In situ growth of ZIF-8-derived ternary ZnO/ZnCo2O4/NiO for high performance asymmetric supercapacitors.
TL;DR: Electrochemical investigation reveals that when the molar ratio of nickel nitrate to cobalt nitrate is 1, the composite material is more outstanding, which shows a high specific capacitance and excellent cycling stability, confirmed by assembling an asymmetric supercapacitor.
Abstract: In this paper, the rational design and synthesis of ZIF-8-derived ternary ZnO/ZnCo2O4/NiO wrapped by nanosheets is introduced. Polyhedral ternary ZnO/ZnCo2O4/NiO composites surrounded by nanosheets with different compositions are successfully fabricated through in situ growth on ZIF-8 templates and subsequent thermal annealing in air. Electrochemical investigation reveals that when the molar ratio of nickel nitrate to cobalt nitrate is 1, the composite material is more outstanding, which shows a high specific capacitance of 1136.4 F g-1 at 1 A g-1 and excellent cycling stability of 86.54% after 5000 cycles. Moreover, the excellent performance of this material is also confirmed by assembling an asymmetric supercapacitor. The assembled hybrid device can reach a large potential range of 0-1.6 V and deliver a high energy density of 46.04 W h kg-1 as well as the maximum power density of 7987.5 W kg-1.
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TL;DR: A facile and effective metal-organic framework (MOF)-derived strategy is introduced to encapsulate multi-shelled zinc-cobalt-selenide hollow nanosphere positive and yolk-double shell cobalt-iron-selsenideollow nanosphere negative electrode materials with controlled shell numbers in a graphene network for supercapacitor applications.
Abstract: The practical exploration of electrode materials with complex hollow structures is of considerable significance in energy storage applications. Mixed-metal selenides (MMSs) with favorable architectures emerge as new electrode materials for supercapacitor (SC) applications owing to their excellent conductivity. Herein, a facile and effective metal–organic framework (MOF)-derived strategy is introduced to encapsulate multi-shelled zinc–cobalt-selenide hollow nanosphere positive and yolk–double shell cobalt–iron-selenide hollow nanosphere negative electrode materials with controlled shell numbers in a graphene network (denoted as G/MSZCS-HS and G/YDSCFS-HS, respectively) for SC applications. Due to the considerable electrical conductivity and unique structures of both electrodes, the G/MSZCS-HS positive and G/YDSCFS-HS negative electrodes exhibit remarkable capacities (∼376.75 mA h g−1 and 293.1 mA h g−1, respectively, at 2 A g−1), superior rate performances (83.4% and 74%, respectively), and an excellent cyclability (96.8% and 92.9%, respectively). Furthermore, an asymmetric device (G/MSZCS-HS//G/YDSCFS-HS) has been fabricated with the ability to deliver an exceptional energy density (126.3 W h kg−1 at 902.15 W kg−1), high robustness of 91.7%, and a reasonable capacity of 140.3 mA h g−1.
108 citations
TL;DR: In this paper, a flexible solid-state hybrid supercapacitor with NiCo2O4Nosheets and activated carbon cloth (AC)/CC is presented, which exhibits a high specific capacitance of 2102 F g−1 at a current density of 1 ǫg−1, good rate capability and outstanding cycling stability.
95 citations
TL;DR: The battery-type NiZn2O4-NiO NFAs electrode material has remarkable application potential and could be effectively applied in other energy storage technologies.
