Chicken nuggets-like core/shell nanosheet arrays as high performance flexible all-solid-state supercapacitor cathode and buckwheat shell as anode

The energy density of a flexible all-solid-state supercapacitor (ASC) requires new electrode material with special structure and morphology as a prerequisite for its secured improvement. In this paper, a new morphological exploration of chicken nuggets-like core/shell NiCo₂O₄/MnO₂ (NCM) nanosheet arrays on Ni foam was employed. The application of this special morphology aims to greatly improve the electrochemical performance of the cathode electrode. Additionally, Buckwheat Biochar (BBC) is utilized as the anode while the PVA/KOH thin film is prepared as the separator. The chicken nuggets-like core/shell NCM nanosheet arrays were obtained by a two-step hydrothermal method. A series of characterization methods were carried out to further support the core/shell's well-designed structure and precise composition. The tests exhibited excellent specific capacitance of 593.3 F g^?1 at 5 mA cm^?2 and outstanding cycling stability with a retention of 90% after 10000 cycles. Furthermore, the assembled NCM//BBC ASC device indicated a high specific capacitance (239 F g^?1 at the current density of 5 mA cm^?2), this is in due part of the unique architecture of NCM nanosheet arrays and interconnected special porous structure of the BBC and the thin film PVA/KOH. Hence, the assembled ASC device exhibited high energy density (an energy density of 58 Wh·kg^?1 at 3263 W kg^?1) and remarkable cycling stability.     

Micro and nano-architectures of Co3O4 on Ni foam for electro-oxidation of methanol

Spinel Co₃O₄ material with different morphologies is directly grown on Ni foam by simple hydrothermal method and subsequent calcination processes. The direct growth of binder free active phase of Co₃O₄ on Ni foam is an effective approach to enhance the electrocatalytic activity of the material. The morphologies of Co₃O₄ strongly depend on the anion of the precursor salt used. Microflowers, microspheres and nanograss morphologies of Co₃O₄ are obtained using chloride, sulfate and acetate salts of cobalt, respectively. The BET surface areas of these cobalt oxide materials are found to increase in the order of microflower-Co₃O₄ (53 m² g^?1) < nanograss-Co₃O₄ (65 m² g^?1) < microsphere-Co₃O₄ (100 m² g^?1). The electrocatalytic activity of these Co₃O₄ materials has been tested for methanol oxidation by cyclic voltammetry and chronoamperometry. All three samples show low onset potentials (0.32–0.34 V) for methanol oxidation. The vanodic peak current of methanol oxidation is found to increase in the order of microflower-Co₃O₄ (28 A g^?1) < nanograss-Co₃O₄ (34.9 A g^?1) < microsphere-Co₃O₄ (36.2 A g^?1) at 0.6 V. This study highlights the significance of the morphology of cobalt oxide in the development of oxide based non-precious electrocatalysts for methanol oxidation.     

CuO nanosheets grown on cupper foil as the catalyst for H2O2 electroreduction in alkaline medium

The growth of CuO nanosheet arrays on Cu foil was demonstrated. The morphology and structure of the CuO were examined by scanning electron microscopy and X-ray diffraction spectroscopy. The catalytic performance of the obtained CuO/Cu electrode for hydrogen peroxide electroreduction in 3.0 mol dm⁻³ KOH was evaluated by means of cyclic voltammetry and chronoamperometry. The CuO/Cu electrode shows an onset potential for H₂O₂ electroreduction comparable to Co₃O₄ nanowire arrays grown on Ni foam and around 100 mV more negative than precious metal catalysts, such as Pt and Pd, demonstrating its good catalytic activity for H₂O₂ electroreduction. The stabilized mass current density for H₂O₂ electroreduction on the CuO/Cu electrode at −0.3 V reached about 57% of that on Co₃O₄ nanowire arrays grown on nickel foam. Compared to conventional fuel cell electrodes fabricated by mixing active materials with conducting agents and polymer binders, this electrode of CuO nanosheet arrays directly grown on Cu has superior mass transport property, which combining with its low-cost and facile preparation, make it a promising electrode for fuel cell using H₂O₂ as the oxidant.     

