Ternary Spinel Research Articles

FeCoNi Ternary Spinel Oxides Nanosheets as High Performance Water Oxidation Electrocatalyst

AbstractFeCoNi spinel oxides nanosheets array directly supported on the Ni foam substrate were prepared via a facile wet chemical method with 2‐methylimidazole as a structure directing agent and subsequently annealing. The as‐prepared 0.1Fe−CoNiO/NF offers high intrinsic catalytic activity, high surface area and good conductivity, resulting in enhanced activity for the oxygen evolution reaction (OER) in the alkaline solution. It demonstrates an ultralow overpotentials of 240 mV at 10 mA cm−2 and a small Tafel slope of 36.8 mV dec−1, with attractive durability during long‐term operation in 1 M KOH solution.

Surface Reorganization on Electrochemically-Induced Zn-Ni-Co Spinel Oxides for Enhanced Oxygen Electrocatalysis.

Herein, we highlight redox-inert Zn2+ in spinel-type oxide (ZnX Ni1-X Co2 O4 ) to synergistically optimize physical pore structure and increase the formation of active species on the catalyst surface. The presence of Zn2+ segregation has been identified experimentally and theoretically under oxygen-evolving condition, the newly formed VZn -O-Co allows more suitable binding interaction between the active center Co and the oxygenated species, resulting in superior ORR performance. Moreover, a liquid flow Zn-air battery is constituted employing the structurally optimized Zn0.4 Ni0.6 Co2 O4 nanoparticles supported on N-doped carbon nanotube (ZNCO/NCNTs) as an efficient air cathode, which presents remarkable power density (109.1 mW cm-2 ), high open circuit potential (1.48 V vs. Zn), excellent durability, and high-rate performance. This finding could elucidate the experimentally observed enhancement in the ORR activity of ZnX Ni1-X Co2 O4 oxides after the OER test.

Intrinsic energy-storage mechanism of low crystallinity nickel-cobalt sulfide as anode material for supercapacitors

NiCo2S4 (NCS) is a ternary spinel sulfide widely applied in supercapacitors and hybrid supercapacitors. Several electrochemical reaction formulas have so far been proposed in last decade. However, the energy storage mechanism and electrochemical behavior of NCS in alkaline electrolytes are still not fully understood. In this study, the interactions between hydroxide and NCS with low crystallinity are investigated through electrochemical testing and both surface and structure characterization. Compared to previous reports, electrochemical desulfurization is first introduced in electrochemical charge storage to reveal the intrinsic energy-storage mechanism of NCS in alkaline electrolyte. The highest specific capacitance of NCS reaches 666.27 F g−1 at 5 A g−1, originating from the irreversible phase transition during the activation process. The long cycle stability retains 65.29% of the highest specific capacitance after 10 000 cycles, attributed to the transformation product (nickel-cobalt dihydroxide) without further phase change after the activation process. In sum, clarification of the intrinsic energy-storage mechanism of NCS with low crystallinity can be helpful for future preparation of anode materials for applications in alkaline supercapacitors, batteries, and hybrid devices.

Newborn screening for Morquio syndrome: Results from the 8-plex assay for 70,000 newborns

Cu-Ni-Al ternary spinel solid solution catalysts with different Al content are prepared by the solid-phase ball milling method. The characterizations with XRD, H2-TPR, BET and XPS, and catalytic performance testing are carried out to study the effects of Al content on the physicochemical properties of the Cu-Ni-Al spinels and their sustained release catalytic performances in methanol steam reforming for hydrogen production. Characterization results show a significant increase in the specific surface area and pore volume of the catalysts with increasing the Al content (Al = 2, 3, 4) at a constant Cu/Ni molar ratio of 0.95:0.05. At the same time, both the cell parameters and crystallite sizes of Cu-Ni-Al spinel solid solutions decrease, and the catalysts become difficult to be reduced. Furthermore, the content of spinel Ni2+ increases slightly while the spinel Cu2+ decreases significantly, leading to a declined total content of spinel Cu2+ plus Ni2+. The results also indicate that the presence of Ni2+ inhibits the formation of spinel Cu2+. Surface analysis results show that the increase of Al content transforms the catalyst surface composition from Cu-rich to Al-rich, and the surface spinel Cu2+ decreases, but it is still higher than the spinel bulk. The catalyst testing results show that as the Al content in the catalysts increases, the initial activity increases notably, and the CO selectivity decreases, but too much Al results in an inferior catalytic stability. In general, the catalyst with an Al = 3 shows a better catalytic performance in terms of activity and stability. The results of this paper demonstrate that there is an optimal Al content for the Cu-Ni-Al spinel solid solutions used as the sustained release catalysts, playing a crucial role in obtaining high catalytic stability.

