Addition Of Co3O4 Research Articles

Key Role of Interfacial Cobalt Segregation in Stable Low-Resistance Composite Oxygen-Reducing Electrodes.

The development of efficient and stable oxygen-reducing electrodes is challenging but vital for the production of efficient electrochemical cells. Composite electrodes composed of mixed ionic-electronic conducting La1-xSrxCo1-yFeyO3-δ and ionic conducting doped CeO2 are considered promising components for solid oxide fuel cells. However, no consensus has been reached regarding the reasons of the good electrode performance, and inconsistent performance has been reported among various research groups. To mitigate the difficulties related to analyzing composite electrodes, this study applied three-terminal cathodic polarization to dense and nanoscale La0.6Sr0.4CoO3-δ-Ce0.8Sm0.2O1.9 (LSC-SDC) model electrodes. The critical factors determining the performance of the composite electrodes are the segregation of catalytic cobalt oxides to the electrolyte interfaces and the oxide-ion conducting paths provided by SDC. The addition of Co3O4 to the LSC-SDC electrode resulted in reduced LSC decomposition; thus, the interfacial and electrode resistances were low and stable. In the Co3O4-added LSC-SDC electrode under cathodic polarization, Co3O4 turned wurtzite-type CoO, which suggested that the Co3O4 addition suppressed the decomposition of LSC and, thus, the cathodic bias was maintained from the electrode surface to electrode-electrolyte interface. This study shows that cobalt oxide segregation behavior must be considered when discussing the performance of composite electrodes. Furthermore, by controlling the segregation process, microstructure, and phase evolution, stable low-resistance composite oxygen-reducing electrodes can be fabricated.

Production of renewable fuel from CO2 by Co3O4/Cr doped MgAl–LDH p-n heterojunction catalyst

Converting CO2 into renewable fuel via photocatalysis is of significance to solving the energy crisis and climate change. However, the limited electron transfer in single catalysts always limits the reduction reaction. In this work, a p-n heterojunction was constructed between Cr doped MgAl–LDH (abbreviated as LDH) and Co3O4 for visible-light-driven fuel production. Since LDH and Co3O4 both have the sufficient potentials to drive CO2 photoreduction, the constructed type-II heterojunction is more favorable for electron utilization efficiency. The optimal Co3O4/LDH heterojunction exhibited the highest CO evolution rate of 7.42 μmol•g−1•h−1 and a CO selectivity of 90.5% with TEOA as sacrificial agent. The further characterizations highlight that the addition of Co3O4 greatly improves the light absorption and the heterojunction effectively promotes the reverse migration of electrons and holes. This work investigates and verifies the designed type-II heterojunction based on MgAl–LDH, which has the guidance for the design of heterojunction catalysts and promotes the practical application of MgAl–LDH in photocatalytic region.

CeO2-based thin-film electrolyte membranes for intermediate temperature SOFCs: Direct electrophoretic deposition on the supporting anode from additive-modified suspensions

In this work, direct electrophoretic deposition (EPD) of thin-film Ce0.8Sm0.2O1.9 (SDC) electrolyte on porous nonconductive NiO–BaCe0.8Sm0.2O3 (BCS) and NiO-SDC substrates is studied. To improve the electrolyte sintering, the suspensions for EPD have been modified by the addition of Co3O4, TiO2, and Al2O3 oxides in the amount of 2, 2 and 5 mol. %, respectively. The high zeta potential values, necessary for the stable deposition, have been achieved by the introduction into the suspensions a nanosized SDC powder (10 wt %), obtained by laser evaporation. Dense composite electrolyte membranes up to 30 μm in thickness have been obtained after sintering at 1450 °C for 5 h. The influence of the sintering additives on the electrical properties of the films are studied. In SOFC mode, the effects of increasing the open circuit voltage (OCV) (1.06–0.92 V at the temperatures of 650–750 °C) are demonstrated as a consequence of the formation of a Ba-rich phase caused by the diffusion from the NiO-BCS substrate during sintering, which blocks the electron leakage current in the main SDC electrolyte. At 1450 °C, complete densification of Co-modified SDC films on the NiO-SDC anode substrate does not occur. Therefore, the sintering properties are influenced by both the Ba diffusion and the sintering additives.