Co3O4 nanosheet arrays treated by defect engineering for enhanced electrocatalytic water oxidation

Due to its poor electrical conductivity and finite exposed active sites, the development of high activity Co₃O₄ oxygen evolution reaction (OER) electrocatalysts remains a major challenge. Oxygen vacancies can enhance the electrical conductivity of electrocatalysts and reduce the adsorption energy of H₂O molecules on surfaces, thereby significantly enhancing their electrocatalytic activity. Taking inspiration from this, we demonstrate a green and facile reduction strategy to prepare reduced Co₃O₄ nanosheet arrays (R-Co₃O₄ NSA) with large electrochemical surface area and rich in surface oxygen vacancies. Compared to pristine Co₃O₄ nanosheet arrays (P-Co₃O₄ NSA), R-Co₃O₄ NSA exhibits better OER performance, with a lower overpotential of 330 mV at a current density of 20 mA cm^?2 and a smaller Tafel slope of 72 mV dec^?1. Impressively, the excellent properties of R-Co₃O₄ NSA can rival to the state-of-the-art noble metal oxide electrocatalyst (IrO₂). This strategy of defect-engineering offers a briefness and cost-effective means for the development of highly efficient OER systems.     

Simple synthesis of honeysuckle-like CuCo2O4/CuO composites as a battery type electrode material for high-performance hybrid supercapacitors

In this paper, porous CuCo₂O₄/CuO composites with novel honeysuckle-like shape (CuCo₂O₄/CuO HCs) have been prepared for the first time by a simple hydrothermal method and followed with an additional annealing process in air. The unique CuCo₂O₄/CuO HCs consisted of dense and slender petals with length of 1.3–1.5 μm and width of about 50 nm, and possessed a specific surface area of 36.09 m² g^?1 with main pore size distribution at 10.63 nm. When used as the electrode materials for supercapacitors, the CuCo₂O₄/CuO HCs exhibited excellent electrochemical performances with a high specific capacity of 350.69 C g^?1 at 1 A g^?1, a rate capability of 78.6% at 10 A g^?1, and 96.2% capacity retention after 5000 cycles at a current density of 5 A g^?1. In addition, a hybrid supercapacitor (CuCo₂O₄/CuO HCs//AC HSC) was assembled using the CuCo₂O₄/CuO HCs as positive electrode and activated carbon (AC) as negative electrode. The HSC device delivered a specific capacity of 187.85 C g^?1 at 1 A g^?1 and a superior cycling stability with 104.7% capacity retention after 5000 cycles at 5 A g^?1, and possessed a high energy density of 41.76 W h kg^?1 at a power density of 800.27 W kg^?1. These outstanding electrochemical performances manifested the great potential of CuCo₂O₄/CuO HCs as a promising battery-type electrode material for the next-generation advanced supercapacitors with high-performance.     

Boosting the capacitance of NiCo2O4 hierarchical structures on nickel foam in supercapacitors

A facile method of directly growing NiCo₂O₄ hybrid hierarchical nanostructures on nickel foam is developed by a hydrothermal and post heat-treatment method without using any surfactant, stabilizer or organic binder. Due to the rich porous nanostructures, relative large specific surface area (177.71 m² g^?1) of the NiCo₂O₄ hybrid structure and efficient electrical contact with the conductive nickel substrate, the NiCo₂O₄NF hybrid electrode shows significantly enhanced specific capacitance (3105.1 F g^?1 at 1 A g^?1), outstanding rate properties (1621.3 F g^?1 at 20 A g^?1 and 1191.5 F g^?1 at 50 A g^?1) and high energy density (95.26 Wh kg^?1). This facile and effective design method opens up new possibilities for producing binder-free electrodes in high-performance electrochemical supercapacitors and miniaturized devices.     

Single-step hydrothermal synthesis of WO3-MnO2 composite as an active material for all-solid-state flexible asymmetric supercapacitor

In present study, new strategy is employed to build composite nanostructure and asymmetric configuration to enhance the capacitive performance of supercapacitor device. The WO₃-MnO₂ composite with mesoporous structure is prepared by single-step hydrothermal method and used to gain superior electrochemical performance in asymmetric configuration. A binder-free and additive-less WO₃-MnO₂ composite electrode exhibits high specific capacitance of 609 F g^?1 at a scan rate of 5 mV s^?1. The flexible asymmetric supercapacitor device with WO₃-MnO₂ as a positive electrode and WO₃ as a negative electrode demonstrates stable operating potential window of 1.4 V with specific capacitance of 103 F g^?1 at a scan rate of 5 mV s^?1 and energy density of 24.13 Wh kg^?1 at power density of 915 W kg^?1. Furthermore, WO₃-MnO₂//WO₃ device exhibits good cycle life with capacity retention of 95% after 2500 cycles and excellent mechanical flexibility. These results reveal the potential of WO₃-MnO₂ composite electrode for fabrication of high-performance supercapacitors.     