Developing Indium-based Ternary Spinel Selenides for Efficient Solid Flexible Zn-Air Batteries and Water Splitting.

Exploring economic, efficient, and corrosion-resistant oxygen electrocatalysts contributes to further development of zinc-air batteries and overall water splitting. Herein, a novel ternary spinel CoIn2Se4 nanomaterial, with Co2+ and In3+ occupying the tetrahedral and octahedral sites of the crystalline structure, has been fabricated using a facile and environment-friendly method. Moreover, CoIn2Se4 nanosheets outperform pristine CoSe2 and In2Se3 in catalyzing both oxygen evolution reaction (an overpotential of 315 mV at 10 mA cm-2) and oxygen reduction reaction (an onset overpotential of 0.88 V). The reduced charge resistance and increased active site exposure ratio contribute to the superior performance of CoIn2Se4. Moreover, density of theory (density functional theory-DFT) calculations suggest a significantly reduced reaction energy barrier after introducing indium into the spinel, and therefore the reaction kinetics are facilitated. Based on the advantages described above, CoIn2Se4 is used as the air cathode for a solid flexible zinc-air battery (FZAB). The system displays an efficient performance that outperforms the Pt@Ir/C catalyst: a significantly enhanced specific capacity of 733 mAh gZn-1, a high energy density of 931 Wh kg-1, and an excellent flexibility with long cycle life performance (over 400 cycles). The CoIn2Se4-based two-series-connected FZABs successfully power light-emitting diode (LED) screens for over 10 h. Meanwhile, CoIn2Se4 also shows a significantly enhanced hydrogen evolution reaction (HER) performance than other samples. Finally, the CoIn2Se4-based electrolyzer shows an efficient overall water-splitting performance with high stability. This work demonstrates that the indium-based ternary selenides show promising applications in developing renewable energy and water-splitting devices.

Multicomponent Spinel Oxide Solid Solutions: A Possible Alternative to Platinum Group Metal Three-Way Catalysts

Single-phase quaternary spinel solid solutions, Cu0.05Ni0.95AlyCr2–yO4 (0 ≤ y ≤ 2.0), were prepared over the whole range of y by a polymerized complex method to study as platinum group metal-free three-way catalysts (TWC). Most conventional binary and/or ternary spinel oxides lose their NO reduction activity in the presence of water vapor and/or after high-temperature aging. In contrast, the present quaternary system with y = 1.8, which was aged at 900 °C for 25 h, preserved high activity even under a wet gas stream (5% H2O) simulating real TWC conditions. Comprehensive structural analyses via X-ray absorption fine structure and X-ray Rietveld analysis showed that, in the quaternary system, Cu and Cr prefer to occupy the tetrahedral site and the octahedral site, respectively, whereas Ni and Al are distributed across both sites. The partial replacement of Cr by Al increased the specific surface area from 7 m2 g–1 (y = 0) to 36 m2 g–1 (y = 1.8), which is a common feature of the NiAl2O4-based spinel platform...

Efficient CO2 to CO conversion at moderate temperatures enabled by the cobalt and copper co-doped ferrite oxygen carrier

Abstract Chemical looping technology holds great potential on efficient CO2 splitting with much higher CO production and CO2 splitting rate than photocatalytic processes. Conventional oxygen carrier requires high temperature (typically 850–1000 °C) to ensure sufficient redox activity, but the stable and high CO2 conversion is favored at a lower temperature, leading to the degrading on the reaction kinetics as well as the low CO production and CO2 splitting rate. In this paper, we prepared several ternary spinels and demonstrated their performance for chemical looping CO2 splitting at moderate temperatures. Using the promotion effect of Cu to cobalt ferrite reduction and reversible phase change of the reduced metals, Cu0.4Co0.6Fe2O4 exhibits high CO2 splitting rate (~144.6 µmol g–1 min–1) and total CO production (~9100 µmol g–1) at 650 °C. The high performance of this earth-abundant spinel material is also consistent in repeated redox cycles, enabling their potential in industrial use.