Gluing Ba0.5Sr0.5Co0.8Fe0.2O3−δ with Co3O4 as a cathode for proton-conducting solid oxide fuel cells

The Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) + Co3O4 composite material is evaluated as a cathode for proton-conducting solid oxide fuel cells (H-SOFCs), which provides a new strategy to solve the thermal mismatch problem between the cathode and electrolyte without impairing the cathode performance. BSCF is a well-known cathode material for intermediate-temperature SOFCs, but its performance for H-SOFCs is unsatisfactory. One reason for the relatively low performance is the poor contact between the BSCF cathode and the electrolyte due to the high thermal expansion of BSCF. The relatively low melting point of Co3O4 is taken in this study as an advantage to bond the BSCF cathode to the electrolyte, mitigating the poor contact problem for the BSCF with the electrolyte. Furthermore, the addition of Co3O4 promotes the catalytic activity of the BSCF cathode as demonstrated by experimental studies and first-principles calculations, leading to an impressively high performance of BSCF-based cathodes for H-SOFCs.

Effect of Co3O4 on the structure and electrochemical performance of IrO2-Co3O4/Ti electrodes by first-principles calculations and experimental

The electrode materials have a decisive effect on the performance of supercapacitors. IrO2-Co3O4/Ti composite material was prepared by a thermal decomposition method. The first-principles calculation was used to study the effect of Co content on the electronic structure of IrO2-Co3O4. The influence of the Co3O4 content on the microstructure and electrochemical performance of the electrode was analyzed in detail. First-principles calculation revealed that the coating with the 50% mol Co3O4 was in a full conductive structure, and the density of states of the composite oxide with excessive content of Co3O4 would shift to a higher energy level and generate a band gap. Co doping could inhibit the crystallization of IrO2. The 50%IrO2-50%Co3O4/Ti electrode exhibited the most obvious coexistence of crystalline and amorphous phases. Besides, the addition of Co3O4 changed the microstructure to a ring-shaped branched structure, which effectively increased the specific surface area and total pore volumes of the coating. The electrode with the 50% Co3O4 had the maximum capacitance value of 979.6 F/g and maintained 90% of its initial capacitance even after 20,000 cycles of constant charge-discharge cycles, which was an ideal electrode material for supercapacitors. The results from first-principles calculation and the experiments were in consistency.

Visible-light-driven hydrogen production over ZIF-8 derived Co3O4/ZnO S-scheme based p-n heterojunctions

Photocatalytic hydrogen evolution has become an alternative tool for green fuel production from water. Nevertheless, the surface texture and vast bandgap energies are still open issues before realizing the visible light application. This study yields mesoporous hexagonal ZnO nanoparticles by calcinating the obtained zeolitic imidazolate framework (ZIF-8). In addition, the ZIF-8 is combined with a Co2+ source to yield 1.0–4.0 wt% Co3O4/ZnO p-n nanoheterojunctions by the same method. The produced heterojunctions formed 35 nm of Co3O4 nanoparticles on mesoporous ZnO exteriors and exhibited very high surface areas of 1571–1691 m2 g−1. The addition of Co3O4 to ZnO bared more exhaustive harvesting of visible light and reduced the bandgap from 3.45 to 2.76 eV. The photocatalytic hydrogen evolution over derived Co3O4/ZnO was performed in 10% aqueous glycerol solution and hexachloroplatinic acid as hole scavenger and cocatalyst precursor, correspondingly. The 3% Co3O4/ZnO verified superior H2 evolution of 2241 μmol g−1h−1, an 1834-times greater than the pure ZnO. The adjusted dose of this novel photocatalyst showed estimable reusability for five successive runs. The resourceful light-harvesting, minimizing bandgap and suppressing recombination explained the enhanced H2 evolution in the occurrence of Pt cocatalyst.

Initial Study of Magnetic Characterization of Barium Hexaferrite with the Addition of Cobalt Oxide Prepared by Powder Metallurgy Process

Co3O4 powder was added to barium hexaferrite by powder metallurgy process to determine its effect on the magnetic properties. The variation of the addition of Co3O4 are 0.0, 0.5, 1.0, 2.0, 3.0, and 5.0 wt%. Characterization and magnetic testing included density calculation, Permagraph test, and XRD were performed in order to elucidate the effect of Co3O4 addition to its structure and magnetic properties of barium hexaferrite. The magnetic density obtained was in the ranges of 3.2 - 4.35 g/cm3. From the permagraph test, it is found that the value of remanence (Br) was in between 1.18 and 1.5 kG. The value of coercivity (Hc) was in the range of 0.594 - 3.366 kOe, and the maximum product energy (BHmax) was found to be in between 0.07 and 0.48 MGOe. From the XRD analysis, it was found that two types of barium hexaferrite were formed, namely barium hexaferrite type M(BaFe12O19) and X(Ba2Fe30O46). It is concluded that the addition of the Co3O4 compound increased the value of magnetic density and decreased magnetic properties.