High-performance hybrid supercapacitor based on the porous copper cobaltite/cupric oxide nanosheets as a battery-type positive electrode material

In this work, CuCo₂O₄/CuO nanosheets (NSs) and CuCo₂O₄ oblique prisms (OPs) were synthesized at 130 °C with different amounts of hexamethyltetramine (HMTA) and reaction time through a hydrothermal method, and followed by an annealing treatment of precursors in air. The CuCo₂O₄/CuO NSs with 40 nm in thickness possessed a large specific surface area of 43.34 m² g⁻¹ and a mean pore size of 18.14 nm. The electrochemical tests revealed that the CuCo₂O₄/CuO NSs were belonged to the battery-type electrode material and exhibited a specific capacity of 395.55 C g⁻¹ at the current density of 1 A g⁻¹, higher than 258.16 C g⁻¹ for CuCo₂O₄ OPs. A hybrid supercapacitor (HSC) was assembled with activated carbon (AC) as negative electrode and CuCo₂O₄-based materials as positive electrode. The CuCo₂O₄/CuO NSs//AC HSC exhibited a high energy density of 30.18 Wh kg⁻¹ at a power density of 869.62 W kg⁻¹, and showed a fantastic cycling performance with 105.22% capacity retention over 5000 cycles. In contrast, the CuCo₂O₄ OPs//AC HSC delivered an energy density 26.27 Wh kg⁻¹ at 916.74 W kg⁻¹. These impressive electrochemical properties indicate that CuCo₂O₄/CuO NSs may serve as a promising electrode material for the highly capable hybrid supercapacitors in the near future.     

Synthesis of hierarchical tube-like yolk-shell Co3O4@NiMoO4 for enhanced supercapacitor performance

Transition metal oxides with three-dimensional architectures have attracted great interest as high-performance supercapacitor electrodes. In this work, tube-like yolk-shell Co₃O₄@NiMoO₄ composite were prepared via a two-step synthesis for the first time. Ultrathin NiMoO₄ nanosheets arrayed randomly to form porous shell, which fully covered around Co₃O₄ fibers with interspaces between core and shell. Benefitting from unique structure and chemical composition, the Co₃O₄@NiMoO₄ composite as supercapacitor electrodes exhibited enhanced specific capacitance of 913.25 F g^?1 at high current density of 10 A g^?1 and large capacitance retention of 88% with current density increased from 0.5 to 20 A g^?1 as well as remarkable cycling stability. In addition, NiCo₂O₄@NiMoO₄ and NiFe₂O₄@NiMoO₄ composites with similar morphologies were obtained. Namely, this work exhibits a general approach to reasonable construct and preparation hierarchical structure for high performance supercapacitor electrodes.     

One step synthesis of rGO-Ni3S2 nano-cubes composite for high-performance supercapacitor electrodes

In the last decade, supercapacitors possessing high power density and cyclic stability have attracted great interests in various applications. Graphene-based composite electrodes are known as a promising candidate for supercapacitors due to synergistic effects. For the first time, in this work, we develop a simple one-step hydrothermal synthesis of graphene wrapped Ni₃S₂ nanocubes (rGO-Ni₃S₂) composite for high-performance and low-cost supercapacitor electrodes. The rGO-Ni₃S₂ electrode exhibits an ultrahigh specific capacity of 616 C g^?1 at the current density of 1 A g^?1 with excellent cycling durability of 92.7% after 5000 cycles, which is much better when compared with the counterpart without graphene (pure Ni₃S₂). We attribute the remarkable performance of the rGO-Ni₃S₂ electrode to the synergistic effects of the graphene as the conductive support and Ni₃S₂ cubics as the pseudocapacitive material. This work constitutes a step forward towards the development of low-cost and high-performance supercapacitors for the next generation of portable electronics.     

