Nickel three-dimensional (3D) urchin-like particles and one-dimensional (1D) chainlike nanowires are selectively synthesized by an in situ magnetic-field-directed solution-phase method at ambient ...conditions. The results indicate that the morphology of the products strongly depends on the external magnetic-field distribution. The urchin-like particle is composed of a spheric core connected by spear-shaped branches under the nonuniform magnetic field, while the chainlike nanowire is formed through 1D alignment of spheres with the aid of parallel magnetic-field distribution during the reaction. The branch lengths and the whole size of the urchin-like particles can be tailored by adjusting the pH value and reaction temperature, respectively. The magnetic properties of the urchin-like particles are studied in detail as well and the results reveal that the saturated magnetization and coercivity are strongly related to the corresponding microstructure. This work provides a simple and effective strategy to modulate the morphology of the magnetic materials through the external magnetic-field force.
Hydrazine oxidation assisted water electrolysis offers a unique rationale for energy‐saving hydrogen production, yet the lack of effective non‐noble‐metal bifunctional catalysts is still a grand ...challenge at the current stage. Here, the Mo doped Ni3N and Ni heterostructure porous nanosheets grow on Ni foam (denoted as MoNi3N/Ni/NF) are successfully constructed, featuring simultaneous interface engineering and chemical substitution, which endow the outstanding bifunctional electrocatalytic performances toward both hydrazine oxidation reaction (HzOR) and hydrogen evolution reaction (HER), demanding a working potential of −0.3 mV to reach 10 mA cm−2 for HzOR and −45 mV for that of HER. Impressively, the overall hydrazine splitting (OHzS) system requires an ultralow cell voltage of 55 mV to deliver 10 mA cm−2 with remarkable long‐term durability. Moreover, as a proof‐of‐concept, economical H2 production systems utilizing OHzS unit powered by a waste AAA battery, a commercial solar cell, and a homemade direct hydrazine fuel cell (DHzFC) are investigated to inspire future practical applications. The density functional theory calculations demonstrate that the synergy of Mo substitution and abundant Ni3N/Ni interface owns a more thermoneutral value for H* absorption ability toward HER and optimized dehydrogenation process for HzOR.
The Mo doped Ni3N and Ni heterostructure porous nanosheets grow on Ni foam (denoted as Mo–Ni3N/Ni/NF) are able to realize the bifunctionality toward the hydrazine oxidation assisted energy‐saving hydrogen production, which can be attributed to the synergistic effect of interface engineering and chemical substitution.
Transition-metal diselenides have been extensively studied as desirable anode candidates for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) because of their high theoretical ...capacities. However, it is of great challenge to achieve satisfactory cycling performance, especially for larger sodium ion storage, originated from electrode deterioration upon large volume change. Herein, we reported the construction of hierarchical tubular hybrid nanostructures through encapsulating CoSe2 nanoparticles into MoSe2/C composite shells via a simple two-step strategy including a hydrothermal method followed by vapor-phase selenization process. The unique tubular structure enables the highly reversible Li/Na storage with high specific capacity, enhanced cycling stability, and superior rate performance. It is indicated that the contribution of partial pseudocapacitive behavior greatly improves the rate capability for SIBs, where a high capacity retention of 81.5% can be obtained when the current densities range from 0.1 to 3 A g–1 (460 mA h g–1 at 0.1 A g–1 vs 379 mA h g–1 at 3 A g–1). This work provides an effective design rationale on transition-metal diselenide-based tubular nanostructures as superior hosts for both Li and Na ions, which could push forward the development of practical applications of transition-metal diselenide-based anodes in LIBs and SIBs.