Development of Mn-Zn power ferrite with low losses over a broad temperature range for applications in the high frequency region of 0.5-3 MHz

Due to the rapid development of electronic devices towards high frequency, miniaturization, and high efficiency, it is imperative to develop MHz-frequency power ferrites exhibiting low loss over a broad temperature range. In this work, the broad-temperature low-loss Mn-Zn power ferrites operating in the frequency range of 0.5-3 MHz have been fabricated following the traditional oxide ceramic process. Co3O4 was added and its content was optimized to achieve the broad-temperature characteristics of power loss. The optimal Co3O4 content was determined to be 0.35 wt%. The power losses of this material are less than 30, 120, and 30 kW/m3 in the broad temperature range from 0 to 120 °C under the conditions of 500kHz/50 mT, 1MHz/50 mT, and 3MHz/10 mT, respectively. This material is an ideal material for applications in power conversion electronics at high frequencies (0.5-3 MHz). The effect of Co3O4 addition on power loss is discussed based on the compensation model of magnetocrystalline anisotropy constant. Analysis of the three parts of power loss reveals that the residual loss gradually becomes to be predominant above 1.2 MHz. The addition of Co3O4 reduces the residual loss and increases the cut-off frequency. This is ascribed to the induced uniaxial anisotropy of Co2+.

Synthesis and Characterization of Photocatalytic Activity of Hematite/ Cobalt Oxide/ Graphite Nanocomposites

In this study, at first step nanopowder particles of α-Fe2O3 (Hematite) and Co3O4 were synthesized separately thorough simple chemical method from an aqueous solution of iron (III) nitrate nonahydrate (Fe(NO3)3.9H2O) and cobalt (II) nitrate hexahydrate (Co(NO3)2.6H2O) as precursors. After that, three composites from synthesized nanopowders of Fe2O3 with 8, 16 and 24 wt.% of Co3O4 were prepared. Graphite nanopowder was added to one composition of samples in weight percentages of 1.17 and 2.35. The composition and morphology of the composites were investigated by XRD and FE-SEM, respectively. FE-SEM analysis showed that the morphology of the powders and composites were all spherical in nanoscale. The photocatalytic activity of the composites was examined by measuring the photo-degradation of the aqueous solution of methylene blue under simulated solar light. To determine the photo catalytic activity, the degradation of methylene blue (MB) in the absence of light (dark test) was taken as well. Results showed that addition of Co3O4 to Fe2O3 decrease the activity of photo-catalytic process while nano-graphite enhanced photo-catalytic process by upward of ~2 % with respect to the composite without graphite nanoparticles. Stoichiometric calculations showed that the amount of hydrogen produced by water by the composite of Fe2O3-16% Co3O4- 2.35% Graphite nanoparticles was 27 μmol H2/h.g under solar light irradiation.

Effect of molecular weight on electro – optic switching times of liquid crystal polymer doped with cobalt oxide nanoparticles

Nonlinearity liquid crystal cell which doped with Ferroelectric nanoparticles characters studied in this paper according to their eclectic absorption. Polysiloxin series with side chain liquid polymers used with side chain polymers and molecular weight ran This study consternate on polymers electro.optic characteristic with various molecular weights by using the mesogenic units and a stable polysiloxane.Suspension sensitivity or Electro-visual response to the mark of the used electric field, a real character to electric liquid crystals. The addition of Co3O4, nanoparticles to polymer rise dielectric anisotropy and minimize response times. It observed that the voltages rises with molecular weight rising, and when intensity value rise we gain voltage operating.Spectrometer used infrared measurements to locate the orientational order parameters, for liquid crystals with a side series. The orientational order parameters rely on temperature with various molecular weights and the threshold voltage.

Effects of sintering aid and atmosphere powder on the growth of (K0.5Na0.5)NbO3 single crystals fabricated by solid-state crystal growth method

(K0.5Na0.5)NbO3 (KNN) + x (= 1, 0.5, 0.05, and 0) wt%Co3O4 single crystals were fabricated by a solid-state crystal growth method with a KTaO3 seed crystal and a KNN atmosphere powder, and the effects of the sintering aid content x and the addition of Co3O4 to the atmosphere powder on the growth of the single crystals were investigated. The formation of pores in the single crystals was suppressed by a decrease of x, which, however, decreased the crystal growth length. On the other hand, dense and large KNN single crystals could be fabricated by sintering with a KNN + 5 wt%Co3O4 atmosphere at x = 0. The dielectric, ferroelectric, and piezoelectric properties of the KNN single crystals were comparable to those of reported (K,Na)NbO3 single crystals. These results would be useful for fabricating dense and large single crystals by the solid-state crystal growth method.

