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In this paper, Co3O4 nanoparticles and Co3O4 modified reduced graphene oxide (Co3O4/rGO) are successfully elaborated by hydrothermal method and used as anode materials in lithium-ion batteries. The structure, composition, and morphology of the hydrothermal powders are characterized by XRD, Raman spectroscopy, SEM, and TEM while their electrochemical performance was evaluated using cyclic voltammetry and galvanostatic charge/discharge studies. The Co3O4/rGO anode exhibit improved electrochemical performance in terms of specific capacity, reversibility and stability compared to single-component Co3O4. At 0.1 A g−1, the specific charge/discharge capacity for the pure Co3O4 is 855 mAh g−1 and 850 mAh g−1 respectively, while for Co3O4/rGO composite is about 1198 mAh g−1 and 1285 mAh g−1 respectively. It is found that the conductivity values increase with adding of the rGO from 4.4 × 10−4 Ω cm for the Co3O4 to 4.5 × 105 Ω cm for Co3O4/rGO composite. The improvement in the electrochemical capacity of the composite anode is mainly ascribed to a cooperative effect between the rGO with good electrical conductivity and the unique nano-sized Co3O4 with a short diffusion pathway for lithium ions diffusion. [ABSTRACT FROM AUTHOR]

Because surface oxygen has the extraordinary capacity to act as an electron donor to explosive compounds that lack electrons; cobalt oxide may have potential catalytic properties. Using hydrothermal processing, highly crystalline, dispersed cobalt oxide nanoparticles (NPs) of 23.5 nm were created. HMX (1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocane) energetic matrix was re-precipitated with anti-solvent assistance while cobalt oxide NPs were present, re-dispersed in organic solvent, and integrated. With a 53% increase in HMX decomposition enthalpy measured by DSC, cobalt oxide NPs showed higher catalytic activity. Cobalt oxide nanoparticles exhibited a 1550 J/g compared to HMX 1016 J/g. Using the Kissinger and KAS models, cobalt oxide NPs showed a 41% and 37% decrease in HMX apparent activation energy, respectively. Colloidal cobalt oxide NPs could be easily made and integrated into HMX, withstanding high interfacial surface area and superior catalytic performance. The study suggests a potential strategy for creating new, and more effective catalysts for the thermal degradation of HMX. [ABSTRACT FROM AUTHOR]

This research article provides the synthesis and characterization of Cobalt Oxide nano particles by eco-friendly green chemistry method. The cobalt oxide nano particles were synthesised by using leaf extract of Hibiscus rosa-sinensis. The light violet coloured leaf extract of hibiscus rosa-sinensis was used as catalyst and stabilizer for the synthesis of nano particles from precursor cobalt chloride hexa hydrate. So obtained cobalt oxide nano particles were characterized by EDAX, SEM, XRD, FTIR, TGA. EDAX confirms the presence of cobalt and oxygen in the nano particles. SEM studies shows the sponge and few cubical spine like structure of cobalt oxide with average grain size of 60 nm. XRD studies confirms the nano size of particles and maximum peak was obtained at (311) confirms the presence of nano cobalt oxide. [ABSTRACT FROM AUTHOR]

This study aims to appraise the antioxidant, anti-diabetic, and anti-inflammatory accomplishments of green synthesized cobalt oxide nanoparticles (Co3O4 NPs) mediated by Bauhinia racemosa leaves. Bauhinia racemosa is commonly called ''Thiruvachi' leaf tree in Tamil. The green synthesized Co3O4 NPs are calcinated at 350 °C, then characterized by TG/DTA, UV, FTIR, FL, XRD, DLS, SEM with EDS analysis, TEM, and Supercapacitor performance studies with CV analysis. TGA/DTA result associated with weight loss and exothermic reaction due to desorption of chemisorbed water. FTIR was performed to identify the functional groups of carbonyl, hydroxyl, amine, and protein molecules, which form a layer covering Co3O4 NPs and stabilize the Co3O4 NPs in the medium. The XRD pattern peaks are associated with a poly cubic crystalline form of metallic cobalt oxide nanoparticles. The average grain size of Co3O4 NPs is 36.45 nm. This research focused on Biological studies like antioxidant, anti-diabetic, and anti-inflammatory, total antioxidant measured by phosphomolyptenium reagent with vitamin C as the standard, Anti-diabetics studies carried out by α-amylase inhibition method and anti-inflammatory bustle followed by BSA denaturation technique. The spectral and morphological data confirms the Co3O4 NPs formation. The anti-inflammatory activity showed good results than the antioxidant and anti-diabetic activity. [ABSTRACT FROM AUTHOR]

Herein, the cobalt oxide thin films are elaborated by spray pyrolysis technique. The effect of temperature of substrates on several properties of cobalt oxide is studied. The thin layers are characterized by using X‐ray diffraction (XRD), Raman spectrometry (RS), and UV–vis spectrophotometer. The XRD analysis shows that Co3O4 thin layers have been formed along <111> preferential orientation. The RS displays the characteristic vibration modes of cobalt oxide phase, which confirms the formation of a single phase of spinel Co3O4 thin layers. The UV–vis spectrophotometer allows us to investigate the optical properties such as the absorbance, the transmittance, and the optical bandgap. The variation of electrical properties with the variation of temperature deposition confirms the high impact of the effect that study to make the cobalt oxide an important candidate for gas sensor devices. [ABSTRACT FROM AUTHOR]

Cobaltite spinel oxides (CuCo2O4), which show electrocatalytic activity for oxygen evolution reaction (OER), are readily synthesized using a facile hydrothermal method, with a stationary ratio, uniform flower-like mesopores morphology, and high crystallinity. We have carried out first-principles calculations on the mechanism of the reaction pathway and the Gibbs free energy diagram of CuCo2O4 structures using density functional theory and purely confirmed by experimental results. This catalyst performed an outstanding OER performance with an overpotential 230 mV at 10 mA cm−2 in 1 M KOH, which was close to IrO2 with an overpotential 190 mV at 10 mA cm−2. This work provides a facile method for electrocatalytic oxygen production with enhanced conductivity and enhanced OER by replacing cobalt with copper. [ABSTRACT FROM AUTHOR]

The fabrication of a heteroatom-doped nanocomposite based on cobalt oxide modified sulfur, phosphorus co-doped carbon nitride (Co3O4/SP-CN) with increased active sites is reported. The synthesized nanocomposite offers surprisingly high electrocatalytic oxidation efficacy toward human albumin (HA) despite its agglomeration. This improved efficacy of Co3O4/SP-CN nanocomposite could be attributed to its increased adsorption sites and surface defects, fast charge transportation capability, and conductivity. Additionally, morphological and compositional analysis of the fabricated Co3O4/SP-CN material has been performed through scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photon spectroscopy (XPS), and Raman spectroscopy. The fabricated electrode shows remarkable amperometric response against the HA with a limit of detection of 8.39 nM and linear range of 20–4000 nM at applied potential of 0.25 V versus Ag/AgCl in 0.1 M PBS (pH 8.2). The designed Co3O4/SP-CN electrode has been successfully applied to monitor HA in urine samples of diabetic patient with recovery percentage from 94.1 and 92.1% and with relative standard deviation (RSD) values of 5.8 and 7.8%. According to the best of our knowledge, this is the first report to use a Co3O4/SP-CN–based graphitic pencil (GP) electrode for monitoring of HA for early diagnosis of diabetic nephropathy. [ABSTRACT FROM AUTHOR]