Anchoring Spinel MnCo2S4 on Carbon Nanotubes as Efficient Counter Electrodes for Quantum Dot Sensitized Solar Cells

Ternary spinel MnCo2S4 was anchored on carbon nanotubes (CNTs) via a two-step method of precursor preparation followed by ion exchange, and employed as efficient counter electrodes for quantum dot ...

First-Principles Study of Structural, Elastic, Electronic and Optical Properties of Zinc Ferrite Spinel

Structural, electronic,elastic and optical properties of ternary spinel oxides ZnFe2O4 have been studied by using first-principles calculation. The results show that all elastic constants are consistent with the mechanical stability criteria for cubic crystals, which indicated that ternary spinel oxides ZnFe2O4 are mechanically stable. The perfect spinel ZFO has the properties of direct bandgap semiconductor, which decreases with the increase of pressure.The DOS and Mulliken overall analysis shows that the Zn-O bonds and Fe-O bonds are covalent, and the Zn-O bond is stronger than the Fe-O bond. The results of the calculation show that the optical properties are in good agreement with the recent experimental results.

Facile synthesis of ternary spinel Co–Mn–Ni nanorods as efficient bi-functional oxygen catalysts for rechargeable zinc-air batteries

Facile synthesis of high efficient bi-functional oxygen catalysts is important for large-scale application of rechargeable metal-air batteries. Herein, an ethanol-water mediated co-precipitation approach is applied to fabricate Co–Mn–Ni (CMN) ternary spinel oxides with uniform 1D structure. Their catalytic activities toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are investigated by the rotating ring-disk electrode (RRDE) techniques. The ternary spinel oxide with the Co/Mn/Ni atomic ratio of 2:3:1 (CMN-231) exhibits the best bi-functional activities among the as-prepared ternary, binary and unitary spinel oxides (△E is as low as 0.88 V), which can be attributed to its reasonable element composition, mesoporous nanorod structure, strong oxygen-adsorption ability and good charger-transfer capability. In addition, the CMN-231 catalyst demonstrates a strong stability during long-term operation. This well-designed catalyst is applied in a homemade zinc-air battery, and exhibits good charge–discharge performances (voltage gap is 0.9 V at 50 mA cm−2) and remarkable cycling stability.

Comparative study on ternary spinel cathode Zn–Mn–O microspheres for aqueous rechargeable zinc-ion batteries

We demonstrate the cation ratio-controlled synthesis of ZnMn2O4 and Zn1.67Mn1.33O4 aggregated microspheres. The carbonate precursor was synthesized by a solvothermal reaction, and then completely converted to oxide by calcination at 600 °C with a controlled cationic ratio. The prepared ternary oxide has a nanoparticle-aggregated morphology and uniform size distribution. The electrochemical properties were investigated by cyclic voltammetry and constant current charge-discharge measurements. The Zn1.67Mn1.33O4 electrode reveals better performance for Zn2+ storage than the other, delivering 175 mA h g−1 after 40 cycles. After the electrochemical test, ex situ analysis was conducted to identify the Zn2+ storage mechanisms. From these results, we confirm that the Zn1.67Mn1.33O4 cathode is a promising Zn2+ storage material for environmental friendly aqueous rechargeable Zn-ion batteries.

Photoactive Zn-Air-Batteries Suing Cobalt Oxide As the Photocatalyst at the Cathode

Herein, we introduce a new design for the photoactive Zn-air batteries (ZABs). Spinel-type cobalt oxide is synthesized, coated on a transparent conductive indium tin substrate (Co3O4/ITO), and used as a photoactive cathode. The optical absorption of the Co3O4/ITO electrode show direct and indirect optical bandgaps for which the direct and indirect band gap values are 2.20 eV and 1.35 eV, respectively. These values are in the visible light region (1.8-3.1 eV)1. Under the exposure of visible light, the Co3O4/ITO exhibits ca. 30% higher current density than that under dark condition and provides the lower overpotentials of oxygen evolution reaction (OER) and oxygen oxidation reaction (ORR) around 10% - 20% as compared to those under dark condition. By assembling the photoactive ZAB cell, the higher battery performance is clearly observed under the visible light illumination. This new idea can open up opportunities in many applications requiring the conversion and storage of energy within a single cell. Reference Walsh, A.; Ahn, K.-S.; Shet, S.; Huda, M. N.; Deutsch, T. G.; Wang, H.; Turner, J. A.; Wei, S.-H.; Yan, Y.; Al-Jassim, M. M., Ternary cobalt spinel oxides for solar driven hydrogen production: Theory and experiment. Energy & Environmental Science 2009, 2 (7), 774-782. Figure 1