Probing Heteroatomic Dopant-Activity Synergy over Co3O4/Doped Carbon Nanotube Electrocatalysts for Oxygen Reduction Reaction.

Understanding and predicting how heteroatomic dopants of carbon nanotubes (CNTs)-based catalysts alter their catalytic performance at nanoscale is essential to design superior electrocatalysts for oxygen reduction reaction (ORR). This report describes findings of an investigation of the heteroatomic dopant-activity relationship for Co3O4/doped CNTs catalysts with different heteroatoms including N, O, and P atoms in ORR. By using an array of techniques to probe the structure and elementary valence of the catalysts, the incorporation of the Co3O4 nanoparticles can introduce defects into the doped CNTs, especially the N-CNTs, which should contribute to the generation of active sites. The Co3O4/N-CNTs are shown to exhibit both the highest ORR activity and stability compared with Co3O4/O-CNTs, Co3O4/P-CNTs, and Co3O4/CNTs, manifesting the synergistic correlation of Co3O4 nanoparticles, heteroatoms, and CNTs. This kind of synergy is assessed by density functional theory calculations based on the electronic properties and molecular orbitals. It is found that N, O, or P atoms can tune the charge distribution of CNTs by decreasing the lowest unoccupied molecular orbital-highest occupied molecular orbital energy gap, thus activating the adjacent C atoms. And the addition of Co3O4 will further redistribute the charge of CNTs from CNTs to Co3O4 toward enhanced ORR activity. Moreover, the Co3O4/N-CNTs catalyst exhibits a maximum structural stability due to the strong electronic interaction between Co2+ ions and N atoms, which is believed to result in its high ORR stability. Analysis of the results, along with a combined theoretical and experimental study, has provided implications for the design of catalysts with controlled activity and stability for ORR.

Novel Z-scheme Co3O4/WO3 nanocomposite performance in adsorption and photocatalytic degradation of ethylparaben and methylene blue in water

Effective removal of organic pollutants from water bodies using both adsorption and photocatalysis provides an effective solution for both ecological and environmental importance. Degradation of organics such as parabens using photocatalytic process with visible light irradiation is challenging. However, semiconductor photocatalysis based on solar radiation utilisation whose mechanism involves absorption of photons when irradiated by sunlight or illuminated light, is possible. WO3 has been exploited for its visible light utilisation whereas a novel Z–scheme photocatalyst formed when WO3 is doped with Co3O4 has shown enhanced photocatalysis and adsorption performance. Z-scheme WO3/Co3O4 semiconductor nanocomposite exhibits high photoactivity due to the suitable band gap matching between the two semiconductors as they share photoexcited electrons in the conduction band (CB) that can easily migrate to each other’s valence band (VB) to recombine with holes under solar light irradiation. In the present work, novel Co3O4/WO3 (ratio 3:7) nanocomposites were successfully synthesised via two-step route including the solvothermal process and subsequent wet impregnation method. The Co3O4/WO3 nanocomposites were applied for efficient removal of methylene blue and ethylparaben from water. Powder x-ray diffractometer (pXRD), scanning electron microscope (SEM), UV–vis diffuse reflectance spectroscopy (UV–vis DRS), x–ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) were used to characterise the prepared nanocomposites. The adsorption and photocatalytic activities of WO3 and Z-scheme Co3O4/WO3 nanocomposites (30 wt% of Co3O4) were evaluated by monitoring adsorption and photocatalytic activities of methylene blue and ethylparaben from water. The results confirmed that adsorption and photoactivity efficiencies of Co3O4/WO3 nanocomposites were higher than either WO3 or Co3O4 individually. The percentage removal efficiencies using Z-scheme Co3O4/WO3 in the degradation of methylene blue and ethylparaben were 100% and 88% respectively, after 15 min. The improvement of adsorption capability could be attributed to the increase of specific surface areas by addition of Co3O4 whereas photocatalytic performance may be attributed to lower recombination rates. Furthermore, the effects of water parameters and radical scavengers on the adsorption and degradation processes were also investigated. It was noted that were major active species in the removal of methylene blue and ethylparaben. A probable mechanism on the enhanced photocatalytic performance was proposed based on the band structure and radical trapping experiment. The novel Z-scheme Co3O4/WO3 nanocomposite developed in this study has great potential for degradation of organic pollutants in wastewater matrix. To the best of our knowledge, there is no literature that has reported the synthesis of Co3O4/WO3 nanocomposite for the application of removal of organic pollutants.

