Oxide Co3O4 Research Articles

Interfacial synergy between Pt3Co nanoparticles and CoO for efficient ammonia borane hydrolysis

Ammonia borane (AB, NH3BH3) with the high H2 content has been regarded as a promising material for chemical hydrogen storage. AB can hydrolyze to release H2 under the catalysis of noble-metal catalysts with high activity, but the high cost of noble-metals and their poor long-term stability prohibit the large-scale applications. Developing more cost-effective and stable catalysts by introducing cheap transition metal elements has been a promising strategy. Herein, we adopted a step-by-step precipitation method to synthesize bimetallic Pt-Co catalysts supported on rutile TiO2, which show significantly improved performance in AB hydrolysis reaction. The optimized 0.9Pt3.5Co/TiO2 catalyst (with the Pt and Co loadings of 0.9 and 3.5 wt%, respectively) exhibits an extremely high H2 generation rate, showing a turnover frequency value of 2163 molH2 molPt-1 min−1 at 298 K, 9 times higher than that of 0.9Pt/TiO2 catalyst and superior to those of most of the reported Pt-based catalysts. Structure characterizations and theoretical calculations reveal that the promoted AB hydrolysis performance arises from the interfacial synergistic effect between the supported Pt3Co alloy and cobalt oxide CoO, which accelerates the B-H bond cleavage and water activation, respectively. The excellent AB hydrolysis performance of the Pt-Co catalysts indicates the great prospects of alloy-oxide interfaces in the field of liquid phase chemical hydrogen storage.

A review on Co3O4 nanostructures as the electrodes of supercapacitors

Usage of supercapacitors in energy storage applications has now become a new trend due to their auspicious features. The introduction of pseudocapacitance has increased its weightage to be used in a greater number of practical applications. Electrodes are the major constituents of a supercapacitor, based on which the electrochemical performance of the supercapacitor is decided. Among the varieties of electrode materials available, transition metal oxides are the most suitable ones to fulfill the required criteria. Due to the occurrence of faradic redox reactions on the surface of electrodes, the selection of efficient and favorable electrode material plays a major role. Co3O4 (cobalt (III) oxide) is one of the most desirable electrode materials due to its various peculiar features. This paper reviews briefly several factors of Co3O4 as electrode material in supercapacitor applications. It includes comparative discussions towards different synthesize methodologies and the influence of its dimensional morphology on the electrochemical outputs like specific capacitance, energy density, and power density.

Effect of Zn Doping on Structure and Electrical Properties in Co3O4/Zn Nanocomposites with Different Morphology

AbstractTwo different comparatively simple methods were used to synthesize Co3O4/Zn nanocomposites in the form of nanoparticles and nanofibers with a Zn content of 0 to 33 mol%. It is shown that composites in the form of nanoparticles are a ZnxCo3‐xO4 solid solution having a spinel structure. Samples in the form of nanofibers, starting with a concentration of zinc atoms of 20 mol% and higher, in addition to the spinel structure, also contain crystalline zinc oxide ZnO. It has been established that the conductivity of composites of both types increases by 4–5 orders of magnitude upon the introduction of Zn atoms. The increase in conductivity is explained by the incorporation of zinc atoms into the crystal lattice of cobalt oxide spinel. The optimal content of zinc atoms, at which the samples have the highest conductivity, has been determined. The ability to control the conductivity of cobalt oxide Co3O4 both in the form of nanoparticles and in the form of nanofibers by introducing Zn atoms has been demonstrated. The results obtained make it possible to understand the features of electric transport in such low‐dimensional systems, and are also of interest for various practical applications, in particular, gas sensors and catalytically active materials.

Epitaxial Growth of Cobalt Oxide Thin Films on Sapphire Substrates Using Atmospheric Pressure Mist Chemical Vapor Deposition

This study demonstrated the epitaxial growth of single-phase (111) CoO and (111) Co3O4 thin films on a-plane sapphire substrates using an atmospheric pressure mist chemical vapor deposition (mist-CVD) process. The phase structure of the grown cobalt oxide films was manipulated by controlling the growth temperature and process ambient, confirmed through X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. Furthermore, the electrical properties of Co3O4 films were significantly improved after thermal annealing in oxygen ambient, exhibiting a stable p-type conductivity with an electrical resistivity of 8.35 Ohm cm and a carrier concentration of 4.19 × 1016 cm−3. While annealing CoO in oxygen atmosphere, the Co3O4 films were found to be most readily formed on the CoO surface due to the oxidation reaction. The orientation of the atomic arrangement of formed Co3O4 was epitaxially constrained by the underlying CoO epitaxial layer. The oxidation of CoO to Co3O4 was largely driven by outward diffusion of cobalt cations, resulting in the formation of pores in the interior of formed Co3O4 films.