Spinel cobalt oxide nanoflakes supported on graphene oxide nanosheets (GO-supported Co3O4) was fabricated via a two-step procedure as a high-performance pseudocapacitive electrode. In the first step, graphene oxide (GO) nanosheets were uniformly deposited on the surface of graphite current collector by electrophoretic deposition (EPD) technique to construct a three-dimensional (3D) conductive GO framework. In the following, cobalt oxide nanoflakes were electrochemically deposited on the surface of GO nanosheets. The structure and morphology of the as-prepared GO-supported Co3O4 hybrid electrode were examined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FESEM). Considering that the obtained 3D open porous structure can effectively facilitate electrons and electrolyte ions transport to the active material, the hybrid electrode exhibits excellent charge storage characteristics including a high specific capacitance of 765 F g−1 at 1 A g−1, good rate capability (62.4% capacitance retention with a tenfold increase in the discharge current density), and superior cycling stability (91.9% of the initial discharge capacitance after 2000 cycles). [ABSTRACT FROM AUTHOR]

Electrical discharges in liquids are considered an efficient and ecological technique of nanoparticle synthesis via controlled erosion of electrodes. Herein, we use spark discharges between Co–Co, Ni–Ni, Co–Ni, or Ni–Co electrodes immersed in distilled water to synthesize Co and/or Ni nanoparticles, as well as their oxides. When mixed electrodes are used (Co–Ni or Ni–Co), both Co and Ni nanoparticles are produced, and the major species is dictated by the nature of the anode pin. The characteristics of nanoparticles synthesized under varying conditions of pulse width (100 and 500 ns) and voltage amplitude (5 and 20 kV) are analyzed by transmission electron microscopy. Within the investigated discharge conditions, it is not possible to produce Co–Ni nanoalloys; however, core–shell nanoparticles are observed among the Ni and Co nanoparticles. Finally, the direct optical bandgaps of the nanomaterials are determined using UV-visible absorption spectroscopy. [ABSTRACT FROM AUTHOR]

The growth of mixed cobalt-iron oxides on Ru(0001) by high-temperature oxygen-assisted molecular beam epitaxy has been monitored in real time and real space by x-ray absorption photoemission microscopy. The initial composition is a mixed Fe–Co(II) oxide wetting layer, reflecting the ratio of the deposited materials. However, as subsequent growth of three dimensional spinel islands nucleating on this wetting layer takes place, the composition of the oxide in the wetting layer changes as iron is transferred into the spinel islands. The composition of the islands themselves also changes during growth. [ABSTRACT FROM AUTHOR]

Numerical simulation of a solar cell based on the heterojunction of nanocrystalline films of zinc oxide modified with cobalt oxide (Co3O4)1 –x (ZnO)x and cobalt oxide (Co3O4) formed by solid-phase pyrolysis is carried out. The effect of the electron affinity of (Co3O4)1 –x (ZnO)x films, the thickness of the Co3O4 layer and the concentration of acceptors in it on the photoelectric parameters has been studied. [ABSTRACT FROM AUTHOR]

A Co-based metal organic framework derivative is considered to be a promising electroactive material for battery and supercapacitor hybrids (BSHs) for energy conservation, owing to the large surface area, high porosity and cobalt compound composition. Cobalt oxide generates numerous redox reactions and transfers abundant electricity during the charge/discharge process due to multiple redox states. A binder-free electrode is promising to reduce fabricating costs and avoid using non-conductive binders. In this work, a new oxidized zeolitic imidazolate framework-67 (O67) is synthesized on Ni foam without a binder at different temperatures as the electroactive material for BSHs for the first time. A unique four-leaf clover (FLC) morphology is obtained for O67, and more FLC is melted at higher oxidation temperatures. The highest specific capacitance (CF) of 221.5 F g−1 at 20 mV s−1 is obtained for the O67 electrode prepared at 350 °C (O67-350), while the unoxidized electrode only presents a CF value of 91.4 F g−1. The BSH is fabricated using an O67-350 electrode and a carbon electrode. At 500 W kg−1, a maximum energy density of 23.1 W h kg−1 is obtained. Also, the CF remains at 65% of the initial value after 5000 cycles. This study initiates new design routes to develop novel zeolitic imidazolate framework-67 derivatives on nickel foam directly as binder-free electrodes. [ABSTRACT FROM AUTHOR]

Nanocrystalline mixed oxides of cobalt and manganese with spinel structure were successfully synthesized via the self-combustion method using urea as fuel and tested as catalysts for the decomposition of the green monopropellant H 2 O 2. The obtained powders were subjected to characterization by X-Ray Diffraction (XRD), Infrared Absorption Spectroscopy (FTIR), Thermogravimetric Analysis (TG), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). Additionally, the catalytic activity of the obtained samples was evaluated via measurements of the volume of gas produced and the drop test. The powder XRD analysis confirmed the crystallization of a single cubic spinel-type oxide for a higher cobalt content sample, molar Co:Mn ratio of 2:1, which presented the best catalytic performance, with faster reaction induction and a higher amount of gas produced. Additionally, the effect of calcination on the microstructural and catalytic properties was studied. The results indicate that further calcination at temperatures from 600 to 800 °C leads to a decrease in the catalytic activity, which is probably related to the loss of surface area. Only the sample calcined at 800 °C showed clear signs of particle sintering. Thus, self-combustion synthesis seems an exciting route to prepare catalysts with the required properties for application in small propulsive systems based on monopropellants, such as hydrogen peroxide. [Display omitted] • Spinel-type oxides of cobalt and manganese were successfully synthesized via the self-combustion method. • Sample with higher cobalt content showed the best catalytic properties for the decomposition of hydrogen peroxide. • Calcination of the as-prepared sample with higher cobalt content at 600–800 °C led to catalyst deactivation. • The materials prepared present the required properties for use in microthrusters for nanosatellites. [ABSTRACT FROM AUTHOR]

Cobalt oxide, a multifunctional, anti-ferromagnetic p-type semiconductor with an optical bandgap of ~2.00 eV, exhibits remarkable catalytic, chemical, optical, magnetic, and electrical properties. In our study, cobalt oxide nanoparticles (Co3O4 NPs) were prepared by the green synthesis method using dried fruit extracts of Hyphaene thebaica (doum palm) as a cost-effective reducing and stabilizing agent. Scanning electron microscopy (SEM) depicts stable hollow spherical entities which, consist of interconnected Co3O4 NPs, while energy-dispersive X-ray spectroscopy (EDS) indicates the presence of Co and O. The obtained product was identified by X-ray diffraction (XRD) that showed a sharp peak at (220), (311), (222), (400), (511) indicating the high crystallinity of the product. The Raman peaks indicate the Co3O4 spinel structure with an average shift of Δν~9 cm−1 (191~470~510~608~675 cm−1). In the Fourier transform infrared spectroscopy (FT-IR) spectrum, the major bands at 3128 cm−1, 1624 cm−1, 1399 cm−1, 667 cm−1, and 577 cm−1 can be attributed to the carbonyl functional groups, amides, and Co3O4 NPs, respectively. The photocatalytic activity of the synthesized NPs was evaluated by degrading methylene blue dye under visible light. Approximately 93% degradation was accomplished in the reaction time of 175 min at a catalyst loading of 1 g/L under neutral pH. This study has shown that Co3O4 is a promising material for photocatalytic degradation. [ABSTRACT FROM AUTHOR]