Low overpotential electrochemical CO2 reduction to formate on Co3O4–CeO2/low graphitic carbon catalyst with oxygen vacancies

We report a strategy to reduce the overpotential of CO2 electrocatalytic reduction (CO2ER) into formate by fabrication of on Co3O4–CeO2/low graphitic carbon (LGC) with oxygen vacancies. Experimental results showed that the overpotential of CO2ER into formate on Co3O4–CeO2/LGC electrode was only −0.31 V vs. RHE, and the maximum FEformate was 76.4% at −0.75 V vs RHE (−6.1 mA ▪ cm−2) with desirable stability of 45 h, displaying the maximum formate rate of 1.6 mmol▪m−2▪s−1▪C−1▪mg−1. X-ray photoelectron spectroscopy (XPS) combined with energy-dispersive X-ray spectroscopy (EDS) measurements showed that the addition of Co3O4 into CeO2/LGC led to highly concentrated oxygen vacancies that were found to be key in the enhanced activity and stable formate selectivity and the inhibited hydrogen evolution reaction (HER). Furthermore, DFT calculation demonstrated that the oxygen vacancies can effectively enhance the activation of CO2 and promote the electrochemical CO2 reduction along CO2 → CO2* → COOH*→ HCOOH path.

Co3O4-ZnO P-N Heterostructure Nanomaterials Film and its Enhanced Photoelectric Response to Visible Lights at Near Room Temperature

In this paper, Co3O4-ZnO nanomaterials with Co3O4 doping mass fractions of 0%, 2.13%, 4.13%, and 6.13% were prepared by sol-gel method. In order to explain and confirm the influence of the incorporation of Co3O4 on the surface morphology and gas sensitivity of ZnO at a relatively low gas concentration, additional studies such as XRD, XPS, SEM, EDS and UV-vis spectroscopy were performed. And its photoelectric response to 100 ppm acetone at near room temperature and visible light irradiation was studied. Due to the formation of P-N heterojunctions, the Co3O4-ZnO heterostructural nanoparticles has a highe response to low concentrations of acetone gas than undoped ZnO nanoparticles even at operating temperatures as low as 30oC. The addition of Co3O4 improves the sensitivity and selectivity of ZnO thick films. The sensitivity of the 4.13wt% Co3O4-ZnO sample to 100 ppm acetone at a working temperature of 30oC was 24.36. The light excitation effect was significantly enhanced. Under visible light irradiation, the sensitivity can reach 37.21. In addition, the Co3O4-ZnO P-N heterojunction model was combined with visible light excitation theory to further explore the mechanism of gas sensing reaction.

Effects of Co3O4 Addition on Friction and Dry Sliding Wear Characteristics of 8 mol% Yttria-Stabilized Cubic Zirconia

The aim of the present study was to investigate the influence of Co3O4 additive on the microstructure, wear, and tribological properties of 8 mol% yttria-stabilized cubic zirconia (8YSZ) using a pin-on-disk tribometer, surface profilometer, hardness tester, and a scanning electron microscopy system. Specimens were produced by doping 1-15 wt.% Co3O4 in 8YSZ using a colloidal process, sintering at 1500 °C for 1 h, and subsequent annealing at 1500 °C for 10 and 50 h. Microstructural analysis showed that Co3O4 dissolved partially in 8YSZ, with the undissolved Co3O4 precipitating as a secondary phase at the grain boundaries. Further, the addition of Co3O4 enhanced the grain size. Wear tests were carried out using an Al2O3 ball as the counterface against ceramic disk under dry sliding friction conditions at room temperature (24 °C). The wear volume of 8YSZ decreased from 0.30 to 0.11 mm3 as a result of the addition of 15 wt.% Co3O4. Additionally, friction coefficient of the 8YSZ significantly reduced from 0.55 to 0.17 at the beginning stage of the sliding after the addition of 15 wt.% Co3O4. This was because Co3O4 creates a thin lubricating layer on the friction surface. In addition, the undoped and Co3O4-doped 8YSZ specimens exhibited abrasive wear under the dry sliding friction conditions, owing to the formation and propagation of microcracks, which resulted in the removal of material from the surface. The specific wear rate of 8YSZ decreased with increasing the Co3O4 content. Thus, the addition of Co3O4 to 8YSZ improves its wear resistance and surface topography.

