Syngas production via CO2 reforming of methane over plasma assisted synthesized Ni‐Co/Al2O3‐ZrO2 nanocatalysts with different Ni‐loadings

Ni‐Co/Al₂O₃‐ZrO₂ nanocatalysts with 5, 10 and 15 wt.% nominal Ni content have been prepared by impregnation followed by a non‐thermal plasma treatment, characterized and tested for dry reforming of methane. For nanocatalysts characterization the following techniques have been used: XRD, FESEM, TEM, EDX dot‐mapping, BET, FTIR and XPS. The dry reforming of methane was carried out at different temperatures (550‐850 °C) using a feed mixture of CH₄:CO₂ (1:1). Among the nanocatalysts studied, the catalyst with the medium Ni content (10 wt.%) was the most active in dry reforming of methane. This higher activity exhibited by Ni‐Co/Al₂O₃‐ZrO₂ catalyst with medium Ni content (10 wt.% ) can be attributed to small and well dispersed particles of Ni within the catalyst. Apart from the narrow surface particle size distribution in the case of Ni(10 wt.%)‐Co/Al₂O₃‐ZrO₂, the presence of small active components with average size of 7.5 nm is proposed to be the reason for the superior performance of the catalyst. Ni(10 wt.%)‐Co/Al₂O₃‐ZrO₂ nanocatalyst had maximum surface area and the lower surface area was observed in the case of Ni(5 wt.%)‐Co/Al₂O₃‐ZrO₂ and Ni(15 wt.%)‐Co/Al₂O₃‐ZrO₂ due to the formation of the larger agglomeration and higher mean particle size of nickel particles, respectively. Although, GHSV enhancment had inverse effect on product yield but yield reduction for Ni‐Co/Al₂O₃‐ZrO₂ catalyst with 10 wt.% Ni was less drastic at high GHSVs. According to XRD and XPS, existence of NiAl₂O₄ confirms strong interaction between Ni and support but higher loadings of Ni resulted in less NiAl₂O₄; loser interaction between support and active phase. Small particles of active components and well‐defined dispersion of them in Ni(10 wt.%)‐Co/Al₂O₃‐ZrO₂ nanocatalyst resulted in stability of the catalyst for either feed conversion or H₂/CO molar ratio. Copyright © 2013 John Wiley & Sons, Ltd.     

Stability evaluation of ethanol dry reforming on Lanthania‐doped cobalt‐based catalysts for hydrogen‐rich syngas generation

Catalytic stability with time‐on‐stream is an important aspect in ethanol dry reforming (EDR) since catalysts could encounter undesirable deterioration arising from deposited carbon. This work examined the promotional effect of La on 10%Co/Al₂O₃ in terms of activity, stability, and characteristics. Catalysts were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman, and X‐ray photoelectron spectroscopy (XPS) measurements whilst catalytic EDR performance of La‐promoted and unpromoted 10%Co/Al₂O₃ prepared via wet impregnation technique was investigated at 973 K for 72 h using a stoichiometric feed ratio (C₂H₅OH/CO₂ = 1/1). La promoter substantially enhanced both metal dispersion and metal surface area from 0.11% to 0.64% and 0.08 to 0.43 m² g^?1, respectively. Ethanol and CO₂ conversions appeared to be stable within 50 to 72 h after experiencing an initial activity drop. The conversion of C₂H₅OH and CO₂ for La‐promoted catalyst was about 1.65 and 1.34 times greater than unpromoted counterpart in this order. The carbonaceous deposition was considerably decreased from 55.6% to 36.8% with La promotion due to La₂O₂CO₃ intermediate formation. Additionally, 3%La‐10%Co/Al₂O₃ possessed greater oxygen vacancies acting as active sites for CO₂ adsorption and hence increasing carbon gasification. Even though graphitic and filamentous carbons were formed on used catalyst surface, La‐addition diminished graphite formation and increased the reactiveness of amorphous carbon.     

Submicron‐sized Sb2O3 with hierarchical structure as high‐performance anodes for Na‐ion storage

Submicron‐sized Sb₂O₃ with hierarchical structure was successfully prepared via a synthesis of one‐step solvothermal chemical route. Na‐ion storage performance of Sb₂O₃ material was investigated. Sb₂O₃ anode exhibits a high reversible capacity (approximately 350 mAh/g) and stable cycle stability (greater than 95%) over 100 cycles at 100 or 200 mA/g. A full battery with Sb₂O₃ anode and P2‐Na_2/3Ni_1/3Mn_1/2Ti_1/6O₂ (PTO) cathode indicated a high energy density of 216.6 Wh/kg.     