Potential low‐cost solution combustion synthesis of cobalt oxide (SCSCO: Co3O4/CoO) by using sugar as a fuel for H2 and O2 generation. Co3O4/CoO heterophase provided multiple functional sites and abundant interfaces between the components owing to synergistic effect. The sufficient adsorption sites in SCSCO6 favoured the formation of reactive intermediates which leads to extraordinary OER and HER process. The SCSCO6 exhibits η of 271 mV (102 mV dec−1) for OER and 174 mV (73 mV dec−1) for HER to achieve 10 mA cm−2 (without iR correction). TOF of SCSCO6 (OER: 0.0624 s−1/IrO2‐ 0.0185 s−1; HER: 0.0282 s−1/Pt ‐ 0.0843 s−1) was found to be higher than IrO2 and near to Pt, respectively. The SCSCO6 displays durability of 130 h with potential loss of 3.2 % (OER) and 3.0 % (HER). The disordered oxidation states and high surface area of SCSCO6 (BET ‐ 99 m2 g−1: ECSA ‐ 151.27 m2/g) facilitates the bifunctional activity. The fabricated water electrolyzer consist of SCSCO6//SCSCO6 affords 10 mA cm−2 @1.64 V and exhibits high stability (>130 h: 4.1 % potential loss). The solar‐to‐hydrogen electrolyser (SCSCO6//SCSCO6) afforded non‐stop evolution of H2 and O2 @1.63 V which can be recommended for low‐cost, large‐scale hydrogen production. [ABSTRACT FROM AUTHOR]

Thermoelectric technology has emerged as a prominent area of research in the past few decades for harnessing waste heat and improving the efficiency of next-generation renewable energy technologies. There has been rapid progress in the development of high-performance thermoelectric materials, as measured by the dimensionless figure of merit (ZT = S2 · σ · κ−1). Several heavy-metal-based thermoelectric materials with commercial-level performance (ZT = 1) have so far been proposed. However, the extensive application of these materials still faces challenges due to their low thermal/chemical stability, high toxicity, and limited abundance in the Earth's crust. In contrast, oxide-based thermoelectric materials, such as ZnO, SrTiO3, layered cobalt oxides, etc., have attracted growing interest as they can overcome the limitations of their heavy-metal-based counterparts. In this review, we summarize the recent research progress and introduce improvement strategies in oxide-based thermoelectric materials. This will provide an overview of their development history and design schemes, ultimately aiding in enhancing the overall performance of oxide-based thermoelectric materials. [ABSTRACT FROM AUTHOR]

{111}-Dominated octahedral Co 3 O 4 electrocatalyst with better adsorption performance and enhanced electron transfer exhibited good catalytic activity and high selectivity for glycerol oxidation to high-value-added chemical, i.e., dihydroxyacetone (DHA). [Display omitted] • Successful synthesis of the {111}- and {001}-dominant Co 3 O 4 electrodes. • First report of crystal engineering for the oxidation of glycerol using spinnel cobalt oxide (Co 3 O 4). • {111}-dominant octahedral Co 3 O 4 plane exhibits superior activity for glycerol oxidation. • Improved reactant adsorption, and charge transfer across distinct Co 3 O 4 facets all affect activity. To further explore the electrooxidation mechanism of biomass-based compounds, it is highly desirable to regulate the proportion of reactive facets and identify facet-governing reactivity through crystal facet engineering. In this study, octahedral and cubic cobalt spinel oxide (Co 3 O 4), each exclusively exposed by one specific type of facet, are selected as two representative microstructure models for tuning the selectivity and productivity of electrochemical glycerol oxidation reaction. The results indicate that the {111}-dominant octahedral Co 3 O 4 plane with a higher population of Co2+ sites exhibits superior electrocatalytic activity for glycerol oxidation compared with the {001}-dominant cubic Co 3 O 4 , allowing nearly 65% of glycerol to be converted into a high-value-added dihydroxyacetone (DHA) compound. The average DHA production rate over octahedral Co 3 O 4 (2.5 μmol cm−2h−1) are approximately 3.5 times greater than that over cubic Co 3 O 4 (0.7 μmol cm−2h−1). Electrochemical studies and surface atomic configuration analysis reveal that {111}-dominant octahedral Co 3 O 4 with a higher density of active cobalt ion yields unique reactant adsorption and charge transfer, leading to increased glycerol oxidation reactivity and productivity. The present study emphasizes the significance of controlling the highly active facet in developing efficient and selective electrocatalysts. [ABSTRACT FROM AUTHOR]

In the research on water splitting at neutral pH, phosphorus-containing transition metal oxyhydroxides are often employed for catalyzing the oxygen evolution reaction (OER). We investigated a cobalt–phosphate catalyst (CoCat) representing this material class. We found that CoCat films prepared with potassium phosphate release phosphorus in phosphate-free electrolytes within hours, contrasting orders of magnitude's faster K+ release. For P speciation and binding mode characterization, we performed technically challenging X-ray absorption spectroscopy experiments at the P K-edge and analyzed the resulting XANES and EXAFS spectra. The CoCat-internal phosphorus is present in the form of phosphate ions. Most phosphate species are likely linked to cobalt ions in Co–O–PO3 motifs, where the connecting oxygen could be a terminal or bridging ligand in Co-oxide fragments (P–Co distance, ~3.1 Å), with additional ionic bonds to K+ ions (P–K distance, ~3.3 Å). The phosphate coordination bond is stronger than the ionic K+-binding, explaining the strongly diverging ion release rates of phosphate and K+. Our results support a structural role of phosphate in the CoCat, with these ions binding at the margins of Co-oxide fragments, thereby limiting the long-range material ordering. The relations of catalyst-internal phosphate ions to cobalt's redox-state changes, proton transfer, and catalytic activity are discussed. [ABSTRACT FROM AUTHOR]

