 44 mV for the hydrogen evolution reaction and 255 mV for the oxygen evolution reaction at 10 mA cm−2 in a 1 M KOH solution. Besides, the RuCoOx@NC composite exhibited an ultra-small working potential of − 0.040 V (vs. reversible hydrogen electrode (RHE)) for the hydrazine oxidation reaction at 10 mA cm−2 in a 1 M KOH/0.5 M hydrazine solution. The assembled RuCoOx@NC∥RuCoOx@NC membrane-free overall hydrazine splitting electrolyzer only required ultralow cell voltages of 0.063 and 0.505 V to produce 10 and 100 mA cm−2, with remarkable long-term stability, demonstrating its exceptional bifunctional activity. Ex situ Raman spectroscopy results indicate that both Co3O4 and RuO2 species contribute to the electrocatalytic activity of the RuCoOx@NC composite. This work suggests a potential strategy for developing bifunctional electrocatalytic materials for energy-saving hydrogen production to solve future energy demands.

Boosting electrocatalytic hydrazine oxidation at single-crystalline Ni nanosheets with embedded NiZn

Hydrazine oxidation reaction (HzOR) plays a crucial role in direct hydrazine fuel cells and holds promise for replacing the kinetics-sluggish oxygen evolution reaction in splitting water. While Ni–Zn alloys exhibit exceptional activity for HzOR, their synthesis under mild conditions remains a challenge. Herein, a Ni–Zn nanosheet catalyst with NiZn inclusion was prepared on Ni foam by controllable chemical etching together with ethylene glycol reduction. X-ray diffraction and transmission electron microscopy confirmed the single-crystalline nature and the presence of intermetallic NiZn. The strong interaction between Ni and ZnO, along with defects, facilitated the formation of this intermetallic compound. The Ni–Zn/Ni foam exhibits remarkable catalytic activity (214.3 ​mA ​cm−2 at 0.1 ​V) and durability (87.8 ​% retention after 24 ​h) towards hydrazine electrooxidation, thanks to the combined benefits of intermetallic NiZn, mesoporous nanosheets, microscopic defects, single-crystalline characteristics, and a coherent Ni–NiZn interface. This study provides a new method for designing highly active Ni–Zn electrocatalysts for HzOR.

Hydrazine-Assisted Acidic Water Splitting Driven by Iridium Single Atoms.

Water splitting, an efficient technology to produce purified hydrogen, normally requires high cell voltage (>1.5V), which restricts the application of single atoms electrocatalyst in water oxidation due to the inferior stability, especially in acidic environment. Substitution of anodic oxygen evolution reaction (OER) with hydrazine oxidation reaction (HzOR) effectually reduces the overall voltage. In this work, the utilization of iridium single atom (Ir-SA/NC) as robust hydrogen evolution reaction (HER) and HzOR electrocatalyst in 0.5m H2 SO4 electrolyte is reported. Mass activity of Ir-SA/NC is as high as 37.02 A mgIr -1 at overpotential of 50mV in HER catalysis, boosted by 127-time than Pt/C. Besides, Ir-SA/NC requires only 0.39V versus RHE to attain 10mA cm-2 in HzOR catalysis, dramatically lower than OER (1.5V versus RHE); importantly, a superior stability is achieved in HzOR. Moreover, the mass activity at 0.5V versus RHE is enhanced by 83-fold than Pt/C. The in situ Raman spectroscopy investigation suggests the HzOR pathway follows *N2 H4 →*2NH2 →*2NH→2N→*N2 →N2 for Ir-SA/NC. The hydrazine assisted water splitting demands only 0.39V to drive, 1.25V lower than acidic water splitting.