Surface modification of LiNi0.5Co0.2Mn0.3O2 cathode materials with Li2O‐B2O3‐LiBr for lithium‐ion batteries

LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523) cathode material suffers from phase transformation and electrochemical performance degradation as its main drawbacks, which are strongly dependent on the surface state of NCM523. Herein, an effective surface modification approach was demonstrated; namely, the fast lithium‐ion conductor (Li₂O‐B₂O₃‐LiBr) was coated on NCM523. The Li₂O‐B₂O₃‐LiBr coating layer as a protecting shell can prevent NCM523 particles from corrosion by the acidic electrolyte, leading to a superior discharge capacity, rate capability, and cycling stability. At room temperature, the Li₂O‐B₂O₃‐LiBr–coated NCM523 exhibited an excellent capacity retention of 87.7% after 100 cycles at the rate of 1 C, which is remarkably better than that (29.8%) without the uncoated layer. Furthermore, the coating layer also increased the discharge capacity of NCM523 cathode material from 68.7 to 117.0 mAh g^?1 at 5 C. Those can be attributed to the reduction in the electrode polarization and improvement in the electrode conductivity, which was supported by electrochemical impedance spectroscopy and cyclic voltammetry measurements.     

Syngas production from methane dry reforming via optimization of tungsten trioxide-promoted mesoporous γ-alumina supported nickel catalyst

Syngas production via dry reforming of methane was conducted over 5 wt%Ni + xWO₃/γ-Al₂O₃ (x = 1, 3, 5, 7, or 9 wt%) catalysts at 700 °C and ambient pressure for 7.5 h in a tubular fixed-bed reactor. Textural, morphological, and catalytic properties were investigated in relation to the weight percent of tungsten trioxide loading. The physicochemical properties of the catalysts were evaluated using XRD, N₂-physisorption, TGA, H₂-TPR, CO₂-TPD, NH₃-TPD, SEM, EDX, and Raman techniques. N₂-physisorption analysis showed that tungsten trioxide promoter had a minor impact on the textural properties upon varying its weight percentage loading. With increasing tungsten trioxide loading, the total amount of reducible NiO-interacting species was increased over the catalyst surface. 5Ni+5WO₃/γ-Al₂O₃ catalyst showed stable 79% CH₄ conversions and 83% CO₂ conversion with the lowest carbon deposition due to the presence of stable metallic Ni species (derived from reducible NiAl₂O₄ and NiWOAl), the highly acidic sites, and moderate basic sites.     

Synergic influence of potassium loading and plasma-treatment on anti-coke property of K-Promoted bimetallic NiCoNiAl2O4 nanocatalyst applied in O2-Enhanced dry reforming of CH4

K-promoted bimetallic NiCoNiAl₂O₄ nanocatalysts with various loadings of potassium (0, 0.25, 0.75 and 1.25) were fabricated by utilization of hybrid sol-gel plasma method. Nanocatalysts were assessed by XRD, FESEM, AFM, EDX, BET-BJH and TPR analyses. Also, used nanocatalysts were tested by TG-DTG, XRD, and EDX analyses. Nanocatalysts were appraised in O₂-enhanced dry reforming of CH₄. XRD patterns indicated that by increasing of K loadings, amorphous behaviour was amplified. However, intensity of all peaks was decreased but reduction amount in the case of prone planes for coke formation slightly was greater than others. Great surface area and uniform dispersion was gained for the non-promoted nanocatalyst (NCK0A (SGP)), but surface covering by K addition led to the unsuitable properties. Owing to the EDX and FESEM, for K rich samples, surface area was decreased, average particle size got larger and dispersion of particles got worse. Noted attributes led to the lower yields of syngas for K rich samples. Despite the adverse impact of K such as lower activity, covering of defected site, enhanced reducibility and improving the rate of carbon gasification, led to the improved stability and less amount of coke deposition for K rich ones. Efficiency of NCK0A (SGP) and 0.25 wt% K promoted one (NCK0.25A (SGP)) were close to each other, but lower amount of deposited coke and more stable performance was gained for NCK0.25A (SGP). However, H₂ yields of NCK0A (SGP) and NCK0.25A (SGP) at first tests of TOF was close to each other but due to the 48 h test, they reached to 73 and 75%, respectively. Yields drop of NCK0A (SGP) was 8.5% while for NCK0.25A (SGP) was just 2.8%. Based on opposite tendency of TOF and yields and also, excellent properties of NCK0.25A (SGP) such as high enough activity, stable performance and high coke resistance, it seems that NCK0.25A (SGP) is a promising nanocatalyst for O₂-enhanced dry reforming of CH₄. H₂ yield of NCK0.25A (SGP) at 850 °C was 87%. Small average particle size, tunable morphology, larger surface area and optimum amount of appended K, were the reasons which led to the superior performance of NCK0.25A (SGP).     