The influence of nanoxide additives on the characteristics of thermal decomposition of ammonium nitrate

Thermal decomposition of ammonium nitrate (NH4NO3) containing 5% (by weight) of catalytic additives in the form of metal oxides (NiO, CuO, Co2O3) has been studied. The experiment was performed by thermogravimetric analysis at a heating rate of 5°C/min to a maximum temperature of 800°C in argon atmosphere. Based on the results of DTA, physical and kinetic characteristics of thermal decomposition we analytically assessed. The addition of catalytic agents was found to lead to a decrease of onset temperature of active NH4NO3 decomposition, which promotes the reaction shift to the low-temperature region. The effect of the initiation additive manifested in a significant reduction of sample residence time within preheating stage (Δti = 5.2 min). In presence of catalytic additives the total time of thermal decomposition tf was found to decrease. The greatest change of Δtf (2.8 minutes) was recorded for the sample modified by addition of Co3O4. The maximum decrease of the average activation energy (for decomposition of 5%Co3O4/NH4NO3) was 14.2 kJ/mol.

Effect of Sintering Process with Co3O4 on the Performance of LSCF-Based Cathodes for Solid Oxide Fuel Cells

The impact of the sintering process, especially in terms of sintering temperature and sintering aid concentration, on the ohmic transport and electrode performance of (La0.80Sr0.20)0.95CoO3–δ–gadolinia-doped ceria (LSCF-GDC) cathodes is studied. The ohmic and charge-transfer kinetics exhibit a highly coupled Co3O4 concentration dependency, showing the best performances at an optimum range of 4–5 wt%. This is ascribed to small grain sizes and improved connection between particles. The addition of Co3O4 was also found to have a dominant impact on charge-transfer kinetics in the LSCF-GDC composite layer and a moderate impact on the electronic transport in the current-collecting LSCF layer. Care should be taken to avoid a formation of excessive thermal stresses between layers when adding Co3O4.

Critical Current Density, Jc Improvement of BSCCO Superconductor Tapes with Nano Co3O4 Addition

The (Bi1.6Pb0.4)Sr2Ca2Cu3Oy(Co3O4)x superconductor with addition of 0.00 - 0.05 weight per cent of Co3O4 nanoparticle with average size around 10 ± 4 nm was prepared using the co-precipitation method. Ag-sheathed Bi-2223 tapes with the highest critical current density, Jc of bulk (Bi1.6Pb0.4)Sr2Ca2Cu3Oy(Co3O4)x were fabricated using the powder-in-tube (PIT) method. The tapes were heat-treated at 845°C for 50 h. The structure, microstructure and transport critical current density (Jc) of the tapes were conducted using X-Ray diffraction, scanning electron microscopy and four point-probe respectively. The enhancement of critical current density, Jc through the addition of Co3O4 (10 nm) nanoparticles is reported. Our results show that all nanoparticles added samples for bulk and tape showed higher Jc compared to the non-added samples. The increase in Jc can be explained as the increase of the flux pinning strength by nanoparticles of Co3O4 that can act as effective pinning centres or a boost leading to enhancement of Jc in the Bi-2223 system.

Synthesis of hierarchical flower-like Co3O4 superstructure and its excellent catalytic property for ammonium perchlorate decomposition

Hierarchical flower-like cobalt tetroxide (Co3O4) was successfully synthesized via a facile precipitation method in combination with heat treatment of the cobalt oxalate precursor. The samples were systematically characterized by thermo gravimetric analysis and derivative thermo gravimetric analysis (TGA-DTG), X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and N2 adsorption-desorption measurements. The results indicate that the as-fabricated Co3O4 exhibits uniform flower-like morphologies with diameters of 8–12 μm, which are constructed by one-dimensional nanowires. Furthermore, catalytic effect of this hierarchical porous Co3O4 on ammonium perchlorate (AP) pyrolysis was investigated using differential scanning calorimetry (DSC) techniques. It is found that the pyrolysis temperature of AP shifts 142 °C downward with a 2 wt% addition content of Co3O4. Meanwhile, the addition of Co3O4 results in a dramatic reduction of the apparent activation energy of AP pyrolysis from 216 kJ mol−1 to 152 kJ mol−1, determined by the Kissinger correlation. The results endorse this material as a potential catalyst in AP decomposition.