ZnCo2O4

Cobalt oxides, including spinel Co3O4 and rock-salt CoO, have been widely reported as promising catalysts for oxygen reduction reaction (ORR). However, three types of cobalt ions, i.e., Co2+ in the tetrahedral site (Co2+Td), Co3+ in the octahedral site (Co3+Oh) and Co2+ in the octahedral site (Co2+Oh), are included in these oxides, and the roles of cobalt geometric occupancy and valance states have remained elusive. Here, for the first time, we investigated the effects of cobalt geometric occupancy on the ORR activity by substituting Co2+Td and Co3+Oh of Co3O4 with inactive Zn2+ and Al3+, respectively...

Aiming to achieve metal-oxide-based electrodes for Li-ion batteries with enhanced energy density and cycling life, especially overcoming their negative volume expansion during cycling, more effort should be devoted to the exploration of the combination of morphology-controlled metal oxides with carbonaceous materials. In this work, we select dual/single-metallic organic frameworks immobilized on the surface of carbon nanotubes as the precursors to synthesize composites of ternary/single metal oxides with carbon nanotubes (ZnCo2O4@CNTs and ZnO@CNTs)...

The design of heterogeneous catalysts of high efficiency for complete oxidation of volatile organic compounds (VOCs) is a challenge. In the present study, propane is adopted as a VOC representative, and core-shell structured ZnCo2O4@CeO2 catalysts with Ce decoration were synthesized and tested for propane combustion. Through SEM, STEM, and EDX analyses, the structure of the ZnCo2O4@CeO2 catalysts was characterized. The results of activity evaluation demonstrate that the presence of Ce can significantly promote catalytic performance, and the most suitable Ce content has been verified...

Pure dielectric microwave absorbers with strong attenuation capability and wide-band response become a challenge for efficient electromagnetic wave energy absorption. Herein, a series of ZnCo2O4 hierarchical structures with superior absorption performance have been achieved by tuning their surface architectures from ball-, hydrangea- to cabbage-, and pineapple-like morphologies. A facile one-step synthesis strategy using a self-assembly process with ZnCo2O4 crystalline flakes as structural units was proposed...

In this work, ZnCo2 O4 @MnO2 core-shell structures are successfully prepared on nickel foam by a simple hydrothermal approach. The obtained core-shell structures exhibit excellent areal capacitance and cycling stability, which may be ascribed to the rational design of a hybrid-material based electrode structure that facilitates ion transport. The as-assembled supercapacitor device shows outstanding specific capacitance, demonstrating that ZnCo2 O4 @MnO2 core-shell structure is a candidate as a supercapacitor electrode material in flexible energy storage applications...

Electrochemical water splitting is a promising way for the sustainable production of hydrogen, but the efficiency of the overall water splitting reactions largely depends on the oxygen evolution reaction (OER) because of its sluggish kinetics. Herein, a series of hierarchical ZnCo2O4/Co3O4/NC-CNT mesoporous dodecahedrons with carbon-nanotubes grafting have been synthesized via sequential pyrolysis in nitrogen and mild oxidation in air from ZnCo-bimetallic zeolitic imidazolite frameworks (ZnCo-ZIF). The simultaneous modulation of oxygen vacancies, composition together with hierarchical mesoporous architecture remarkably enhanced their electronic conduction, the amount and reactivity of accessible actives, thus boosted their intrinsic activity in OER...

Designing core-shell electrode materials with desired components and architectures is a promising strategy for boosting electrochemical performance. Here, three-dimensional (3D) hierarchical ZnCo2O4@Ni(OH)2 core-shell nanosheet arrays have been successfully fabricated on Ni foam substrate, where the porous ZnCo2O4 nanosheet "core" as the conductive scaffold is synthesized by a metal-organic framework (MOF)-templated method, and ultrathin Ni(OH)2 nanoflakes "shell" with rich active sites are grafted on ZnCo2O4 nanosheet through a hydrothermal treatment...

Zeolitic imidazolate frameworks have stimulated great attention due to their potential applications in energy storage, catalysis, gas sensing, drug delivery etc. In this paper, the three-dimensional porous nanomaterial Co3O4/ZnCo2O4/CuO with hollow polyhedral nanocage structures and highly enhanced electrochemical performances was synthesized successfully by a zeolitic imidazolate framework-67 route. The composites hold the shape of the ZIF-67 templates well and the shell has multiple compositions. In the process, we first synthesized the nanostructure hydroxide precursors and then transformed them into the corresponding metal oxide composites by thermal annealing in air...

In this work, a series of three-dimensional porous flower-like zinc doped NiCo2 O4 (ZNCO) nanostructures with different Zn doping level are successfully prepared by a facile solvothermal process without using any templets. The obtained products are characterized by various techniques, and their electrocatalytic performances are also assessed by the oxygen evolution reaction (OER). According to the electrochemical characterization, it is demonstrated that ZNCO-0.15 (i.e., Zn0.15 Ni0.85 Co2 O4 ) nanoflowers show a lower overpotential, smaller Tafel slope, higher electrochemical active surface area (ECSA), as well as a larger turnover frequency (TOF) value than those of Co3 O4 , NiCo2 O4 , and ZnCo2 O4 nanoflowers, indicating that introduction of an optimal content of zinc ions plays an important role in enhancing electrocatalytic performances for OER...

In this work, we report a facile route to fabricate a ZnCo2O4 nanosheet derived from metal-organic frameworks. The as-prepared ZnCo2O4 nanosheet material for lithium-ion batteries shows an excellent electrochemical performance. The obtained ZnCo2O4 nanosheet delivers a high reversible capacity of 1640.8 mA h g-1 at a current density of 100 mA g-1 after 50 cycles. More importantly, even at a current density of 1500 mA g-1, the electrode material still exhibits a discharge capacity of 581.3 mA h g-1 after 190 cycles...