Versatile, Stable, and Scalable Gel‐Like Aerophobic Surface System (GLASS) for Hydrogen Production

AbstractFacile removal of adsorbed gas bubbles from electrode surfaces is crucial to realize efficient and stable energy conversion devices based on electrochemical gas evolution reactions. Conventional studies on bubble removal have limited applicability and scalability due to their reliance on complex and energy/time‐intensive processes. In this study, a simple and versatile method is reported to fabricate large‐area superaerophobic electrodes (up to 100 cm2) for diverse gas evolution reactions using the gel‐like aerophobic surface system (GLASS). GLASS electrodes are readily and uniformly fabricated by simple spin‐coating and cross‐linking of polyallylamine on virtually any kinds of electrodes within 5 min under ambient conditions. Intrinsically hydrophilic gel overlayers with interconnected open pores allow the physical separation of bubble adhesion and catalytic active sites, reducing bubble adhesion strength, and promoting the removal of gas bubbles. As a result, GLASS electrodes exhibit greatly enhanced efficiency and stability for diverse gas evolution reactions, such as hydrogen evolution, hydrazine oxidation, and oxygen evolution reactions. This study provides deeper insights into understanding the effect of the hydrophilic microenvironment on gas evolution reactions and designing practical electrochemical devices.

Interface engineering of bifunctional nickel hydroxide/ nickel phosphide heterostructure for efficient intermittent hydrazine-assisted water splitting

Hydrazine oxidation reaction (HzOR) has been proposed to replace the sluggish oxygen evolution reaction (OER) for energy-saving hydrogen generation. However, the rational design of bifunctional electrocatalysts that can simultaneously accelerate HER/HzOR kinetics and the source of the hydrazine chemical substrate are still challenging. Herein, interfacial heterogeneous nickel hydroxide/nickel phosphide microstructures are in-situ grown on nickel foam (Ni(OH)2/Ni2P/NF) via a combined electrodeposition-phosphorization-electrodeposition strategy. After Ni(OH)2 modification, a charge redistribution is triggered between Ni(OH)2 and Ni2P, reducing the charge-transfer resistance and optimizing the adsorption energy of reaction intermediates. Ni(OH)2/Ni2P/NF thus yields an impressive bifunctional electrocatalytic activity for HER and HzOR with potentials of −72 and −14 mV at 10 mA cm−2, respectively. When using Ni(OH)2/Ni2P/NF as both electrodes, decreased cell voltage of 0.357 V is required to drive a current density of 100 mA cm−2 in 0.5 M hydrazine-containing alkaline electrolyte. Furthermore, an intermittent hydrazine-assisted water electrolysis system is proposed to make the combination of hydrazine sewage purification and energy-saving hydrogen production realistic.

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.

Highly enhanced hydrazine oxidation on bifunctional Ni tailored by alloying for energy-efficient hydrogen production

The low-potential hydrazine oxidation reaction (HzOR) can replace the oxygen evolution reaction (OER) and thus assemble with the hydrogen evolution reaction (HER), consequently achieving energy-saving hydrogen (H2) production. Notably, developing sophisticated bifunctional electrocatalysts for HER and HzOR is a prerequisite for efficient H2 production. Alloying noble metals with eligible non-precious ones can increase affordability, catalytic activity, and stability, alongside rendering bifunctionality. Herein, RuNi alloy deposited onto carbon (RuNi/C) was directly prepared by a simple and highly practical co-reduction method, showing excellent performance for HER and HzOR. Interestingly, to achieve 10 mA cm−2, RuNi/C only required an ultralow potential of 24 mV for HER, on par with commercial 20 wt% platinum in carbon (Pt/C), and −65 mV for HzOR, surpassing most reported counterparts. Moreover, the two-electrode electrolyzer only required small operation voltages of 57.8 and 327 mV to drive 10 and 100 mA cm−2, respectively. Driven by a homemade hydrazine (N2H4) fuel cell and solar panel, appreciable H2 yields of 1.027 and 1.406 mmol h−1 were achieved, respectively, exhibiting the energy-saving advantages alongside robust practicability. Moreover, theoretical calculations revealed that alloying with Ru endows bifunctional Ni sites not only with a lower H2O dissociation barrier but also with more favorable H* adsorption alongside the reduced energy barrier between HzOR intermediates.

Energy-Efficient and Self-Powered Green Ammonia Synthesis by Electrochemical Nitrate Reduction Combined with Hydrazine Oxidation.