Co-based catalysts were synthesized and studied as novel oxidation catalysts, exploring and optimizing the effect of synthesis method on the redox behavior, the oxygen storage ability and thus the catalytic performance of the derived Co3O4 materials in the complete CH4 and/or CO oxidation reactions. Thus, a series of Co-based catalysts were synthesized applying either the precipitation and/or the hydrothermal method, using different precipitating agents (Na2CO3, NH3, urea or NaOH), Co precursor salt (nitrate or acetate) and finally varying the Co/Na ratio. In addition, the reaction time (6 or 24 h aging) was also investigated for the hydrothermally prepared Co3O4. The best catalysts for the CH4 oxidation are the precipitated Co3O4, using cobalt acetate as precursor salt and NaOH as precipitating agent, presenting the highest surface areas and the lowest Co3O4 particle sizes. On the other side, hydrothermally prepared cobalt oxides reveal higher performance for CO oxidation, with Co3O4 prepared with cobalt acetate, NaOH and low aging time shown as the optimum materials. The best catalysts were further promoted with incorporation of Pd (0.5wt.%) and explored for both reactions. The addition of Pd enhanced the activity of Co3O4 for CH4 oxidation, while Pd did not improve any further the catalyst performance for CO oxidation, presenting thus the same activity with pure cobalt oxides. [ABSTRACT FROM AUTHOR]

Simple Summary: This study was carried out to ascertain the toxicity of synthetic cobalt iron oxide (CoFe2O4) nanoparticles (CIONPs) in rabbits. Sixteen rabbits in total were purchased from the neighborhood market and divided into two groups (A and B), each of which contained eight rabbits. The CIONPs were synthesized by the co-precipitation method and were administrated intravenously into the rabbits through the ear vein. Blood was collected at days 5 and 10 post-exposure for hematological and serum biochemistry analyses. Different histological ailments were also observed in the visceral organs of treated rabbits. Cobalt iron oxide (CoFe2O4) nanoparticles appeared to induce toxicity in rabbits. The market for nanoparticles has grown significantly over the past few decades due to a number of unique qualities, including antibacterial capabilities. It is still unclear how nanoparticle toxicity works. In order to ascertain the toxicity of synthetic cobalt iron oxide (CoFe2O4) nanoparticles (CIONPs) in rabbits, this study was carried out. Sixteen rabbits in total were purchased from the neighborhood market and divided into two groups (A and B), each of which contained eight rabbits. The CIONPs were synthesized by the co-precipitation method. Crystallinity and phase identification were confirmed by X-ray diffraction (XRD). The average size of the nanoparticles (13.2 nm) was calculated by Scherrer formula (Dhkl = 0.9 λ/β cos θ) and confirmed by TEM images. The saturation magnetization, 50.1 emug−1, was measured by vibrating sample magnetometer (VSM). CIONPs were investigated as contrast agents (CA) for magnetic resonance images (MRI). The relaxivity (r = 1/T) of the MRI was also investigated at a field strength of 0.35 T (Tesla), and the ratio r2/r1 for the CIONPs contrast agent was 6.63. The CIONPs were administrated intravenously into the rabbits through the ear vein. Blood was collected at days 5 and 10 post-exposure for hematological and serum biochemistry analyses. The intensities of the signal experienced by CA with CIONPs were 1427 for the liver and 1702 for the spleen. The treated group showed significantly lower hematological parameters, but significantly higher total white blood cell counts and neutrophils. The results of the serum biochemistry analyses showed significantly higher and lower quantities of different serum biochemical parameters in the treated rabbits at day 10 of the trial. At the microscopic level, different histological ailments were observed in the visceral organs of treated rabbits, including the liver, kidneys, spleen, heart, and brain. In conclusion, the results revealed that cobalt iron oxide (CoFe2O4) nanoparticles induced toxicity via alterations in multiple tissues of rabbits. [ABSTRACT FROM AUTHOR]

High‐resolution computed tomography (micro‐CT) was used in this paper to visualize the inner structure of lithium nickel cobalt aluminum oxide 18 650 form‐factor batteries non‐destructively after and during a heat endurance test. Open circuit relaxation and electrochemical impedance spectroscopy were also conducted. We tested the different heat‐aged cells with micro‐CT and charge‐discharge and electrochemical impedance spectroscopy measurements to find the observable physical changes in the cell and connect them to the loss of performance. We found that the drastic changes in the structure of the cell at higher temperatures are well traceable. At 150 °C layer delamination and performance loss were observed, battery failure occurred with the further increase of the temperature, while at the same time, precipitation appeared and the positive temperature coefficient device fractured. Without opening the cell only tomographic methods can provide insight into the inner structure of the cell. We were able to measure the changes in the distances of the layers of the battery and decent shrinkage was observed, which can be linked to the loss of capacity and increased resistance. [ABSTRACT FROM AUTHOR]

Highly dispersed Pt-based catalysts were prepared by Strong Electrostatic Adsorption (SEA) for the PROX reaction. The effect of the catalyst synthesis pH was investigated to control the metal-support interactions for the system: Pt supported onto cobalt oxide, previously supported on TiO 2. The Pt/CoO x /TiO 2 catalysts were prepared in a pH range of 3.0–9.0, obtaining Pt dispersion values above 90% with Pt crystallite sizes of 1–2 nm. The effect of the synthesis pH was correlated with the concentration of (Pt-CoO x) i interfacial sites, and this, in turn, with the catalytic activity. The concentration of (Pt-CoO x) i interfacial sites was higher for the most active catalyst, which was prepared at a condition that ensures a higher selective-SEA of Pt over the co-support (pH = 6.0). This study shows that the synthesis pH can determine the concentration and type of active sites and paves the way to use SEA to control the activity of dual-supported catalysts. [Display omitted] • Highly dispersed Pt/CoO x /TiO 2 catalysts were prepared by SEA at pH values of 3–8. • The amount of (Pt-CoO x) i interfacial sites was tuned by varying the synthesis pH. • The activity was correlated with the concentration of (Pt-CoO x) i interfacial sites. • The catalysts prepared at selective-SEA conditions showed an enhanced activity. [ABSTRACT FROM AUTHOR]

Advancements in the metal oxides‐based electrode material for the fabrication of supercapacitors have been an important focus of research in recent times. The electrochemical properties of electrode materials play a vital role in the excellent performance of the supercapacitor. In this regard, the doping of Co3O4 nanoparticles (NPs) with PdO/Pd using the ecofriendly extracted foliar reducing and stabilizing agent from Euphorbia cognata is analyzed. The as‐synthesized Co3O4:PdO/Pd nanocomposite exhibits a multifaceted phase composition, characterized by a particle size of 22 nm and a bandgap energy of 2.28 eV. Remarkably, an obvious reduction in bandgap energy is observed, indicative of the heightened electrochemical performance of the Co3O4:PdO/Pd nanocomposite. Galvanostatic charge–discharge techniques elucidate impressive electrochemical properties, including a 202 F g−1 specific capacitance and an exceptionally small resistance value of 1.04 Ω. These findings not only infer efficient charge particle diffusion, but also signify an enhanced charge storage capacity. Thus, the outcomes of this study state the potential of functionalized foliar Co3O4:PdO/Pd nanocomposites as a promising choice for advanced electrode materials in supercapacitor applications. Importantly, this study highlights the significance of utilizing cost‐effective and sustainable materials in the development of pioneering energy storage materials, contributing the advancement of materials field. [ABSTRACT FROM AUTHOR]