Facile Preparation of Cadmium Gallate Nanoparticles as a Novel Photocatalyst with High Efficiency and Stability

In this work, we introduced a facile approach for preparing cadmium gallate (CdGa2 O4 nanoparticles, and we first studied the photocatalytic properties of this ternary spinel oxide. Through a solvothermal process for the formation of precursor and the subsequent calcination process for recrystallization, CdGa2 O4 nanoparticles with diameter of ca. 12 nm were synthesized. They were characterized by using X-ray diffraction patterns and electron microscopy images. UV-visible diffuse absorption spectroscopy was also conducted; its spectra indicate that CdGa2 O4 nanoparticles have strong but small blue-shift absorption relative to that of the bulk samples. Moreover, the CdGa2 O4 nanoparticles could photocatalytically decompose rhodamine B (RhB) molecules with high efficiency in aqueous solution under ultraviolet irradiation. Notably, this novel photocatalyst exhibited outstanding recycling stability, and it retained almost the same capacity in the fourth photocatalytic cycle. We deduce that the high photocatalytic performance results from the large specific surface area, energetic photoinduced carriers, and inherent stability.

Mn Cations Control Electronic Transport in Spinel CoxMn3–xO4 Nanoparticles

Understanding the mechanisms of charge transport in ternary and higher order spinels would enable design principles for enhancing their electronic and electrochemical properties for energy applications. Here we investigate the ternary CoxMn3–xO4 spinel system and determine the relationship between electronic properties and cation site occupation, based on the octahedral site, donor–acceptor formalization introduced in the polaron hopping model. We employ synchrotron X-ray emission spectroscopy to characterize the donor–acceptor cation pairs in the lattice. We find that the stochiometric volcano trend in electronic conductivity correlates well with the concentration of Mn4+/Mn3+ hopping pairs, while the concentration of Mn3+/Mn2+ pairs is unchanged with stoichiometry. We also find that Co does not directly contribute to conductivity; however, the Co does create configurational disorder that leads to the generation of hopping pairs for Mn at octahedral sites. From these results we conclude that Mn4+/Mn3+ pa...

MgSc2 Se4 -A Magnesium Solid Ionic Conductor for All-Solid-State Mg Batteries?

Recently, the ternary spinel selenide MgSc2 Se4 was proposed to have high magnesium ion mobility and is therefore an interesting potential candidate as a solid electrolyte in magnesium secondary batteries. To test the properties of the material, a modified solid-state reaction was used to synthesize pure MgSc2 Se4 . Electrochemical characterizations identified detrimental high electronic conductivities, which limit its application as a Mg-conducting solid electrolyte. Two methods were attempted to lower electronic conductivities, including the implementation of Se-rich phases and aliovalent doping, however, with no sufficient improvement. Based on the mixed conducting properties of MgSc2 Se4 , a reversible insertion/extraction of Mg2+ into the spinel structure could be demonstrated.

Ternary nickel cobalt manganese spinel oxide nanoparticles as heterogeneous electrocatalysts for oxygen evolution and oxygen reduction reaction

Multimetallic nanostructure spinels composed of nickel, cobalt, and manganese ions were synthesized and their bifunctional catalytic activity towards oxygen evolution and oxygen reduction reaction in alkaline pH is reported. Three different compositions, namely, NiCoMnO4, Ni1.5Co0.75Mn0.75O4, and Ni2Co0.5Mn0.5O4 were prepared by a simple template-free hydrothermal route followed by a thermal treatment in air at 600 °C. The ORR/OER activity and the stability of these ternary metal oxides strongly depend on the composition of transition metals. The best performing Ni1.5Co0.75Mn0.75O4 catalyst exhibits modest OER and ORR activity with an overpotential difference (ΔE = EORR-EOER) of 0.79 V vs. RHE between two reactions in alkaline solution, comparable to expensive and supported IrO2, Pt catalysts. Electrochemical studies and extensive physical characterizations indicated that amount of nickel substituted in the crystal lattice influence the bifunctional catalytic activity of the studied ternary metal oxide compositions.