Oxygen evolution reaction on Ni-substituted Co3O4 nanowire array electrodes

Nanowire arrays of mixed oxides of Co and Ni freely standing on Ni foam are prepared by a template-free growth method. The effects of Ni content on the morphology, structure and catalyst performance for oxygen evolution reaction are investigated by scanning electron microscopy, X-ray diffraction spectroscopy and electrochemical techniques including cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy. A transformation from nanowire arrays to nanoplate arrays is found with the increase of the atomic ratio of Ni to Co in the preparation solution. The Ni_xCo_3−xO₄ electrode obtained at 1:1 of Ni:Co in the preparation solution exhibits nanowire array structure and has better catalytic performance for oxygen evolution reaction than other Ni_xCo_3−xO₄ and Co₃O₄ electrodes. The catalytic activities of the Ni_xCo_3−xO₄ and Co₃O₄ electrodes are correlated with their surface roughness. Superior stability of the Ni_xCo_3−xO₄ nanowire array electrode is demonstrated by a chronopotentiometric test. The reaction orders with respect to OH⁻ on the Ni_xCo_3−xO₄ electrode are close to 2 and 1 at low and high overpotentials, respectively.     

Growth of polyaniline on rGO-Co3S4 nanocomposite for high-performance supercapacitor energy storage

Recently, since the supercapacitors have drawn considerable attention, a vast study have been triggered in order to develop efficient electrodes for responding to the increasing demand of supercapacitors. In this report, a possible approach have been used to prepare a ternary nanocomposite, polyaniline/reduced graphene oxide-cobalt sulfide (PANI/rGO-Co₃S₄). At first, a simple and inexpensive hydrothermal route has been used for the preparation of cobalt sulfide (Co₃S₄) on the surface of graphene oxide sheets (rGO-Co₃S₄). Then, the polyaniline nanorods have been flourished on the surface of rGO-Co₃S₄ sheets via in situ chemical polymerization of aniline which was synergistically adjoined to the graphene surface. Polyaniline has uniformly covered the surface of the rGO-Co₃S₄ due to the rational combination of two components. Combining of PANI with rGO-Co₃S₄ electrode material amplify its electrochemical efficiency in terms of a high specific capacitance of 767 F g^?1 at 1 A g^?1 and 81.7% of specific capacitance maintenance after 5000 cycles due to the creation of synergistic effect. Therefore, the ternary nanocomposite of PANI/rGO-Co₃S₄ provides a new promising pathway for the expanding of high-performance electrode materials for supercapacitors.     

Enhanced performance of supercapacitor based on boric acid doped PVA-H2SO4 gel polymer electrolyte system

Proton Conducting gel polymer electrolytes (GPEs) are taking much attention compared to liquid electrolytes for supercapacitor applications because of their physical properties, electrochemical stability and operation over broader temperature window. Among different GPEs PVA/acid blend electrolytes such as PVA/H₂SO₄, has drawn great attention in recent years. In this study, PVA-H₂SO₄-H₃BO₃ GPE was introduced for electric-double layer capacitor (EDLCs) application, in which electrospun free-standing carbon nanofibers are used as electrodes. Introduced PVA-H₂SO₄-H₃BO₃ GPE serves as both separator and the electrolyte in the supercapacitor. Symmetric Swagelok cells including GPEs were assembled via using two electrode arrangements and the electrochemical properties were searched. Electrochemical performance studies demonstrated that PVA-H₂SO₄-H₃BO₃ GPE had a maximum specific capacitance (Cs) of 134 F g^?1 and showed great capacitance retention (%100) after 1000 charge/discharge cycles. Furthermore, PVA-H₂SO₄-H₃BO₃GPE yielded an energy density of 67 Wh kg^?1 with a corresponding power density of 1000 W kg^?1 at a current density of 1 A g^?1.     