Abstract: The development of combined simple metal oxides and binary metal oxides on a flexible conductor has been needed as a novel approach for energy storage sources. Here, we demonstrate a simple and versatile strategy towards the synthesis of a NiZn2O4-NiO nanoflower array (NFA) composite effectively deposited into a nickel (Ni) foam conductor for energy storing applications to achieve better electrochemical results. The morphology and other physical properties of the as-developed composite were analyzed, and the results suggest that the NiO nanoparticles have been effectively anchored into the binary NiZn2O4 nanoleaves array surface. The composite NiZn2O4-NiO NFAs nanoarchitecture combines superior surface area with huge numbers of active sites to boost electrochemical reactions and excellent transport between electrons and ions, as compared to NiZn2O4 nanoleaf arrays (NLAs). Meanwhile, taking into consideration electrochemical studies, the composite NiZn2O4-NiO NFAs exhibited extraordinary faradaic redox progress, which was different from the metal oxide based electrode profiles. Cyclic voltammetry and galvanostatic charge-discharge plateaus from the NiZn2O4 NLAs and NiZn2O4-NiO NFAs electrodes exhibit faradaic battery-type redox behavior, which is distinct from the profiles of carbon-based materials. As a battery-type electrode, the composite NiZn2O4-NiO NFAs electrode exhibited a greater supercapacitor activity with a higher specific capacitance of 482.7 C g-1 at 1 A g-1 and also yielded the best life-span with up to 98.14% capacity retained after 5000 cycles (vs. 253.4 C g-1 at 1 A g-1 and 91.4% retention of capacity after 5000 cycles for NiZn2O4 NLAs), which was the best result or comparable to recently reported composites of simple metal oxides/binary metal oxides-based electrode materials. Thus, with the above findings, the battery-type NiZn2O4-NiO NFAs electrode material has remarkable application potential and could be effectively applied in other energy storage technologies.
86 citations
15 Nov 2019
TL;DR: A structure-designed synthesis strategy to controllably fabricate hierarchical NiCo2O4@NiO composites on carbon fiber paper to construct high-performance multicomponent electrode materials for supercapacitors is reported here.
Abstract: The design of multicomponent electrode materials is attractive for advanced supercapacitors due to synergistic and multifunctional effects among different active materials. We reported here a structure-designed synthesis strategy to controllably fabricate hierarchical NiCo2O4@NiO composites on carbon fiber paper. The hierarchical structure with NiCo2O4 core and NiO shell provided more active sites for ion transportation and storage to improve utilization rate of electrode materials, enhancing the specific capacitance and rate performance. As an ideal electrode material for supercapacitors, the NiCo2O4@NiO electrode exhibit high specific capacitance (1188 F/g at 2 A/g), excellent rate capability with ∼85% capacitance retained at 10 A/g, and compelling cycling performance (∼106.8% of the initial capacitance retention over 7000 cycles). The present work demonstrated a structure-designed strategy to construct high-performance multicomponent electrode materials for supercapacitors.
83 citations
TL;DR: In this article, an asymmetric supercapacitor is constructed by using CoMoO4-x as positive electrode and activated carbon as negative electrode, which achieves high energy density of 62.3 Wh −h −1 at a power density of 800 W h −1, together with a good cyclic life.
73 citations
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TL;DR: It is demonstrated that methanol can affect the coordination mode of ZIF-67 in the presence of Co(2+) and induces a mild phase transformation under solvothermal conditions and a well-defined hollow Zn/Co ZIF rhombic dodecahedron can be obtained.
Abstract: The rational design of metal–organic frameworks (MOFs) with hollow features and tunable porosity at the nanoscale can enhance their intrinsic properties and stimulates increasing attentions. In this Communication, we demonstrate that methanol can affect the coordination mode of ZIF-67 in the presence of Co2+ and induces a mild phase transformation under solvothermal conditions. By applying this transformation process to the ZIF-67@ZIF-8 core–shell structures, a well-defined hollow Zn/Co ZIF rhombic dodecahedron can be obtained. The manufacturing of hollow MOFs enables us to prepare a noble metal@MOF yolk-shell composite with controlled spatial distribution and morphology. The enhanced gas storage and porous confinement that originate from the hollow interior and coating of ZIF-8 confers this unique catalyst with superior activity and selectivity toward the semi-hydrogenation of acetylene.
652 citations
TL;DR: This is the first synthesis of the LDH non-spherical structures and the Ni-Co LDH nanocages exhibit superior pseudocapacitance property due to their novel hierarchical and submicroscopic structures.