P2‐type Na0.67Ni0.33Mn0.67O2 is a dominant cathode material for sodium‐ion batteries due to its high theoretical capacity and energy density. However, charging P2‐type Na0.67Ni0.33Mn0.67O2 to ...voltages higher than 4.2 V (vs. Na+/Na) can induce detrimental structural transformation and severe capacity fading. Herein, stable cycling and moisture resistancy of Na0.67Ni0.33Mn0.67O2 at 4.35 V (vs. Na+/Na) are achieved through dual‐site doping with Cu ion at transition metal site (2a) and unusual Zn ion at Na site (2d) for the first time. The Cu ion doping in 2a site stabilizes the metal layer, while more importantly, the unusual alkali‐metal site doping by Zn ion serves as O2‐Zn2+O2‐ “pillar” for enhancing electrostatic cohesion between two adjacent transition metal layers, preventing the crack of active material along the a–b‐plane and restraining the generation of O2 phase upon deep desodiation. This unique dual‐site‐doped Na0.67Zn0.05Ni0.18Cu0.1Mn0.67O2 cathode exhibits a prominent cyclability with 80.6% capacity retention over 2000 cycles at an ultrahigh rate of 10C, demonstrating its great potential for practical applications. Impressively, the full cell devices with Na0.67Zn0.05Ni0.18Cu0.1Mn0.67O2 and commercial hard carbon as cathode and anode, respectively, can deliver a high energy density of 217.9 Wh kg‐1 and excellent cycle life over 1000 cycles.
Unusual site‐selective doping with Cu ion at transition metal site (2a) and unusual Zn ion at Na site (2d) for P2‐ Na0.67Ni0.33Mn0.67O2 can effectively restrain P2–O2 phase transition and prevent material crack due to the enhanced electrostatic cohesions between two transition metal layers, leading to ultralong life span sodium‐ion full cell.
Water electrolysis has been expected to assimilate the renewable yet intermediate energy‐derived electricity for green H2 production. However, current benchmark anodic catalysts of Ir/Ru‐based ...compounds suffer severely from poor dissolution resistance. Herein, an effective modification strategy is proposed by arming a sub‐nanometer RuO2 skin with abundant oxygen vacancies to the interconnected Ru clusters/carbon hybrid microsheet (denoted as Ru@V‐RuO2/C HMS), which can not only inherit the high hydrogen evolution reaction (HER) activity of the Ru, but more importantly, activate the superior activity toward the oxygen evolution reaction (OER) in both acid and alkaline conditions. Outstandingly, it can achieve an ultralow overpotential of 176/201 mV for OER and 46/6 mV for the HER to reach 10 mA cm−2 in acidic and alkaline solution, respectively. Inspiringly, the overall water splitting can be driven with an ultrasmall cell voltage of 1.467/1.437 V for 10 mA cm−2 in 0.5 m H2SO4/1.0 m KOH, respectively. Density functional theory calculations reveal that armoring the oxygen‐vacancy‐enriched RuO2 exoskeleton can cooperatively alter the interfacial electronic structure and make the adsorption behavior of hydrogen and oxygen intermediates much close to the ideal level, thus simultaneously speeding up the hydrogen evolution kinetics and decreasing the energy barrier of oxygen release.
The Ru@V‐RuO2/C HMS core–shell heterostructure is explored by thermally controlled oxidation of the Ru/C hybrid microsheet to arm the oxygen‐vacancy‐enriched RuO2 sub‐nanometer skin on Ru core, – displaying ultrasmall overpotentials of 176/201 mV for the oxygen evolution reaction and 46/6 mV toward the hydrogen evolution reaction at 10 mA cm−2 in 0.5 m H2SO4/1.0 m KOH, respectively.
Clean hydrogen evolution through electrochemical water splitting underpins various innovative approaches to the pursuit of sustainable energy conversion technologies, but it is blocked by the ...sluggish anodic oxygen evolution reaction (OER). The hydrazine oxidation reaction (HzOR) has been considered as one of the most promising substitute for OER to improve the efficiency of hydrogen evolution reaction (HER). Herein, we construct novel dual nanoislands on Ni/C hybrid nanosheet array: one kind of island represents the part of bare Ni particle surface, while the other stands for the part of core–shell Ni@C structure (denoted as Ni‐C HNSA), in which exposed Ni atoms and Ni‐decorated carbon shell perform as active sites for HzOR and HER respectively. As a result, when the current density reaches 10 mA cm−2, the working potentials are merely −37 mV for HER and ‐20 mV for HzOR. A two‐electrode electrolyzer exhibits superb activity that only requires an ultrasmall cell voltage of 0.14 V to achieve 50 mA cm−2.