Constructing 3D honeycomb-like CoMn2O4 nanoarchitecture on nitrogen-doped graphene coating Ni foam as flexible battery-type electrodes for advanced supercapattery

Reasonable structural design is significant to enable the performance in advanced energy storage devices. Herein, a 3D honeycomb-like CoMn₂O₄ nanoarchitecture (CMO) on nitrogen-doped graphene (NG) coating Ni foam (denoted as Ni/NG/CMO) flexible battery-type electrode was prepared by a facile two-step hydrothermal strategy. The honeycomb-like CoMn₂O₄ arrays not only provide abundant active sites but can also be closely combined with the Ni foam/NG substrate, which enables high reversible capacity and good cycle stability during the long cycles. Benefiting from the compositional features and 3D honeycomb-like nanoarchitecture, the Ni/NG/CMO composite electrode displays improved electrochemical performance with remarkable specific capacity of 527.0C g⁻¹ at a current density of 1 A g⁻¹, outstanding rate capability (338.6C g⁻¹ even at 20 A g⁻¹). In addition, a flexible binder-free supercapattery device has been assembled with Ni/NG/CMO as positive electrode and 3D Ni/NG as negative electrode. Such a supercapattery delivers a high energy density of 44.1 Wh·kg⁻¹ at 992.6 W kg⁻¹, 20.3 Wh·kg⁻¹ at 12430.0 W kg⁻¹ as well as excellent cycling durability. The 3D honeycomb-like Ni/NG/CMO could be considered as an advanced flexible battery-type material for high capacity and energy density fields.     

CuCo2O4 microflowers catalyst with oxygen evolution activity comparable to that of noble metal

It is of high significance to design efficient, low-cost and durable electrocatalysts for the reaction (OER) in alkaline solution. In this communication, we report the development of CuCo₂O₄ microflowers directly on nickel foam (CuCo₂O₄/NF) as an efficient and durable electrocatalyst for OER. Such CuCo₂O₄/NF demands overpotential of only 296 mV to drive a geometrical catalytic current density of 20 mA cm^?2, 73 mV and 145 mV less than that for Co₃O₄/NF and NF, respectively, which are better than that of RuO₂/NF. Furthermore, CuCo₂O₄/NF presents an excellent long-term electrochemical durability maintaining the activity at overpotential of 240 mV for 10 h.     

One step electrodeposition of V2O5/polypyrrole/graphene oxide ternary nanocomposite for preparation of a high performance supercapacitor

A new ternary nanocomposite based on graphene oxide (GO), polypyrrole (PPy) and vanadium pentoxide (V₂O₅) is obtained via one-step electrochemical deposition process. Electrochemical deposition of V₂O₅, PPy and GO on a stainless steel (SS) substrate is conducted from an aqueous solution containing vanadyl acetate, pyrrole and GO to get V₂O₅/PPy/GO nanocomposite. Characterization of the electrode material is carried out by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). The electrochemical performance of the as-prepared nanocomposite is evaluated by different electrochemical methods including cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) in 0.5 M Na₂SO₄ solution. Remarkably, V₂O₅/PPy/GO nanocomposite shows a specific capacitance of 750 F g^?1 at a current density of 5 A g^?1, which is far better than PPy (59.5 F g^?1), V₂O₅/PPy (81.5 F g^?1) and PPy/GO (344.5 F g^?1). Furthermore, V₂O₅/PPy/GO maintains 83% of its initial value after 3000 cycles, which demonstrates good electrochemical stability of the electrode during repeated cycling. These results demonstrate that the combination of electrical double layer capacitance of GO and pseudocapacitive behavior of the PPy and V₂O₅ can effectively increase the specific capacitance and cycling stability of the prepared electrode. Also, a symmetric supercapacitor device assembled by V₂O₅/PPy/GO nanocomposite yielded a maximum energy density of 27.6 W h kg^?1 at a power density of 3600 W kg^?1, and a maximum power density of 13680 W kg^?1 at an energy density of 22.8 W h kg^?1.     

Crossed FeCo2S4 nanosheet arrays grown on 3D nickel foam as high-efficient electrocatalyst for overall water splitting

Great efforts in developing low-cost, highly efficient and stable electrocatalysts are to tune the chemical compositions and morphological characteristics for enhancing efficiency of water splitting. In this communication, FeCo₂S₄ nanosheet was grown in situ on nickel foam (FeCo₂S₄/NF) via a facile hydrothermal sulfidization method and served as a high-efficient bifunctional electrocatalyst for overall water splitting. As-synthesized FeCo₂S₄/NF self-supported electrode delivers 20 mA cm^?2 at an overpotential of 259 mV toward OER and 10 mA cm^?2 at an overpotential of 131 mV toward HER in alkaline media. Moreover, when used as both anode and cathode in a two-electrode electrolyzer, only a small cell voltage of 1.541 V is needed to afford a current density of 10 mA cm^?2 for overall water splitting. Bifunctional electrode FeCo₂S₄/NF also revealed a distinguished electrochemical durability during a 12 h stability test at 1.63 V, which would provide a promising water splitting installation for commercial hydrogen production.     