Electrochemical conversion of nitrate to ammonia is an appealing way for small‐scale and decentralized ammonia synthesis and waste nitrate treatment. Currently, strategies to enhance the reaction performance through elaborate catalyst design have been well developed, but it is still of challenge to realize the promotion of reactivity and selectivity at the same time. Instead, a facile method of catalyst modification with ionic liquid to modulate the electrode surface microenvironment that mimic the role of the natural MoFe protein environment is found effective for the simultaneous improvement of NH3 yield rate and Faradaic efficiency (FE) at a low NaNO3 concentration of 500 ppm. Protic ionic liquid (PIL) N‐butylimidazolium bis(trifluoromethylsulfonyl)imide ([Bim]NTf2) modified Co3O4−x is fabricated and affords the NH3 yield rate and FE of 30.23±4.97 mg h−1 mgcat.−1 and 84.74±3.43 % at −1.71 and −1.41 V vs. Ag/AgCl, respectively, outperforming the pristine Co3O4−x. Mechanistic and theoretical studies reveal that the PIL modification facilitates the adsorption and activation of NO3− as well as the NO3−‐to‐NH3 conversion and inhibits hydrogen evolution reaction competition via enhancing the Lewis acidity of the Co center, shuttling protons, and constructing a hydrogen bonded and hydrophobic electrode surface microenvironment. [ABSTRACT FROM AUTHOR]

The combination of an intense absorption of visible light and p-type semiconducting nature makes spinel cobalt oxide (Co 3 O 4) a very attractive material for various optoelectronic applications. However, the traditional methods for its synthesis have been either time- and energy-consuming or relying on toxic chemicals. To solve this issue, a simple, facile, and eco-friendly method of synthesis was successfully developed to obtain spinel Co 3 O 4 nanoparticles. The novel method for obtaining pure and monophasic Co 3 O 4 reported here is based on the thermal decomposition of hexaaquacobalt(II) D-camphor10-sulfonate at 900 °C. This fast solid-state synthesis route overcomes the disadvantages of many combustion methods, most critically by avoiding the use of toxic organic solvents. The synthesized material was subjected to a detailed characterization to assess its potential for use as a nanocatalyst. The band gap measurements indicated the presence of two band gaps, one at 2.10 eV and another at 1.22 eV, confirming the purity and semiconducting properties of the sample. The electrochemical studies demonstrated a significant enhancement in the electron transfer kinetics with the addition of the synthesized Co 3 O 4 to the carbon-paste electrode, leading to an enhanced electrocatalytic performance. These prominent functional properties, suitable for a wide range of technological applications, pave way for the implementation of the reported method for the synthesis of Co 3 O 4 on a larger industrial scale. [Display omitted] [ABSTRACT FROM AUTHOR]

High‐valent metal‐oxo (HVMO) species are powerful non‐radical reactive species that enhance advanced oxidation processes (AOPs) due to their long half‐lives and high selectivity towards recalcitrant water pollutants with electron‐donating groups. However, high‐valent cobalt‐oxo (CoIV=O) generation is challenging in peroxymonosulfate (PMS)‐based AOPs because the high 3d‐orbital occupancy of cobalt would disfavor its binding with a terminal oxygen ligand. Herein, we propose a strategy to construct isolated Co sites with unique N1O2 coordination on the Mn3O4 surface. The asymmetric N1O2 configuration is able to accept electrons from the Co 3d‐orbital, resulting in significant electronic delocalization at Co sites for promoted PMS adsorption, dissociation and subsequent generation of CoIV=O species. CoN1O2/Mn3O4 exhibits high intrinsic activity in PMS activation and sulfamethoxazole (SMX) degradation, highly outperforming its counterpart with a CoO3 configuration, carbon‐based single‐atom catalysts with CoN4 configuration, and commercial cobalt oxides. CoIV=O species effectively oxidize the target contaminants via oxygen atom transfer to produce low‐toxicity intermediates. These findings could advance the mechanistic understanding of PMS activation at the molecular level and guide the rational design of efficient environmental catalysts. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous Al‐ion batteries (AIBs) are promising low‐cost, safe, and high energy density systems for large‐scale energy storage. However, the strong electrostatic interaction between the Al3+ and the host material, usually leads to sluggish Al3+ diffusion kinetics and severe structure collapse of the cathode material. Consequently, aqueous AIBs currently suffer from low energy density as well as inferior rate capability and cycling stability. Here, defective cobalt manganese oxide nanosheets are reported as cathode material for aqueous AIBs to improve both reaction kinetics and stability, delivering a record high energy density of 685 Wh kg−1 (based on the masses of the cathode and anode) and a reversible capacity of 585 mAh g−1 at 100 mA g−1 with a retention of 78% after 300 cycles. The impressive energy density and cycling stability are due to a synergistic effect between the substituted cobalt atoms and the manganese vacancies, which improve the structural stability and promote both electron conductivity and ion diffusion. When applied in aqueous Zn‐ion batteries, a high specific energy of 390 Wh kg−1 at 100 mA g−1 is realized while retaining 84% initial capacity over 1000 cycles. The study offers a new pathway to building next‐generation high‐energy aqueous rechargeable metal batteries. [ABSTRACT FROM AUTHOR]

The design of hybrid electrocatalysts with abundant active sites and long term stability is crucial for efficient oxygen evolution reaction (OER) application. Cobalt oxide is considered as one of the most promising electrocatalysts to replace noble metal due to its low cost, availability, and electrocatalytic activity towards the oxygen evolution reaction in alkaline media. However, nano-scale cobalt oxide suffers from severe surface self-agglomeration during the OER process, so that leading to poor activity and durability. Herein, ultra-small cobalt oxide nanoparticles are anchored on the surface of nitrogen doped porous 3D graphitic carbon nano-spheres (N-ACS@Co 3 O 4) to increase the amount of exposed active site and avoid the self-agglomeration. The obtained electrocatalyst (N-ACS@Co 3 O 4) is enriched with abundant oxygen vacancies and exhibits a superior OER activity (Overpotential of 237 mV at 10 mA.cm−2) and exceptional stability for at least 30 h in alkaline electrolyte (1 M KOH). The DFT calculations demonstrate that the strong adsorption of Co 3 O 4 on N-doped graphene can prevent its agglomeration, and therefore improves the stability of Co 3 O 4 nanoparticles during OER process in line with the experimental results. • Cobalt oxide nanoparticles are synthesized on the surface of nitrogen doped carbon. • The hybrid composite enhances the conductivity, charge transfer and generate additional defect active sites. • The N-ACS@Co 3 O 4 exhibits a superior OER activity and exceptional long-term durability. • DFT calculations demonstrate a strong adsorption of Co 3 O 4 on N-doped graphene. • The strong adsorption of Co 3 O 4 prevents its agglomeration, and improves the stability. [ABSTRACT FROM AUTHOR]