To achieve the global goal of carbon neutrality, recently, emphasis has been placed on developing green ammonia production method to replace the Haber-Bosch process. Nitrate reduction reaction (NO3 RR) has received considerable attention, especially for electrochemically producing ammonia from nitrate and simultaneously purifying wastewater. This study first demonstrates that the combination of NO3 RR with hydrazine oxidation reaction (HzOR) is an energy efficient green ammonia production method, which overcomes the sluggish water oxidation limitation. Tungsten phosphide (WP) nanowires (NWs) are prepared as cathode NO3 RR electrocatalysts, which exhibit a high Faradaic efficiency in both neutral (≈93%) and alkaline (≈85%) media. Furthermore, they show a high bifunctional activity in anodic reactions and exhibit a low potential 0.024V for generating a current density of 10mAcm-2 in HzOR. The overall NO3 RR-HzOR required an impressively low potential of 0.24V for generating a current density of 10mAcm-2 ; this potential is much lower than those required for NO3 RR-OER (1.53V) and NO3 RR-UOR (1.31V). A self-powered ammonia production system, prepared by assembling an NO3 RR-HzOR with a perovskite solar cell, displays a high ammonia production rate of 1.44mgcm-2 h-1 . A single PV cell provides enough driving voltage in the PV-EC due to low required potential. This system facilitates unassisted green ammonia synthesis with a low energy consumption and also allows upcycling of wastewater to produce useful fuel.

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.

Cooperative Ni(Co)‐Ru‐P Sites Activate Dehydrogenation for Hydrazine Oxidation Assisting Self‐powered H2 Production

AbstractWater electrolysis for H2 production is restricted by the sluggish oxygen evolution reaction (OER). Using the thermodynamically more favorable hydrazine oxidation reaction (HzOR) to replace OER has attracted ever‐growing attention. Herein, we report a twisted NiCoP nanowire array immobilized with Ru single atoms (Ru1−NiCoP) as superior bifunctional electrocatalyst toward both HzOR and hydrogen evolution reaction (HER), realizing an ultralow working potential of −60 mV and overpotential of 32 mV for a current density of 10 mA cm−2, respectively. Inspiringly, two‐electrode electrolyzer based on overall hydrazine splitting (OHzS) demonstrates outstanding activity with a record‐high current density of 522 mA cm−2 at cell voltage of 0.3 V. DFT calculations elucidate the cooperative Ni(Co)−Ru−P sites in Ru1−NiCoP optimize H* adsorption, and enhance adsorption of *N2H2 to significantly lower the energy barrier for hydrazine dehydrogenation. Moreover, a self‐powered H2 production system utilizing OHzS device driven by direct hydrazine fuel cell (DHzFC) achieve a satisfactory rate of 24.0 mol h−1 m−2.

Cooperative Ni(Co)-Ru-P Sites Activate Dehydrogenation for Hydrazine Oxidation Assisting Self-powered H2 Production.

Water electrolysis for H2 production is restricted by the sluggish oxygen evolution reaction (OER). Using the thermodynamically more favorable hydrazine oxidation reaction (HzOR) to replace OER has attracted ever-growing attention. Herein, we report a twisted NiCoP nanowire array immobilized with Ru single atoms (Ru1 -NiCoP) as superior bifunctional electrocatalyst toward both HzOR and hydrogen evolution reaction (HER), realizing an ultralow working potential of -60 mV and overpotential of 32 mV for a current density of 10 mA cm-2 , respectively. Inspiringly, two-electrode electrolyzer based on overall hydrazine splitting (OHzS) demonstrates outstanding activity with a record-high current density of 522 mA cm-2 at cell voltage of 0.3 V. DFT calculations elucidate the cooperative Ni(Co)-Ru-P sites in Ru1 -NiCoP optimize H* adsorption, and enhance adsorption of *N2 H2 to significantly lower the energy barrier for hydrazine dehydrogenation. Moreover, a self-powered H2 production system utilizing OHzS device driven by direct hydrazine fuel cell (DHzFC) achieve a satisfactory rate of 24.0 mol h-1 m-2 .