Morphological features of Co3O4 nanoparticles obtained by solution combustion method

The global environmental crisis has made it imperative to enhance tools and techniques for monitoring and analyzing environmental parameters. Gas sensors, crucial for air quality assessment, continually under go technological advancements to enhance accuracy and efficiency in detecting harmful substances. They play an essential role in ensuring safety in workplaces, urban areas, and industries, aiding pollution control efforts. Enhanced gas sensor performance hinges on careful selection and control of gas-sensitive materials and their structure. This involves optimizing gas-sensitive compounds, employing advanced materials, and developing technologies for sensitive and rapid substance detection. One promising compound for this purpose is Co3O4 oxide, synthesized efficiently using the solution combustion method. This method off ers simplicity and allows for precise control over product structures and properties, enabling customization for specific requirements and ensuring high detection efficiency and accuracy. In this study, Co3O4 particles were synthesized from a mixture of cobalt nitrate and glycine with the addition of nitric acid using the solution combustion method. The influence of nitric acid addition and the fuel-to-oxidizer ratio on the morphological characteristics of the cobalt oxide was investigated. The results from SEM, TEM, XRD, and SAXS analyses confi rmed that the addition of nitric acid and a fuel-rich mixture lead to nanoparticles with smaller diameter spread and more stable characteristics.

Preparation, Characterization, Dielectric Properties, and AC Conductivity of Chitosan Stabilized Metallic Oxides CoO and SrO: Experiments and Tight Binding Calculations.

Polymeric films made from chitosan (CS) doped with metal oxide (MO = cobalt (II) oxide and strontium oxide) nanoparticles at different concentrations (5, 10, 15, and 20% wt. MO/CS) were fabricated with the solution cast method. FTIR, SEM, and XRD spectra were used to study the structural features of those nanocomposite films. The FTIR spectra of chitosan showed the main characteristic peaks that are usually present, but they were shifted considerably by the chemical interaction with metal oxides. FTIR analysis of the hybrid chitosan-CoO nanocomposite exhibited notable peaks at 558 and 681 cm-1. Conversely, the FTIR analysis of the chitosan-SrO composite displayed peaks at 733.23 cm-1, 810.10 cm-1, and 856.39 cm-1, which can be attributed to the bending vibrations of Co-O and Sr-O bonds, respectively. In addition, the SEM graphs showed a noticeable morphological change on the surface of chitosan, which may be due to surface adsorption with metal oxide nanoparticles. The XRD pattern also revealed a clear change in the crystallinity of chitosan when it is in contact with metal oxide nanoparticles. The presence of characteristic signals for cobalt (Co) and strontium (Sr) are clearly shown in the EDX examinations, providing convincing evidence for their incorporation into the chitosan matrix. Moreover, the stability of the nanoparticle-chitosan coordinated bonding was verified from the accurate and broadly parametrized semi-empirical tight-binding quantum chemistry calculation. This leads to the determination of the structures' chemical hardness as estimated from the frontier's orbital calculations. We characterized the dielectric properties in terms of the real and imaginary dielectric permittivity as a function of frequency. Dielectric findings reveal the existence of extensive interactions of CoO and SrO, more pronounced for SrO, with the functional groups of CS through coordination bonding. This induces the charge transfer of the complexes between CoO and SrO and the CS chains and a decrease in the amount of the crystalline phase, as verified from the XRD patterns.

Morpho-physiological growth performance and anti-oxidative capabilities of Acacia jacquemontii and Acacia nilotica upon exposure to Co3O4 Nbs in lead-contaminated soil