Direct conversion of syngas to DME over CuO–ZnO–Al2O3/HZSM‐5 nanocatalyst synthesized via ultrasound‐assisted co‐precipitation method: New insights into the role of gas injection

In this study, direct synthesis of dimethyl ether (DME) is conducted over a bifunctional CuO–ZnO–Al₂O₃/H Zeolite Socony Mobil‐5 (HZSM‐5) nanocatalyst. A hybrid method of ultrasound‐assisted co‐precipitation is used for the synthesis of catalysts, and the effect of gas injection during sonication is investigated. The physicochemical characteristics of the catalysts are analysed by X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), particle size distribution (PSD), energy dispersive X‐ray (EDX), Brunauer–Emmett–Teller (BET) and Fourier‐transformed infrared (FTIR) methods. In the absence of gas injection, the acetate‐based catalysts have a better morphology and higher surface area than the nitrate‐based catalyst. Gas injection significantly changes the morphology and structural properties of the acetate‐based catalyst. High surface area, narrow PSD and better dispersion of small CuO crystals are obtained in a gas‐injected synthesized sample. DME synthesis experiments showed that the CO conversion and DME selectivity are correlated with surface area, nanocatalyst particle size and its dispersion. The gas‐injected CuO–ZnO–Al₂O₃/HZSM‐5 nanocatalyst that has the highest surface area and the smallest dispersed particles showed more than 70% DME selectivity. The gas‐injected CuO–ZnO–Al₂O₃/HZSM‐5 nanocatalyst exhibited high stability in terms of CO conversion and DME yield over 1440‐min time on a stream test at 275°C, 40 bar and 18 000 cm³ g.h^?1. Copyright © 2014 John Wiley & Sons, Ltd.     

Various calcium loading and plasma-treatment leading to controlled surface segregation of high coke-resistant Ca-promoted NiCo–NiAl2O4 nanocatalysts employed in CH4/CO2/O2 reforming to H2

High coke-resistant Ca-promoted NiCo–NiAl₂O₄ nanocatalysts with different calcium loading (0, 0.25, 0.5 and 1.5 wt%) were synthesized via hybrid sol-gel-plasma method. Synthesized samples were applied in the CH₄/CO₂/O₂ reforming to H₂ reactions. Analyses revealed that the calcium addition caused the lower surface area, non-uniform distribution and larger particle size. Therefore, higher activity and yield were found for the nanocatalyst without calcium while catalytic activity and yield were descended for the other ones. This trend was according to the covering effect of calcium and undesirable effect of calcium over the surface area and particle size distribution. But owing to the enhanced coke gasification rate of Ca-rich samples, by increasing of Ca amount, coke deposition was descended and stable performance was promoted. Due to the time on stream performance (TOS) during the 48 h and at 750 °C, 1.5 wt% Ca-promoted NiCo–NiAl₂O₄ (NCCa1.5A (SGP)) was stable, but demonstrated the lower yield. Moreover, 0.25 wt% Ca-promoted NiCo–NiAl₂O₄ nanocatalyst (NCCa0.25A (SGP)) was illustrated the higher yield in comparison with NCCa1.5A (SGP). It must be noted that just 2.7% deactivation for H₂ yield was detected for NCCa0.25A (SGP) during the 48 h TOS performance. H₂ yield of the NCCa0.25A (SGP) at 850 °C was 84%. Based on the reverse trends of the yield and TOS performance, NCCa0.25A (SGP) was able to present as a promising nanocatalyst for CH₄/CO₂/O₂ reforming to H₂. Moreover, this offer was ascribed to the excellent coke resistance and superior catalytic performance of NCCa0.25A (SGP).     

Hierarchical Zn1.67Mn1.33O4/graphene nanoaggregates as new anode material for lithium‐ion batteries