Modified bluing treatment to produce nickel-cobalt-iron spinel oxide with promoted oxygen-evolving performance.

A rapid modified bluing treatment approach was proposed for the facile synthesis of a ternary NiCoFe spinel oxide catalyst. Benefitted from the synergy of multi-elements, the enriched high-valence species and good structural stability, highly efficient and durable oxygen-evolving performance was achieved, offering an economic route for the batch preparation of advanced electrocatalysts.

Transition metal based CuxNiyCoz-x-yO4 spinel composite solar selective absorber coatings for concentrated solar thermal applications

Solar selective absorber coatings, combining of nanostructured, ternary transition metal spinel structure and composite oxides were prepared by a series of transition metal (Co, Ni and Cu) based nitrate salts. A single-layered structure of crystalline phase spinel-type oxide AB2O4 in the framework of simple wet chemical route and dip coating method was prepared in the crystalline structure of CuxNiyCoz-x-yO4. The X-ray diffraction profile of the oxide film was found to coincide with that of crystalline [Cu2+0.31Co3+0.16Co2+0.53]A[Cu2+0.17Ni3+0.16Co3+1.67]BO4 in the ICDD database. Precursor salts were heated at a particular temperature to form hydroxy nitrate solution followed by suitable solvent with different binders to form adherent sol for dip coating technique. By optimizing sol concentration, withdrawal speed and annealing temperature, uniform absorber layer with solar absorptance of 0.91 and emittance of 0.14 were achieved in a single layer coating with a composite oxide formation. The optical, structural and morphological properties of the optimized coatings of single layer CuxNiyCoz-x-yO4 spinel and composite oxide have been characterized by UV–Vis–NIR spectrophotometer, emissometer, X-ray diffraction, field emission - scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy.

Facile synthesis of hierarchical porous ZnMn2O4 rugby-balls on Ni foam for lithium-ion batteries with enhanced electrochemical properties

Hierarchical porous ZnMn2O4 rugby-balls on Ni foam were first synthesized via a hydrothermal method and then an annealing process. The ZnMn2O4 rugby-balls were composed of interconnected nanosheets of about 25 nm. The growth mechanism is also proposed. In addition, the unique structure of hierarchical porous ZnMn2O4 rugby-balls on Ni foam exhibited superior electrochemical performances including high specific capacity, long cyclic stability and good rate capability. At a constant current density of 100 mA g−1, the initial discharge and charge capacities were 1584 mAh g−1 and 1114 mAh g−1 respectively, after 100 cycles, the reversible capacity could remain 614 mAh g−1. These results demonstrate great potential of hierarchical porous ZnMn2O4 rugby-balls on Ni foam in advanced LIBs. Furthermore, this method may provide a novel route for the synthesis of a series of hierarchical porous ternary spinel oxides rugby-balls.

X-ray emission spectroscopy: an effective route to extract site occupation of cations.

Cation site occupation is an important determinant of materials properties, especially in a complex system with multiple cations such as in ternary spinels. Many methods for extracting the cation site information have been explored in the past, including analysis of spectra obtained through K-edge X-ray absorption spectroscopy (XAS). In this work, we measure the effectiveness of X-ray emission spectroscopy (XES) for determining the cation site occupation. As a test system we use spinel phase CoxMn3-xO4 nanoparticles contaminated with CoO phases because Co and Mn can occupy all cation sites and the impurity simulates typical products of oxide syntheses. We take advantage of the spin and oxidation state sensitive Kβ1,3 peak obtained using XES and demonstrate that XES is a powerful and reliable technique for determining site occupation in ternary spinel systems. Comparison between the extended X-ray absorption fine structure (EXAFS) and XES techniques reveals that XES provides not only the site occupation information as EXAFS, but also additional information on the oxidation states of the cations at each site. We show that the error for EXAFS can be as high as 35% which makes the results obtained ambiguous for certain stoichiometries, whereas for XES, the error determined is consistently smaller than 10%. Thus, we conclude that XES is a superior and a far more accurate method than XAS in extracting cation site occupation in spinel crystal structures.