Immense crowd of heavy metal in cultivated land is evolving as a global concern as a result of boosted level of soil toxicity. Amongst various metals, Lead (Pb) contamination has become alarming for plant and human heath through ingesting of polluted soils and food crops. To counterfeit this, a nanotechnological neutralizer effective in form of soiling of cobalt oxide Co3O4 Nbs to Acacia jacquemontii and Acacia nilotica with various meditations as 25, 50, 75 and 100 ppm). A Substantial result was observed on growth of plants but premium results were got by applications of cobalt oxide Nbs at 75 ppm. By this means, enhanced root length (39%), fresh weight (32%), shoot length (58%), as well as dry weight (28%) in selected Acacia species compared to control. Chlrophy contents in A. jacquemontii were estimated to be 0.23, 2.73 and 3.19 mg/L with treated with different concentrations of cobalt Nbs while in A. nilotica, the contents were 0.51, 2.93 and 3.12 mg/L respectively on same concentration. The atomic absorption (AAS), antioxidant activity and defendable positive comeback by using Co3O4 Nbs. Hence, the greenly synthesized Co3O4 Nbs counter acts lead toxicity to override and preserving the growth of plant. Such nanotechnological kits can consequently enhance the alternative system to stunned toxicity for distinguish the yield demand end to end with the progress of agronomic management approaches.

Assessment of Oxidative Stress by Detection of H2O2 in Rye Samples Using a CuO- and Co3O4-Nanostructure-Based Electrochemical Sensor

Hydrogen peroxide is essential for biological processes and normally occurs in low concentrations in living organisms. However, exposure of plants to biotic and abiotic stressors can disrupt their defense mechanisms, resulting in oxidative stress with elevated H2O2 levels. This oxidative stress can damage cell membranes, impair photosynthesis, and hinder crucial plant functions. The primary focus of this article is to investigate the effects of salt and herbicide stress factors on the growth of rye samples. For precise quantification of the released H2O2 concentration caused by these stress factors, a non-enzymatic electrochemical sensor was developed, employing nanostructured CuO and Co3O4 oxides. Nanostructured electrodes exhibit high sensitivity and selectivity towards H2O2, making them suitable for detecting H2O2 in real samples with complex compositions. Rye samples exposed to NaCl- and glyphosate-induced stress demonstrated notable concentrations of released H2O2, displaying an increase of up to 30% compared to the control sample. Moreover, optical absorption measurements revealed a substantial decrease in chlorophyll concentration (up to 35% compared to the control group) in rye samples where elevated H2O2 levels were detected through electrochemical methods. These findings provide further evidence of the harmful effects of elevated H2O2 concentrations on plant vital functions.

Exceptionally active and stable RuO2 by constructing p-n heterojunction between Co3O4 and RuO2 for acidic water oxidation

Development of Ru-based electrocatalysts for acidic oxygen evolution reaction without a trade-off between activity and durability remains challenging. Herein, we constructed Co3O4/RuO2 heterojunctions anchored on carbon (Co3O4/RuO2-C) with a low Ru loading (2.74 wt%), in which strong coupled p-n junctions facilitated electron transfer from RuO2 to Co3O4. The Co3O4/RuO2-C demonstrated a low overpotential of 170 mV at 10 mA cm−2 and long-term stability in 0.1 M HClO4 due to its unique structure. The origin of its high performance in acidic OER was revealed by the combination of in-situ attenuated total reflection infrared and Raman tests. Concretely, oxygen generation for Co3O4/RuO2-C was dominated by the adsorbate evolution mechanism, and the introduction of Co3O4 facilitated the redox of RuO2, generating active sites for OER. Theoretical calculations further substantiated that the Co3O4/RuO2 heterojunctions possessed lower energy barriers for OER. This work provides a compelling synthesis route for effective and stable electrocatalysts for acidic OER.

Reducibility of Al3+-Modified Co3O4: Influence of Aluminum Distribution.

The reduction of Co-based oxides doped with Al3+ ions has been studied using in situ XRD and TPR techniques. Al3+-modified Co3O4 oxides with the Al mole fraction Al/(Co + Al) = 1/6; 1/7.5 were prepared via coprecipitation, with further calcination at 500 and 850 °C. Using XRD and HAADF-STEM combined with EDS element mapping, the Al3+ cations were dissolved in the Co3O4 lattice; however, the cation distribution differed and depended on the calcination temperature. Heating at 500 °C led to the formation of an inhomogeneous (Co,Al)3O4 solid solution; further treatment at 850 °C provoked the partial decomposition of mixed Co-Al oxides and the formation of particles with an Al-depleted interior and Al-enriched surface. It has been shown that the reduction of cobalt oxide by hydrogen occurs via the following transformations: (Co,Al)3O4 → (Co,Al)O → Co. Depending on the Al distribution, the course of reduction changes. In the case of the inhomogeneous (Co,Al)3O4 solid solution, Al stabilizes intermediate Co(II)-Al(III) oxides during reduction. When Al3+ ions are predominantly on the surface of the Co3O4 particles, the intermediate compound consists of Al-depleted and Al-enriched Co(II)-Al(III) oxides, which are reduced independently. Different distributions of elemental Co and Al in mixed oxides simulate different types of the interaction phase in Co3O4/γ-Al2O3-supported catalysts. These changes in the reduction properties can significantly affect the state of an active component of the Co-based catalysts.