Corrosion behavior of electrolytic binary and ternary alloys in the 1 M KOH solution deposited from citrate-pyrophosphate electrolytes is studied. Based on the performed impedance measurements, the formation of a dense oxide layer which blocks the access of the electrolyte to the metal through cracks and pores is shown. Equivalent schemes have been selected and substantiated, and the parameters of the corrosion process have been calculated for 9 days of the samples exposure to the corrosive solution. Using chemical mapping it is shown that the corrosion product is predominantly cobalt oxide. A ternary alloy is characterized by a higher initial corrosion resistance of 6 kΩ×cm–2 and a significant polarization resistance after slowing down and stabilization of the corrosion process – 37 kΩ×cm–2. [ABSTRACT FROM AUTHOR]

This study is focused on the effects of annealing temperature and pH on the crystallinity of cobalt oxide (Co3O4) nanoparticles (NPs) synthesized via sol-gel method. X-ray diffraction (XRD) analysis was carried out to investigate the crystalline structure and size of the NPs. The results indicated that increasing the pH from 10 to 14 during NPs synthesis led to an increase in crystallinity, as evidenced by the appearance of Bragg reflections upon calcination. On the other hand, increasing the calcination temperature from 120°C to 800°C also increased the crystallinity of Co3O4 NPs, as seen by the appearance of additional Bragg reflections and an increase in crystallite size. These findings demonstrate the significance of pH and calcination temperature in controlling the crystallinity and properties of Co3O4 NPs. [ABSTRACT FROM AUTHOR]

The reduction pathway of Co catalysts supported on untreated SiO2 along with two pretreated SiO2 support materials was investigated. In situ XRD studies clearly showed the likely reduction pathways of the cobalt oxides on the untreated SiO2, ethylene glycol pretreated SiO2, and annealing pretreated SiO2 supports. Ethylene glycol pretreated SiO2-supported Co (Co/E–SiO2) catalyst showed smaller metal crystallites, highly dispersed Co and high Co(hcp)/Co(fcc) ratio because of the high percentage of non-H-bonded silanols; however, the high percentage of the non-H-bonded silanols created a strong Co-SiO2 interaction which caused a low degree of reduction of CoO resulting in lower FT activity. In contrast, the annealing pretreated SiO2-supported Co (Co/A–SiO2) catalyst did not significantly increase the percentage of non-H-bonded silanols and Co(hcp)/Co(fcc) ratio when compared with Co/E–SiO2, but it exhibited a better catalytic activity during FTS. [ABSTRACT FROM AUTHOR]

In this study, cobalt ferrite and magnesium oxide nanoparticles were synthesized by co-precipitation and sol–gel methods, respectively. Magnesium oxide doped cobalt ferrite nanocomposites were prepared by mixing powder forms of cobalt ferrite nanoparticles with 10% and 25% in weight MgO powders. The SEM and XRD analyses revealed that pure spinel ferrite structure and single phase magnesium oxide nanoparticles without impurities are obtained. The structural analyses also approved the formation of both phases coexisting in the nanocomposite with homogenous distribution in nanometer particle sizes. In vitro cytotoxic effects of the samples with several concentrations on L929 mouse fibroblast cells were investigated. It is seen that cobalt ferrite nanoparticles increased cell viability in all concentrations and the cell viability of nanocomposites also has been observed as over 95%. Additionally, the energy storage ability of the nanocomposites is performed by frequency-dependent admittance measurements in 5 Hz–13 MHz frequency ranges. It is seen that the addition of magnesium oxide content reduced the complex dielectric constant and dielectric loss of the cobalt ferrite-based nanocomposites effectively. The results showed that magnesium oxide-doped cobalt ferrite nanocomposites sustain nontoxic behavior for biomedical applications in addition to their adjustable dielectric parameters. [ABSTRACT FROM AUTHOR]

The cobalt catalysts supported on perovskite-type XCeO3 (X: Mg, Ca, Sr, Ba) oxide were prepared for the decomposition of ammonia. The influence of different alkaline earth metals in support composition on the catalytic activity of Co/XCeO3 catalysts has been studied. A nominal 5 wt% Co loading was maintained over these perovskite supports. The catalytic ammonia decomposition performance was studied in the temperature range 300–600 °C. The catalyst 5Co–BaCeO (5 wt% Co impregnated on BaCeO3 support) showed the highest activity among the all other catalysts and the sequential order of exhibited NH3 conversion was as follows: 5Co–MgCeO < 5Co–CaCeO ≤ 5Co–SrCeO < 5Co–BaCeO. The synthesized catalysts were characterized by BET, XRD, TPR, CO2-TPD and SEM techniques. The results showed that the interaction between BaCeO3 and Co is beneficial to electron conductivity that promotes the catalytic activity of 5Co–BaCeO. The basicity of 5Co–BaCeO catalysts facilitates the re-combinative desorption of surface N atoms which help in enriching the ammonia decomposition. [ABSTRACT FROM AUTHOR]

Complex metal oxide nanomaterials, like lithiated cobalt oxide (LCO) nanosheets, are among the most widespread classes of nanomaterials on the market. Their ubiquitous application in battery storage technology drives their production to rates of environmental significance without sufficient infrastructure for proper disposal/recycling, thus posing a risk to ecosystem health and sustainability. The present study assesses the general toxicological impacts of LCO when exposed to Raphidocelis subcapitata; physiological endpoints relating to growth and energy production are considered. Algal growth inhibition was significantly increased at concentrations as low as 0.1 µg ml−1, while exhibiting a median effect concentration of 0.057 µg ml−1. The average biovolume of cells was significantly enlarged at 0.01 µg ml−1, thus indicating increased instances of cell cycle arrest in LCO‐treated cells. In addition, LCO‐treated cells produced significantly less carbon biomass while significantly overproducing neutral lipid content starting at 0.1 µg ml−1, thus indicating interference with CO2 assimilation chemistry and/or carbon partitioning. However, the relative abundance of chlorophyll was significantly increased, likely to maximize light harvesting and compensate for photosynthetic interference. Cells that were treated with dissolved Li+/Co2+ ions did not significantly impact any of the endpoints tested, suggesting that LCO phytotoxicity is mainly induced through nano‐specific mechanisms rather than ion‐specific ones. These results indicate that this type of nanomaterial can significantly impact the way this alga proliferates, as well as the way it produces and stores its energy, even at lower, sublethal, concentrations. Furthermore, impairments to crucial cellular pathways, like carbon assimilation, could potentially cause implications at the ecosystem level. Thus, in future work, it will be important to characterize the molecular mechanisms of LCO at the nano–bio interface. Environ Toxicol Chem 2023;42:1451–1462. © 2023 SETAC [ABSTRACT FROM AUTHOR]

Only rarely have polyoxometalates been found to form core–shell nanoclusters. Here, we succeeded in isolating a series of rare giant and all‐inorganic core–shell cobalt polyoxoniobates (Co−PONbs) with diverse shapes, nuclearities and original topologies, including 50‐nuclearity {Co12Nb38O132}, 54‐nuclearity {Co20Nb34O128}, 62‐nuclearity {Co26Nb36O140} and 87‐nuclearity {Co33Nb54O188}. They are the largest Co−PONbs and also the polyoxometalates containing the greatest number of Co ions and the largest cobalt clusters known thus far. These molecular Co−PONbs have intriguing and atomically precise core–shell architectures comprising unique cobalt oxide cores and niobate oxide shells. In particular, the encapsulated cobalt oxide cores with different nuclearities have identical compositions, structures and mixed‐valence Co3+/Co2+ states as the different sized Co−O moieties of the bulk cubic‐spinel Co3O4, suggesting that they can serve as various molecular models of the cubic‐spinel Co3O4. The successful construction of the series of the Co−PONbs reveals a feasible and versatile synthetic method for making rare core–shell heterometallic PONbs. Further, these new‐type core–shell bimetal species are promising cluster molecular catalysts for visible‐light‐driven CO2 reduction. [ABSTRACT FROM AUTHOR]