A Ni/C hybrid nanosheet array with dual‐active nanoisland sites is reported. One type of island represents the bare Ni particle surface, the other consists of core–shell Ni@C structures (denoted as Ni‐C HNSA). The catalyst achieves efficient hydrogen production in an overall hydrazine splitting, showing its potential for practical applications.
Lithium metal is an ideal electrode material for future rechargeable lithium metal batteries. However, the widespread deployment of metallic lithium anode is significantly hindered by its dendritic ...growth and low Coulombic efficiency, especially in ester solvents. Herein, by rationally manipulating the electrolyte solvation structure with a high donor number solvent, enhancement of the solubility of lithium nitrate in an ester‐based electrolyte is successfully demonstrated, which enables high‐voltage lithium metal batteries. Remarkably, the electrolyte with a high concentration of LiNO3 additive presents an excellent Coulombic efficiency up to 98.8 % during stable galvanostatic lithium plating/stripping cycles. A full‐cell lithium metal battery with a lithium nickel manganese cobalt oxide cathode exhibits a stable cycling performance showing limited capacity decay. This approach provides an effective electrolyte manipulation strategy to develop high‐voltage lithium metal batteries.
The dissolution of LiNO3 in ester‐based electrolyte is realized by the use of γ‐butyrolactone (GBL) as the co‐solvent. NO3− exists in the electrolyte in the form of a contact‐ion pair (CIP), which manipulates the solid–electrolyte interphase layer on the lithium metal anode and promotes the stability of the lithium metal anode.
Clean hydrogen evolution through electrochemical water splitting underpins various innovative approaches to the pursuit of sustainable energy conversion technologies, but it is blocked by the ...sluggish anodic oxygen evolution reaction (OER). The hydrazine oxidation reaction (HzOR) has been considered as one of the most promising substitute for OER to improve the efficiency of hydrogen evolution reaction (HER). Herein, we construct novel dual nanoislands on Ni/C hybrid nanosheet array: one kind of island represents the part of bare Ni particle surface, while the other stands for the part of core-shell Ni@C structure (denoted as Ni-C HNSA), in which exposed Ni atoms and Ni-decorated carbon shell perform as active sites for HzOR and HER respectively. As a result, when the current density reaches 10 mA cm
, the working potentials are merely -37 mV for HER and -20 mV for HzOR. A two-electrode electrolyzer exhibits superb activity that only requires an ultrasmall cell voltage of 0.14 V to achieve 50 mA cm
.
P2‐type layered NaxMnO2 cathode shows great potential in practical sodium ion batteries, especially for grid‐level applications due to its eco‐friendly and cost‐effective sodium and manganese ...resources, and high theoretical specific capacity. However, several obstacles including severe phase transitions of P2‐O2 and P2‐P2′, low redox potential of Mn3+/Mn4+, disproportionation reaction and Jahn‐Teller distortion of Mn3+, and deficient behavior have already hindered its practical applications. Herein, a Li, Cu co‐doping strategy to tackle the mentioned obstacles by activating the oxygen redox is presented. The Li, Cu co‐doped material exhibits solid solution reaction without any phase transitions as proved by in situ X‐ray diffraction measurement and reduces the dissolution of active manganese element. With this modification treatment, it can dramatically raise the cycling stability from 30.4% to 80.1% after 150 cycles and simultaneously improves the deficient behavior due to the capacity contribution of oxygen redox at high voltage. More importantly, the coin‐cell type sodium ion full cell assembled with this cathode and commercial hard carbon anode delivers a promising energy density of 225.1 Wh kg–1.
A Li, Cu co‐doped layered P2‐NaxMnO2 is subtly designed via a cost‐effective sol‐gel method. The co‐doped material shows phase‐transition‐free nature at high voltage due to the activation of oxygen redox, and mitigates the Jahn–Teller distortion and dissolution of Mn2+, contributing to the enhanced rate and cyclic capability.