Improving benzene catalytic oxidation on Ag/Co3O4 by regulating the chemical states of Co and Ag

Silver (9 wt.%) was loaded on Co3O4-nanofiber using reduction and impregnation methods, respectively. Due to the stronger electronegativity of silver, the ratios of surface Co3+/Co2+ on Ag/Co3O4 were higher than on Co3O4, which further led to more adsorbed oxygen species as a result of the charge compensation. Moreover, the introducing of silver also obviously improved the reducibility of Co3O4. Hence the Ag/Co3O4 showed better catalytic performance than Co3O4 in benzene oxidation. Compared with the Ag/Co3O4 synthesized via impregnation method, the one prepared using reduction method (named as AgCo-R) exhibited higher contents of surface Co3+ and adsorbed oxygen species, stronger reducibility, as well as more active surface lattice oxygen species. Consequently, AgCo-R showed lowest T90 value of 183°C, admirable catalytic stability, largest normalized reaction rate of 1.36 × 10−4 mol/(h·m2) (150°C), and lowest apparent activation energy (Ea) of 63.2 kJ/mol. The analyzing of in-situ DRIFTS indicated benzene molecules were successively oxidized to phenol, o-benzoquinone, small molecular intermediates, and finally to CO2 and water on the surface of AgCo-R. At last, potential reaction pathways including five detailed steps were proposed.

Synthesized Fe-doped Co3O4 nanoparticles-based anode for high-performance lithium-ion batteries application

ABSTRACT Co3O4 has been considered a promising anode material because of its high theoretical capacity (890 mAh/g) and remarkable energy density. Unfortunately, it suffers from low initial coulombic efficiency, rapid capacity fading, poor electronic conductivity, large volume changes, and aggregation during the lithium ion intercalation/deintercalation process. In this work, a series of Fe2+-doped Co3O4 nanostructured materials Co3(1-x)Fe3xO4 (x = 0, 0.01, 0.02 and 0.03) were produced by a simple chemical co-precipitation method. The Fe doping led to a slight increase of the lattice parameter, which is beneficial to the rapid diffusion of Li+ ion during the lithiation/delithiation process. Meanwhile, the Fe-doped Co3O4 sample exhibited an excellent rate capability of 886.47 mAh/g at 500 mA/g, and outstanding cyclic stability (1156.91 mAh/g for 50 cycles, with the capacity retention rate of 83.53% at the current density of 100 mA/g), demonstrating improved electrochemical performance, compared with that of pure Co3O4. The good electrochemical performance profited from the formation of oxygen vacancies by Fe doping, which provided more space for Li+ diffusion and improved the electronic conductivity of the anode material. This work provides a simple way to improve the comprehensive electrochemical performance of the transitional metal oxide Co3O4 anode electrodes for lithium-ion batteries.

Nonuniformity of magnetization processes of a cobalt-based amorphous alloys in the as-quenched state

The magnetization processes nonuniformity of an amorphous cobalt-based soft-magnetic alloy AMAG-172 (Co-Ni-Fe-Cr-Mn-Si-B) in the as-quenched state were studied. Studies have shown that the main reason of the magnetic characteristics and magnetization processes nonuniformity is the nonuniformity of internal stresses due to the alloy manufacture method. An indirect characteristic of internal stresses is the domains volume with orthogonal magnetization. The observed bimodal field dependence of the magnetic permeability and the field shift of the hysteresis loops in the region of 180-degree domain walls displacement are a consequence of the nonuniformity of the alloy over its thickness. The field shift and the asymmetry of hysteresis loops are explained in terms of the formation of a unidirectional exchange anisotropy at the interface between the ferromagnetic and antiferromagnetic phases of the planar magnetization components oriented along the ribbon axis. The field shift disappearance and the asymmetry of the hysteresis loops along the width of the tape can be interpreted as a decrease in the thickness of the CoO oxide antiferromagnetic layer due to the difference in the concentrations and depth of oxygen and hydrogen atoms penetration induced into the surface of the tape during the manufacture of the tape as a result of interaction with atmospheric vapor.