Abstract: Layered double hydroxides (LDHs) are currently attracting intense research interest for their various applications. Three LDH hollow nano-polyhedra are synthesized with zeolitic imidazolate framework-67 (ZIF-67) nanocrystals as the templates. The nanocages well inherit the rhombic dodecahedral shape of the ZIF-67 templates, and the shell is composed of nanosheets assembled with an edge-to-face stacking. This is the first synthesis of the LDH non-spherical structures. And the mechanism of utilizing metal–organic framework (MOF) nanocrystals as templates is explored. Control of the simultaneous reactions, the precipitation of the shells and the template etching, is extremely crucial to the preparation of the perfect nanocages. And the Ni–Co LDH nanocages exhibit superior pseudocapacitance property due to their novel hierarchical and submicroscopic structures.
529 citations
TL;DR: The optimized ZnO@ZIF-8-based nanocomposite sensor shows markedly selective response to H2 in comparison with the pristine ZnNO nanowires sensor, while showing the negligible sensing response to C7H8 and C6H6.
Abstract: Gas sensors are of a great interest for applications including toxic or explosive gases detection in both in-house and industrial environments, air quality monitoring, medical diagnostics, or control of food/cosmetic properties. In the area of semiconductor metal oxides (SMOs)-based sensors, a lot of effort has been devoted to improve the sensing characteristics. In this work, we report on a general methodology for improving the selectivity of SMOx nanowires sensors, based on the coverage of ZnO nanowires with a thin ZIF-8 molecular sieve membrane. The optimized ZnO@ZIF-8-based nanocomposite sensor shows markedly selective response to H2 in comparison with the pristine ZnO nanowires sensor, while showing the negligible sensing response to C7H8 and C6H6. This original MOF-membrane encapsulation strategy applied to nanowires sensor architecture pave the way for other complex 3D architectures and various types of applications requiring either gas or ion selectivity, such as biosensors, photo(catalysts), and ...
316 citations
TL;DR: It was found that both the molecular ratio of Ni to Co and the annealing temperature had significant effects on their porous structure and electrochemical properties, and the effect of the Ni/Co ratio on the pseudocapacitive properties of the binary oxide was investigated.
Abstract: Nickel–cobalt oxides were prepared by coprecipitation of their hydroxides precursors and a following thermal treatment under a moderate temperature. The preformed nickel-cobalt bimetallic hydroxide exhibited a flower-like morphology with single crystalline nature and composed of many interconnected nanosheets. The ratio of Ni to Co in the oxides could easily be controlled by adjusting the composition of the original reactants for the preparation of hydroxide precursors. It was found that both the molecular ratio of Ni to Co and the annealing temperature had significant effects on their porous structure and electrochemical properties. The effect of the Ni/Co ratio on the pseudocapacitive properties of the binary oxide was investigated in this work. The binary metal oxide with the exact molar ratio of Ni:Co = 0.8:1 annealed at 300 °C, showing an optimum specific capacitance of 750 F/g. However, too high an annealing temperature would lead to a large crystal size, a low specific surface area, as well as a mu...
231 citations
TL;DR: In this paper, a novel SIHC, coupling a titanium dioxide/carbon nanocomposite (TiO2/C) anode with a 3D nanoporous carbon cathode, which are both prepared from metal-organic frameworks (MOFs, MIL-125 (Ti) and ZIF-8, respectively), is designed and fabricated.
Abstract: Sodium-ion hybrid capacitors (SIHCs) can potentially combine the virtues of high-energy density of batteries and high-power output as well as long cycle life of capacitors in one device. The key point of constructing a high-performance SIHC is to couple appropriate anode and cathode materials, which can well match in capacity and kinetics behavior simultaneously. In this work, a novel SIHC, coupling a titanium dioxide/carbon nanocomposite (TiO2/C) anode with a 3D nanoporous carbon cathode, which are both prepared from metal-organic frameworks (MOFs, MIL-125 (Ti) and ZIF-8, respectively), is designed and fabricated. The robust architecture and extrinsic pseudocapacitance of TiO2/C nanocomposite contribute to the excellent cyclic stability and rate capability in half-cell. Hierarchical 3D nanoporous carbon displays superior capacity and rate performance. Benefiting from the merits of structures and performances of anode and cathode materials, the as-built SIHC achieves a high energy density of 142.7 W h kg(-1) and a high power output of 25 kW kg(-1) within 1-4 V, as well as an outstanding life span of 10 000 cycles with over 90% of the capacity retention. The results make it competitive in high energy and power-required electricity storage applications.
225 citations