Multifunctional catalysts with high catalytic activities: Flower-like Co9S8 microballs assembled with weak crystalline pea pod-shaped nanowires

The flower-like Co₉S₈ microballs assembled with weak crystalline pea pod-shaped nanowires were fabricated via a one-pot hydrothermal reaction. The high-resolution TEM image of pea pod-shaped nanowires revealed a weak crystalline structure. Some regions were amorphous and some regions showed well-resolved lattice fringe. Because flower-like Co₉S₈ microballs possessed the more catalytic active sites of the weak crystalline character and the fast electron transfer along the nanowires, they would be promising catalysts for reduction of I₃^? in DSSCs and electrochemical water splitting. As the counter electrode catalysts for I₃^? reduction, DSSCs based on the Co₉S₈ microballs got a high photoelectrical conversion efficiency of 7.0%, which was comparable with DSSCs based on standard platinum (7.48%). As the electrocatalysts for hydrogen evolution reaction, the Co₉S₈ microball electrode possessed an overpotential of 173.8 and 191.3 mV at the current density of 10 mA cm^?2 in acid and alkaline solution, respectively. Also, it displayed a superior catalytic activity for oxygen evolution reaction. The stability tests indicated that this microball could possess the high catalytic activity with long time. This kind of Co₉S₈ microballs assembled with weak crystalline pea pod-shaped nanowires paved a new way to low-cost catalyst for I₃^? reduction and water splitting.     

Phosphorus-doped nickel sulfides/nickel foam as electrode materials for electrocatalytic water splitting

Hydrogen production from electrocatalytic water splitting is viewed as one of the most promising methods to generate the clean energy. In this work, we successfully prepared an electrode material by growing phosphorus-doped Ni₃S₂ (PNi₃S₂) on nickel foam substrate (NF) under hydrothermal conditions. The phosphorus-doping has an obvious effect on the morphology of Ni₃S₂ on the surface of the nickel foam, which probably results in more active sites, higher electrical conductivity and faster mass transfer. The resulting electrode material displays excellent electrocatalytic activities and stability towards both OER (oxygen evolution reaction) and HER (hydrogen evolution reaction). A relatively low overpotential of 306 mV is required to reach the current density of 100 mA cm^?2 for OER and 137 mV at 10 mA cm^?2 for HER in 1 M KOH solution. When PNi₃S₂/NF was used in an electrolyzer for full water splitting, it can generate a current density of 10 mA cm^?2 at 1.47 V with excellent stability for more than 20 h.     

Porous Ni2P nanoflower supported on nickel foam as an efficient three-dimensional electrode for urea electro-oxidation in alkaline medium

Porous Ni₂P nanoflower supported on nickel foam (Ni₂P@Ni foam) electrodes are synthesized via a simple hydrothermal growth strategy accompanied with further phosphating treatment. The prepared electrodes are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). Electro-catalytic performances towards urea electro-oxidation are tested by cyclic voltammetry (CV), chronoamperometry (CA) coupled with electrochemical impedance spectroscopy (EIS). By phosphating Ni(OH)₂ precursor, the final obtained Ni₂P@Ni foam electrode presents a porous Ni₂P nanoflower structure within abundant porosity, and so exposes a large amount of electro-catalytic active sites and electronic transmission channels to accelerate the interfacial reaction. Compared with Ni(OH)₂@Ni foam precursor, the Ni₂P@Ni foam catalyst exhibits more excellent electro-catalytic activity as well as lower onset oxidation potential. Remarkably, the Ni₂P@Ni foam catalyst reaches a peak current density of 750 mA cm^?2 with an onset oxidation potential of 0.24 V (vs. Ag/AgCl) accompanied by an excellent stability in 0.60 M urea with 5.00 M KOH solutions. Benefiting from the unique porous nanosheet structure, the as-synthesized Ni₂P@Ni foam catalyst performs a highly enhanced catalytic behavior for alkaline urea electro-oxidation, indicating that the material can be hopefully applied in direct urea fuel cells.