The selective site occupation, structural and thermal stability of high entropy (CoCrFeMnNi)3O4 spinel

The selective site occupation may occur in high entropy spinel oxide (HESO), which is essential for the structural and thermal stability. A single-phase (Co0.2Cr0.2Fe0.2Mn0.2Ni0.2)3 O4 was therefore investigated to reveal its high stability in a wide temperature from room temperature to 1400°C in air/nitrogen. Characteristic features and DFT calculations proved the derived structural model, [Fe0.5Co0.5]Td [Co0.1Fe0.1Cr0.6Mn0.6Ni0.6]Oh O4, which highlighted the selective site occupation in HESO. The real structure presented here provides an alternate viewpoint on the cationic arrangement in HESO, which presented low crystal field stable energy value (−25.74 Dq) and low formation energy (−5.884 eV/atom). The HESO exhibited a low weight loss of 1.68 wt% at 1400 °C in nitrogen, which was 42.86 % lower than nickel ferrite spinel. No precipitation or decomposition was observed in the single-phase HESO in air. However, since the Gibbs free energy change of possible precipitation reactions of NiO and CoO oxides were negative below 1594 K, the precipitation of rock-salt phase close to (NiCo)1-δ could be observed in nitrogen due to oxygen deficiency.

Exceptionally stable CePO4 and RuO2 contributing to catalytic oxidation of 1,2-dichloroethane on Co3O4 catalysts: Complete inhibition of chlorinated byproducts

Highly toxic, reactive and refractory chlorinated VOCs (Cl-VOCs) is urgent for purification by the most favoured catalytic oxidation technique, however, the formation of polychlorinated byproducts is huge obstacle for most catalysts. Here, nanorods assembled monoclinic CePO4 microspheres were synthesized and used as the support of highly active but low-selective Co3O4 for catalytic oxidation of Cl-VOCs. The prepared Co3O4/CePO4 using ascorbic acid (AA) as a chelating agent presented a high activity and low selectivity of vinyl chloride (VC) for catalytic oxidation of 1,2-dichloroethane (DCE) due to the high dispersion of Co3O4, compared with bulk Co3O4 and Co3O4/SiO2, possible polychlorinated byproducts were completely inhibited in the presence of CePO4 support. The co-introduction of RuO2 further suppressed the formation of VC as a representative dechlorinated byproduct owing to the enhanced redox ability and migration of surface lattice oxygen, below 0.5% VC selectivity was detected on the optimized RuCoOx/CePO4 and completely disappeared above 275 °C. Moreover, RuCoOx/CePO4 also revealed the superior versatility, durability and thermal stability as well as the outstanding resistance to CO2, H2O and sulfur. The restraint of polychlorinated byproducts also can be achieved by other phosphates besides CePO4 and attributed to the strong coordination effect and electron-withdrawing function of PO43-. This work was contributed to further understand the inhibition of chlorinated byproducts for catalytic oxidation of Cl-VOCs and rationally design full-featured catalysts.

Multi-hierarchical heterostructure of GO/ NiCo2O4/Co3O4 for high power lithium-ion batteries

The application of high-rate lithium-ion batteries (LIBs) has been impeded by the sluggish kinetics, poor conductivity and volumetric expansion of anode materials. Rational design of the anode materials is essential for the rate performance of LIBs. Herein, a multihierarchical heterostructure composite composed of graphene oxide (GO)nanosheets, NiCo2O4 nanorods and Co3O4 nanocubes was synthesized via a self-template method. Owing to the elaborate nanostructure and synergy of the components, the anode attained favorable kinetics, structural stability and high conductivity and delivered a reversible capacity of 1283 mA h g−1 at 0.2 A g−1, an impressive rate capacity of 649.1 mA h g−1 at 10 A g−1 and a long-term cycle performance with a capacity of 857 mA h g−1 retained after 1100 cycles at 1 A g−1. Furthermore, the full cell assembled with the as-prepared anode and commercial cathode also delivered a high-rate capacity of 72 mA h g−1 at 1 A g−1 and a remarkable capacity retention of 92.3% after 100 cycles, demonstrating the promising potential of the anode in practical high-power LIBs.

Peculiar Features of Formation of the Phase Composition of Black Clinker Ceramics

This paper examines the peculiarities of the phase composition of black clinker bricks based on the ceramic masses of Kerameya enterprise (Sumy, Ukraine). The principles of charge choice are given considering the ratio of coloring oxides Fe2O3, CoO, MnO2, Mn3O4 and CuO. We found that the phase composition of black clinker bricks after firing at 1100 °С is mainly represented by quartz, microcline, mullite, residues of biotite, as well as hematite and hausmannite as the coloring phases, and also small amounts of cuprite. To produce black ceramic bricks on the basis of clay composition, we need to take 13.5 wt% elements with the ratio of Mn: Fe: Ti: Cu equal to 4.2: 7.7: 0.5: 1.1. Such ceramic mass is already used to produce ceramic clinker bricks with water absorption of 5%, mechanical compressive strength of more than 35 MPa and frost resistance of more than 150 freezing and thawing cycles.