Modulation of Electron Structure and Dehydrogenation Kinetics of Nickel Phosphide for Hydrazine‐Assisted Self‐Powered Hydrogen Production in Seawater

AbstractThe electrocatalytic production of hydrogen from seawater provides a low‐cost way to realize energy conversion, but is restricted by high potential for seawater electrolysis and the chlorine oxidation reaction (ClOR) at the anode. Here, the self‐growth of Mo‐doped Ni2P nanosheet arrays with rich P vacancies on molybdenum‐nickel foam (MNF) (Mo‐Ni2Pv@MNF) is reported as bifunctional catalyst for Cl‐free hydrogen production by coupling hydrogen evolution reaction (HER) with hydrazine oxidation reaction (HzOR) in seawater. Impressively, the Mo‐Ni2Pv@MNF electrode as bifunctional catalyst has an excellent activity for overall hydrazine splitting (OHzS) with an ultralow voltage of only 571 mV at 1000 mA cm−2 and can maintain stability for an ultra‐long time of 1000 h at 100 mA cm−2. Moreover, integration of OHzS into self‐assembled hydrazine fuel cells (DHzFC) or solar cells can enable the self‐powered H2 production. The industrial hydrazine sewage as feed for the above eletrolysis system can be degraded to ≈5 ppb rapidly. Density functional thoery calculations demonstrate that the electronic structure modulation induced by P vacancies and Mo doping can not only achieve thermoneutral ΔGH* for hydrogen evolution reaction but also enhance dehydrogenation kinetics from *N2H4 to *NHNH2 for HzOR, achieving enhanced dehydrogenation kinetics.

Boron-doped iridium nanosheets array for energy-saving hydrogen production by hydrazine-assisted water electrolysis

The hydrazine oxidation-assisted water electrolysis process offers an energy-efficient way to produce hydrogen, and it relies on the design of bifunctional catalysts to achieve maximum efficiency. Here, boron-doped iridium (Ir) nanosheets supported on nickel foam (NF) (IrB NSs/NF) was successfully synthesized by a two-step method. As a result of its unique morphology and the lattice strain that the boron atoms cause, IrB NSs/NF exhibit excellent electrocatalytic properties in both hydrogen evolution reactions (HER) and hydrazine oxidation reactions (HzOR). For HER, an ultralow working potential of 18 mV is needed, while for HzOR, a potential of −0.015 V is needed. This work brings new insight into the design of bifunctional catalysts toward efficient hydrogen production and beyond.

The development of a gas-feeding CO2 fuel cell using direct hydrazine oxidation reaction

Electrochemical carbon dioxide (CO2) reduction has attracted attention for converting CO2 into value-added products at room temperature. Conventional electrochemical CO2 reduction methods require external energy because of the high overpotential of the oxygen evolution reaction (OER). To overcome the limitation of the OER, we propose a gaseous CO2 reduction system that uses an aqueous hydrazine (N2H4) oxidation reaction. In this study, the N2H4-CO2 fuel cell is proposed for the simultaneous generation of electricity with CO2 conversion. During the operation of the aqueous N2H4/gas-feeding CO2 fuel cell, a power density of 20.31 mW/cm2 was obtained and 49.20 % of CO2 was converted to CO at the Ag cathode. We also evaluated the correlation between the flow rate of the anolyte and the hydrophobicity of the Ag cathode in terms of cell performance.

Co3O4 Nanocube-Templated CoS2 and CoS2/MoS2 Heterostructures for Multifunctional Electrocatalysis