High energy density and intrinsic safety are the central pursuits in developing rechargeable Zinc‐ion batteries (ZIBs). The capacity and stability of nickel cobalt oxide (NCO) cathode are unsatisfactory because of its semiconductor character. Herein, we propose a built‐in electric field (BEF) approach by synergizing cationic vacancies and ferroelectric spontaneous polarization on cathode side to facilitate electron adsorption and suppress zinc dendrite growth on the anode side. Concretely, NCO with cationic vacancies was constructed to expand lattice spacing for enhanced zinc‐ion storage. Heterojunction with BEF leads to the Heterojunction//Zn cell exhibiting a capacity of 170.3 mAh g−1 at 400 mA g−1 and delivering a competitive capacity retention of 83.3 % over 3000 cycles at 2 A g−1. We conclude the role of spontaneous polarization in suppressing zinc dendrite growth dynamics, which is conducive to developing high‐capacity and high‐safety batteries via tailoring defective materials with ferroelectric polarization on the cathode. [ABSTRACT FROM AUTHOR]

Recently, cobalt oxides/hydroxides have attracted increasing attention in the electrocatalytic oxidation reaction of 5-hydroxymethylfurfural (HMFOR) under ambient conditions for 2,5-furandicarboxylic acid (FDCA) production, but understanding of the interplay of defective sites (i.e., oxygen vacancies and porosity) remains lacking. Herein, a series of defective cobalt oxide hydrate (CoOxHy) nanosheets were fabricated via room-temperature reductive treatments with methylamine (MA) and/or NaBH4 (BH). These defective CoOxHy nanosheets possessed abundant oxygen vacancies in relation to high Co2+/Co3+ ratios and high porosity, with a largely maintained ultrathin lamellar framework, and thus exhibited markedly improved catalytic activity and selectivity for HMFOR. DFT calculations also verified the beneficial role of oxygen vacancies towards HMF adsorption and activation, preferentially via the aldehyde group of HMF. In the optimal CoOxHy-MA, 98% FDCA yield and a faradaic efficiency of 83% were achieved within 200 min at a constant potential of 1.52 V vs. RHE. The mesoporosity mainly induced by MA improved the mass transportation of reactants and products, leading to a higher rate of HMFOR. Meanwhile, with the additional in-sheet micropores mainly induced by BH, the selectivity towards the oxidation intermediate 5-formyl-2-furancarboxylic acid (FFCA) significantly increased, probably due to the accelerated penetration of FFCA instead of further oxidation to FDCA. This work highlights the simultaneous regulation of the oxygen vacancies and porosity of metal oxide/hydroxide catalysts by facile reductive treatments for efficient electrochemical biomass conversion. [ABSTRACT FROM AUTHOR]

In this work, we present the structural, optical and photocatalytic properties of CdS semiconducting nanostructures, doped with palladium‐ and cobalt‐based species. XRD analysis, corroborated by Raman and XPS, demonstrated the growth of CdS crystallites in the hexagonal structure, whereas solvothermal conversion of neat precursor metal salts resulted in the formation of metallic Pd and cobalt oxide, respectively. Scanning electron microscopy imaging certified the dendritic structure of hybrids, especially in the case where CdS was grown in the presence of either palladium‐ or cobalt‐based nanoparticles. XPS surface analysis revealed that a major fraction of metallic Pd nanoparticles was converted to PdO during the in situ growth of CdS nanoparticles. The oxidation of Pd nanoparticles could be ascribed to chemisorption of oxygen phases onto the metal surface. The presence of cocatalyst nanoparticles resulted in an appreciable shift of the absorption edge of the ternary hybrids by about 50 nm. The optimized hybrid was found to photodegrade Orange G dye almost quantitatively within 2 h, by simulated solar light irradiation. Scavenging experiments revealed that hydroxy radicals were the main transient intermediate, leading to the oxidative degradation of the dye. [ABSTRACT FROM AUTHOR]

Thermomicroscopy, or hot-stage microscopy, is primarily used in the analysis of organic materials such as pharmaceuticals and polymers. However, its potential application to the study of inorganic systems remains largely unexplored. A thermomicroscope was developed utilising red, green, blue (RGB) colour profiles and individual micrographs taken at fixed temperatures to follow temperature programmed reduction processes under a hydrogen atmosphere. The instrument was used for the study of the reduction in the oxides of silver, copper, lead, and cobalt. To the best of the authors' knowledge, this is the first time that temperature programmed reduction processes have been followed using thermomicroscopy and our results suggest the presence of transient intermediate phases within the lead oxide and cobalt oxide systems. [ABSTRACT FROM AUTHOR]

[Display omitted] Heteroatom doping is one of the feasible strategies to improve electrode efficiency. Meanwhile, graphene helps to optimize structure and improve conductivity of the electrode. Here, we synthesized a composite of boron-doped cobalt oxide nanorods coupled with reduced graphene oxide by a one-step hydrothermal method and investigated its electrochemical performance for sodium ion storage. Because of the activated boron and conductive graphene, the assembled sodium-ion battery shows excellent cycling stability with a high initial reversible capacity of 424.8 mAh g−1, which is maintained as high as 444.2 mAh g−1 after 50 cycles at a current density of 100 mA g−1. The electrodes also exhibit excellent rate performance with 270.5 mAh g−1 at 2000 mA g−1, and retain 96% of the reversible capacity upon recovery from 100 mA g−1. This study shows that boron doping can increase the capacity of cobalt oxides and graphene can stabilize structure and improve conductivity of the active electrode material, which are essential for achieving satisfactory electrochemical performance. Therefore, the doping of boron and introduction of graphene may be one of the promising means to optimize the electrochemical performance of anode materials. [ABSTRACT FROM AUTHOR]

To improve the catalytic activity of Co3O4 for CO oxidation, we synthesized a series of Co3O4 catalysts (x%La-Co3O4) with different La doping amounts using the deposition–precipitation method and investigated their catalytic activities and water resistance. The results indicated that the trace doping of La (i.e., 1.0–3.0 atom%) significantly improved the catalytic activity of Co3O4 for CO oxidation. The main reason was that the doped La increased the content of Co3+ in Co3O4, which was the main active Co species for CO oxidation. In addition, doping with La improved the water resistance and catalytic stability of Co3O4 under wet conditions. Pure Co3O4 was dramatically deactivated within a short period (the CO conversion decreased by 80% in 1 h), while 2%La-Co3O4 maintained a CO conversion of over 75% within 15 h. The improved water resistance of 2%La-Co3O4 was mainly due to the reduced hydroxyl content on the Co3O4 surface, which increased the surface hydrophobicity of Co3O4. This work is expected to provide a strategy for the preparation of water-resistant and highly active Co3O4 catalysts for CO oxidation. [ABSTRACT FROM AUTHOR]