Efficient antibacterial activity of ternary nanocomposites containing hydroxyapatite, Co3O4, and cerium oxide

Metal oxide nanoparticles are routinely utilized in the biomedical field due to their diverse functionality. In particular, hybrid nanocomposites containing metal oxides possess a significant tunability of their chemical properties, as well as modifiable grain size and morphology. Hydroxyapatite (HA) and graphene oxide (GO) are already widely used in bone tissue engineering. We hypothesized that the addition of cobalt oxide or cerium oxide to form a hybrid nanocomposite with HA and GO can further enhance their properties toward cell viability and biodegradability. In this work, cobalt oxide/cerium oxide were individually combined with HA and GO to fabricate a ternary nanocomposite - HA/Co3O4/GO and HA/CeO2/GO for its potential use as a bone replacement hybrid material. The crystal structure of the resulting HA/Co3O4/GO composite was elucidated with XRD. The surface composition of the composite was analyzed using X-ray Photoelectron Spectroscopy and complex surface speciation was observed and assigned to Co(OH)2 and Co3O4. The particle length of HA in the composite was 35.5 ± 7.0 nm while the particle size of the cubic Co3O4 was 49.3 ± 10.8 nm, as revealed in TEM images. The antibacterial properties of HA/CeO2/GO were measured with the resulting inhibition area for E. coli and S. aureus of 15.9 ± 0.3 mm and 16.4 ± 0.2 mm, respectively. The ternary composite of HA/CeO2/GO and HA/Co3O4/GO showed an improvement in hardness of 4.1 ± 0.2 GPa and 3.2 ± 0.2. Summarily, HA/Co3O4/GO exhibited improved porosity, cell viability, and biodegradability compared with pristine HA. Overall, HA/Co3O4/GO nanocomposite possessed a porous structure and showed excellent antibacterial properties as well as controlled biodegradability and can be proposed as an improved bone-implant biomaterial.

Obtaining of Metal-Matrix Alloys Based on Ni-Al for ESD Coatings Formation

The experimental results of obtaining complex-alloyed intermetallic alloys by the method of liquid-phase self-propagating high-temperature synthesis (SHS) and their subsequent use for the formation of wear-resistant coatings by the method of electrospark deposition (ESD) are submitted. Metal oxides Cr2O3, NiO, CoO and mineral concentrate containing a larger part of ZrO2 in its composition were used as a melt charge for the SHS experiments. Alloys based on Ni-Al system dopped with Cr, Zr, Co, and C were obtained. It was established that extra addition of C led to the refinement of the alloys microstructure (3-5 times). ESD coatings were formed on steel 45 using the obtained alloys as anode material. The coatings formed by using the alloys doped by Co, Zr, Cr and extra addition of C (0.4 wt%) proved to be maximum wear resistant.

Binder-free hybrid cobalt-based sulfide/oxide nanoarrays toward enhanced energy storage performance for hybrid supercapacitors

Cobalt-based materials have excellent electrochemical properties in theory and show great potential for improving the energy density of supercapacitors. The facile synthesis strategy and enhanced energy storage performance of self-supported cobalt-based sulfide/oxide nanoarrays (Co-S/Co-O) are demonstrated for hybrid supercapacitors in this work. In the Co-S/Co-O nanoarrays, the CoS sulfide and CoO oxide are intertwined with each other to form a whole, bringing positive synergistic effect for Faraday reaction and rapid electrons/ions transfer. As expected, Co-S/Co-O has higher specific capacity (1065 C g−1 at 1 A g−1) than CoS (176 C g−1) and CoO (702.5 C g−1). Furthermore, the Co-S/Co-O hybrid supercapacitor assembled with nitrogen-doped graphene as negative electrode shows higher specific capacitance (110 F g−1 at 1 A g−1) and specific energy (39.38 Wh kg−1 at a specific power of 800 W kg−1). The results show that Co-S/Co-O hybrid materials have great potential for energy storage applications. This work also provides a good strategy for improving the charge storage capacity of cobalt-based materials.