The design and development of efficient and low-cost electrocatalysts for both anodic (oxygen evolution reaction (OER)/hydrazine oxidation reaction (HzOR)) and cathodic (hydrogen evolution reaction (HER)) reactions are the major challenges for cleaner hydrogen production. Especially, the fabrication of electrocatalysts with abundant electrochemically active sites through simple synthetic routes is of great interest to draw excellent catalytic efficiency. This report provides a strategy to prepare CoS2–MoS2 heterostructures and spheroid-like CoS2 through the sulfurization reaction from the common Co3O4 nanocube precursor in the presence and absence of the molybdenum precursor, respectively. The as-prepared CoS2–MoS2 (25) heterostructure (prepared with 25 mg of Co3O4) shows excellent HER activity in 1 M KOH by delivering a current density of 10 mA/cmgeo2 at an overpotential of 92.5 ± 3.1 mV. The observed enhancement in the HER activity is attributed to the improved water dissociation kinetics at the abundant interfacial area shared between the two components of the heterostructure. Besides, spheroid-like CoS2 shows good OER and hydrazine oxidation reaction (HzOR) activity owing to the high electrochemically active surface area. In addition, the alkaline electrolyzer (HER//OER) constructed using the CoS2–MoS2 (25) heterostructure and spheroid-like CoS2 as the cathode and anode, respectively, delivers a current density of 10 mA/cmgeo2 at a cell potential of 1.67 V. Furthermore, the hydrazine-assisted electrolyzer (HER//HzOR) displays a low cell potential of 0.53 V to attain the same current density along with excellent durability up to 30 h.

Phosphorus-Modified Amorphous High-Entropy CoFeNiCrMn Compound as High-Performance Electrocatalyst for Hydrazine-Assisted Water Electrolysis.

Exploiting highly active and bifunctional catalysts for both hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR) is a prerequisite for the hydrogen acquisition. High-entropy materials have received widespread attention in catalysis, but the high-performance bifunctional electrodes are still lacking. Herein, a novel P-modified amorphous high-entropy CoFeNiCrMn compound is developed on nickel foam (NF) by one-step electrodeposition strategy. The achieved CoFeNiCrMnP/NF delivers remarkable HER and HzOR performance, where the overpotentials as low as 51 and 268mV are realized at 100mAcm-2 . The improved cell voltage of 91mV is further demonstrated at 100mAcm-2 by assessing CoFeNiCrMnP/NF in the constructed hydrazine-assisted water electrolyser, which is almost 1.54V lower than the HER||OER system. Experimental results confirm the important role of each element in regulating the bifuncational performance of high-entropy catalysts. The main influencing elements seem to be Fe and Ni for HER, while the P-modification and Cr metal may contribute a lot for HzOR. These synergistic advantages help to lower the energy barriers and improve the reaction kinetics, resulting in the excellent bifunctional activity of the CoFeNiCrMnP/NF. The work offers a feasible strategy to develop self-supporting electrode with high-entropy materials for overall water splitting.

Printing specific active sites for ORR and hydrazine oxidation on N-doped carbon

Among the prime challenges in clean energy research, the development of simple, cost-effective, and feasible strategies to prepare catalysts can be highlighted. As an alternative, herein N-doped carbonaceous catalysts were synthesized by the same cost-effective method, which can be used to produce both the anode and cathode of the fuel cell. The catalysts were obtained by pyrolysis of melamine-formaldehyde resins containing ions Cu2+, Co2+, or Ni2+ and used for oxygen reduction reaction (ORR) and hydrazine oxidation reaction (HzOR). Although the results prove that the activities for both reactions are derived exclusively from N-doped carbon moieties, the presence of some metal in the pyrolysis process is primordial to printing active sites on carbon structures. The catalyst obtained from Cu-based resin was superior regarding ORR, whilst that yielded from Co-based resin showed the best results for HzOR, indicating that the active sites generated for electroreduction and electrooxidation in each carbon structure are different. The best catalysts demonstrate ORR and HzOR activities very akin to the golden standard 20% Pt/C, presenting a ηonset values of 90 mV and 170 mV.

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

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

Heteroatom-Induced Accelerated Kinetics on Nickel Selenide for Highly Efficient Hydrazine-Assisted Water Splitting and Zn-Hydrazine Battery

HighlightsUltrathin P and Fe co-doped NiSe2 nanosheets supported on modified Ni foam are synthesized, which shows desirable bifunctional electrocatalytic hydrogen evolution reaction (HER)/hydrazine oxidation reaction (HzOR) performance in hydrazine-assisted water electrolysis and Zn-Hz battery.The coexistence of P and Fe heteroatoms induces an accelerated “2 + 2” reaction mechanism with a two-step HER process and a two-step HzOR step.