A low-grade copper-cobalt oxide ore containing 0. 98% Cu and 0. 07% Co from Congo(DRC), Africa was leached via sodium sulfite enhanced reduction-leaching technology. The effect of process parameters on leaching under conventional sulfuric acid leaching system was emphatically studied. The experimental results show that under the conditions of initial sulfuric acid concentration of 2 mol/L, liquid-solid ratio of 2 : 1, - 0. 074 mm proportion of 68. 27%,adding 4% reducing agent, total leaching time of 6 h and leaching temperature of 80 °C, the optimal leaching rate of Cu and Co can reach 96. 50% and 85. 21%, respectively. Per ton raw ore acid consumption of 305. 09 kg. The residual cobalt in leaching residue mainly occurs in sulphur-copper-cobalt ore and limonite, while the cobalts, in hydrocobalt ore and copper-cobalt hard manganese ore are basically leached. [ABSTRACT FROM AUTHOR]

The catalytic conversion of CO2 into valuable commodities has the potential to balance ongoing energy and environmental issues. To this end, the reverse water–gas shift (RWGS) reaction is a key process that converts CO2 into CO for various industrial processes. However, the competitive CO2 methanation reaction severely limits the CO production yield; therefore, a highly CO-selective catalyst is needed. To address this issue, we have developed a bimetallic nanocatalyst comprising Pd nanoparticles on the cobalt oxide support (denoted as CoPd) via a wet chemical reduction method. Furthermore, the as-prepared CoPd nanocatalyst was exposed to sub-millisecond laser irradiation with per-pulse energies of 1 mJ (denoted as CoPd-1) and 10 mJ (denoted as CoPd-10) for a fixed duration of 10 s to optimize the catalytic activity and selectivity. For the optimum case, the CoPd-10 nanocatalyst exhibited the highest CO production yield of ∼1667 μmol g−1catalyst, with a CO selectivity of ∼88% at a temperature of 573 K, which is a 41% improvement over pristine CoPd (~976 μmol g−1catalyst). The in-depth analysis of structural characterizations along with gas chromatography (GC) and electrochemical analysis suggested that such a high catalytic activity and selectivity of the CoPd-10 nanocatalyst originated from the sub-millisecond laser-irradiation-assisted facile surface restructure of cobalt oxide supported Pd nanoparticles, where atomic CoOx species were observed in the defect sites of the Pd nanoparticles. Such an atomic manipulation led to the formation of heteroatomic reaction sites, where atomic CoOx species and adjacent Pd domains, respectively, promoted the CO2 activation and H2 splitting steps. In addition, the cobalt oxide support helped to donate electrons to Pd, thereby enhancing its ability of H2 splitting. These results provide a strong foundation to use sub-millisecond laser irradiation for catalytic applications. [ABSTRACT FROM AUTHOR]

This article presents studies on the recovery of cobalt from a spent cobalt oxide catalyst, left after the preparation of industrial catalysts. Apart from cobalt, the tested material contained iron, copper, zinc, and nickel. Leaching was proposed as a simple and feasible operation to treat the spent cobalt oxide. The 0.1–8.0 M H2SO4 solutions were applied as leaching agents at an ambient temperature and at 70 °C. An 8.0 M H2SO4 solution at 70 °C leached two-fold more Co(II) than a 0.1 M H2SO4 solution at the same temperature. Similar to Co(II), regardless of the leaching temperature, the Fe ion was leached more efficiently with 4.0 or 8.0 M H2SO4 than with a 0.1 M acid. It should be emphasized that the Co(II) content in the solution after leaching was predominant at >90% (~4800 mg/dm3), compared to other metal ions. The ANOVA analysis indicated that both the sulfuric(VI) acid concentration and temperature had a significant effect on the leaching efficiency. An increase in acid concentration from 0.1 to 8 M and the temperature of leaching (from ambient to 70 °C) had a positive effect on the Co leaching efficiency (an increase from ~20 to almost 50%). The proposed hydrometallurgical treatment of the spent cobalt oxide catalyst is a response to the waste-to-resource (WTR) approach. [ABSTRACT FROM AUTHOR]

In the present work barium sodium borate glass samples with the nominal compositions 55B2O3 +(25-x)BaF2 + 20Na2O + xCo3O4 where x = 0, 0.5, 1, 0.75, 1.5, and 2 mol % were prepared by the conventional melt-quenching technique. The structural, thermal, optical and magnetic characteristics of Co doped barium sodium borate glasses have been considered. The amorphous nature of the prepared glass samples were confirmed by X-ray diffraction (XRD) spectra. Fourier-Transform Infrared spectroscopy (FTIR) has been recorded in the range of 4000–400 cm− 1 to estimate the vibrational and dynamics of cobalt doped barium sodium borate glass samples. Differential thermal analysis (DTA) was used to perform the glass transition investigations. The values of Tg and TC significantly improved with increasing cobalt oxide concentration, according to (DTA) thermal analysis.UV–Vis spectra of the prepared glass samples were detected over the range of 200–2500 nm. The optical absorption spectra were used to estimate optical energy band gaps of the prepared glasses. It was observed that the direct and indirect optical band gaps were decreased with increasing Co3O4 content. The magnetization hysteresis loops for prepared glass system has been estimated. The coercivity of the glass samples for all Co3O4 content is small and the magnetization saturation increased from 0.2 to 0.58 esu/g as the concentration of Co3O4 varied from 0.0 to 2.0 mol%. [ABSTRACT FROM AUTHOR]

Owing to the paradigm shift of the automobile industry toward the electrification of vehicles, the aftermath of batteries that power these devices at the end of their lives has to be addressed strenuously. Since upcycling strategies are hardly in the limelight, this paper focuses on giving a second life to LiCoO2 cathode as a dual‐ion battery (DIB) anode. Among many possible recovery approaches explored for cobalt, a microwave‐assisted green leaching method comprising mild leaching agents is chosen for this work. Cobalt is recovered as cobalt oxalate and converted to cobalt/cobalt oxide nanospheres embedded in a porous graphitic carbon matrix (Co3O4/Co@C). Due to the high working voltage, excellent safety, and environmental friendliness, DIBs are being considered as a replacement for lithium‐ion batteries in specific sectors. In an unconventional approach, the derived Co3O4/Co@C is effectively employed as an anode material for dual‐ion batteries. The half‐cell demonstrates a high discharge capacity of 550 mAh g−1 at 0.1 A g−1. A full‐cell DIB fabricated using Co3O4/Co@C, derived from upcycled LiCoO2 as an anode and graphite as a cathode, shows an appreciable capacity and remarkable cycling stability. This sustainable approach for upcycling exhausted LIBs can pave the way to improve the circular economy of batteries. [ABSTRACT FROM AUTHOR]

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