In this work, novel secondary assembled micro/nano porous spheres ZnCo2 O4 were firstly prepared by combining the hydrothermal method with post-synthesis calcinations. The structure and morphology of the obtained powder were characterized by x-ray powder diffraction and field emission-scanning electron microscopy. As the anode material of lithium-ion half-cells, the as-prepared ZnCo2 O4 delivered a very high capacity, extra cycling stability and excellent rate capability. A discharge capacity of 950 mAh g-1 with up to 99...

In allusion to traditional transition-metal oxide (TMO) anodes for lithium-ion batteries, which face severe volume variation and poor conductivity, herein a bimetal oxide dual-composite strategy based on two-dimensional (2D)-mosaic three-dimensional (3D)-gradient design is proposed. Inspired by natural mosaic dominance phenomena, Zn1-x Cox O/ZnCo2 O4 2D-mosaic-hybrid mesoporous ultrathin nanosheets serve as building blocks to assemble into a 3D Zn-Co hierarchical framework. Moreover, a series of derivative frameworks with high evolution are controllably synthesized, based on which a facile one-pot synthesis process can be developed...

Aiming at promoting the photocatalytic performance of spinel oxides, an efficient method of constructing hollow porous zinc cobaltate (Znx Co3- x O4 ) nanocubes was established in this work. Bimetallic zeolitic imidazolate frameworks (ZIFs) were prepared through a facile self-assembly strategy, then hollow Znx Co3- x O4 nanocubes were obtained by calcining the bimetallic ZIFs precursor. The structural features and optical properties of the Znx Co3- x O4 nanocubes were comprehensively investigated by a series of characterization techniques...

Hollow octahedral ZnCo2 O4 nanocages assembled from ultrathin 2D nanosheets are prepared through facile fast simultaneous coordinating etching and thermal processes. Electrochemical results show that the hollow octahedral ZnCo2 O4 nanocage is an outstanding anode material for LIBs with a high reversible discharge capacity of 1025 mA h g-1 at 500 mA g-1 after 200 cycles, and an outstanding rate capability of 525 mA h g-1 at 4 A g-1 . Moreover, this simple, low cost and fast process could be useful for the construction of many other hollow advanced materials for supercapacitors, sensors and other novel energy and environmental applications...

Aluminum-air battery is a promising candidate for large-scale energy applications because of its low cost and high energy density. Remarkably, tremendous efforts have been concentrated on developing efficient and stable cathode electrocatalysts toward the oxygen reduction reaction. In this work, a hydrothermal-calcination approach was utilized to prepare novel reduced graphene oxide (rGO)-supported hollow ZnO/ZnCo2 O4 nanoparticle-embedded carbon nanocages (ZnO/ZnCo2 O4 /C@rGO) using a zeolitic imidazolate framework (ZIF-67)/graphene oxide/zinc nitrate composite as the precursor...

Herein, a novel heterostructure was fabricated by combining electrochemically and optically active materials to achieve a high capacitive response of 896 F g-1 at 5 A g-1 . A network of ZnCo2 O4 nanorods (NRs) was directly grown on a three-dimensional matrix of H : ZnO NRs (ZnCo2 O4 /H : ZnO NRs) that offered synergistic advantages by providing an optimum ion/charge transportation path, large electrochemically active surface area, and stable capacitive response during the electrolytic process. Furthermore, the fabricated solid-state asymmetric supercapacitor ZnCo2 O4 /H : ZnO NRs//activated carbon induced a large potential window of 1...

To achieve the rational design of nanostructures for superior gas sensors, the ultrasmall nanoparticles (NPs) loaded on ternary metal oxide (TMO) hollow spheres (HS) were synthesized by using the polystyrene (PS) sphere template and bimetallic metal-organic framework (BM-MOFs) mold. The zinc and cobalt based zeolite imidazole frameworks (BM-ZIFs) encapsulating ultrasmall Pd NPs (2-3 nm) were assembled on PS spheres at room temperature. After calcination at 450 °C, these nanoscale Pd particles were effectively infiltrated on the surface of ZnO/ZnCo2 O4 HSs...

Hierarchical ZnCo2O4@Ni(OH)2 sheet composite structures on Ni foam were rationally designed and successfully synthesized. The ZnCo2O4 micro-sheets grown on Ni foam served as the skeleton to improve the electrical conductivity of redox active Ni(OH)2 materials, providing more electroactive sites for the faradaic reaction, and solidify the Ni(OH)2 materials onto Ni foam as a current collector. The electrode of ZnCo2O4@Ni(OH)2 showed an ultrahigh areal capacitance of 4.6F/cm(2) at a current density of 2mA/cm(2)...

In this paper ZnCo2 O4 nanowall arrays (NWAs) were first obtained through self-assembly followed by calcination. Then atomic layer deposition was used to fabricate core-shell ZnCo2 O4 @TiO2 NWAs as anode materials for lithium ion batteries (LIBs). The hierarchical NWA nanostructure has fast ion diffusion and electron transport at the electrode/electrolyte interface, while the excellent chemical stability of the TiO2 shell can protect the ZnCo2 O4 NWAs from volume expansion during the charge and discharge processes...

The growth of ultrathin ZnCo2 O4 nanosheets on reduced graphene oxide (denoted as rGO/ZnCo2 O4 ) via a facile low-temperature solution method combined with a subsequent annealing treatment is reported. With the assistance of citrate, interconnected ZnCo2 O4 nanosheets can assemble into hierarchically porous overlays on both sides of rGO sheets. Such a hybrid nanostructure would effectively faciliate the charge transport and accommodate volume variation upon prolonged charge/discharge cycling for reversible lithium storage...