Cubic spinel type Zn_1.67Mn_1.33O₄ porous sub‐micro spheres were synthesized by the calcination of solvothermally prepared Zn_xMn_1 ? xCO₃ precursor powders and evaluated as new anode materials for Li‐ion batteries for the first time. Each sphere exhibited aggregated morphology, constructed entirely from nanoparticles with a primary particle size of 11 nm. Electrochemical investigations and ex‐situ transmission electron microscopy analyses revealed that the reaction mechanism of obtained Zn_1.67Mn_1.33O₄ nanoaggregates is the combined conversion and alloying reaction, similar to that of ZnMn₂O₄ systems. In favor of the uniform porous sphere structure, these resulting Zn_1.67Mn_1.33O₄ nanoaggregates enabled the mitigation of volume change upon cycling. In addition, graphene composites with Zn_1.67Mn_1.33O₄ nanoaggregates were fabricated to improve electrical conductivity, simply by adding graphenes during solvothermal reaction for the formation of Zn_xMn_1 ? xCO₃ precursors. Zn_1.67Mn_1.33O₄/graphene composites showed a capacity of 670 mA h g^?1 higher than that of pure Zn_1.67Mn_1.33O₄ (518 mA h g^?1) after 200 cycle at a current density of 100 mA g^?1.     

Dry reforming of methane on Ni/mesoporous-Al2O3 catalysts: Effect of calcination temperature

Catalysts of Ni supported on home-made mesoporous alumina (Ni/M-Al₂O₃) were prepared via facile incipient impregnation method and calcined under different temperature (500–800 °C). Compared with catalysts of Ni supported on commercial alumina, they showed much higher conversion and lower carbon deposition in methane dry reforming (DRM). Among the catalysts, Ni/M-Al₂O₃-700 exhibited the highest DRM activity, with 77.6% CH₄ conversion and 85.4% CO₂ conversion at 700 °C. TPR revealed that almost all the Ni was in the form of NiAl₂O₄ spinel after calcination at 700 °C. Due to the strong metal-support interaction of NiAl₂O₄ structure, the Ni crystal size of Ni/M-Al₂O₃-700 after reduction was around 5 nm. TGA and TEM results showed its carbon deposition after 20 h DRM test was only 3.8% and mainly in the form of amorphous carbon. This work indicates that the formation of NiAl₂O₄ spinel is beneficial to activity and stability towards DRM reaction and controlling calcination temperature is crucial.     

Evaluation of redox performance of silver and transition metal‐doped ternary ceria oxides for thermochemical splitting of CO2

Synthesis of Ce_0.9M_0.05Ag_0.05O_2‐δ materials (where, M = Ni, Zn, Mn, Fe, Cu, Cr, Co, Zr) via coprecipitation of hydroxide method and examination of these materials toward multiple thermochemical CO₂ splitting (CS) cycles is reported in this paper. Physical properties of the derived Ce_0.9M_0.05Ag_0.05O_2‐δ materials were estimated by analyzing the calcined powder using a powder X‐ray diffractometer (PXRD) and scanning electron microscope (SEM). The redox reactivity (RR) of each Ce_0.9M_0.05Ag_0.05O_2‐δ material was also evaluated by conducting high‐temperature thermogravimetric experiments. The inclusion of Ag as an active dopant has improved the RR of all the Ce_0.9M_0.05Ag_0.05O_2‐δ materials as compared with the Ce_0.9M_0.1O_2‐δ materials. Among all the Ce_0.9M_0.05Ag_0.05O_2‐δ materials, Zn5Ag5Ce material was capable of releasing highest amount of O₂ 84.1 μmol O₂/g·cycle and the Cr5Ag5Ce material indicated maximum CO production (151.6 μmol CO/g·cycle). The uppermost CO/O₂ molar ratio equal to 1.89 was observed in case of Cr5Ag5Ce material. The quantity of O₂ released and CO produced by Cr5Ag5Ce material was superior as compared with CeO₂¹ by 30.7 μmol O₂/g·cycle and 62.8 μmol CO/g·cycle, respectively.     

Electrospun porous Fe2O3 nanotubes as counter electrodes for dye‐sensitized solar cells

Porous Fe₂O₃ nanostructures were synthesized through electrospinning of Fe (NO₃)₃/polyvinylpyrrolidone followed by calcination in air. The morphology of the resultant Fe₂O₃ was tuned by changing the ratio between Fe (NO₃)₃ and the polymer matrix. The performance of these nanostructures as counter electrodes in dye‐sensitized solar cells (DSSCs) was investigated. It was found that nanotubes exhibit significantly higher catalytic efficiency toward reducing I^?/I₃^? electrolytes than nanorods and nanobelts, showing a photoelectric conversion efficiency of 4.0%, also superior to a range of transition metal oxides. Furthermore, the nanotube‐based counter electrode showed lower resistance than other Fe₂O₃ nanostructures. These results were attributed to the high specific surface area (90.2 m² g^?1) of the nanotubes, which provides a large reaction site and can promote the charge transfer at the electrode/electrolyte interfaces. The low cost and ease of mass production make Fe₂O₃ nanotube a promising candidate to replace Pt as the counter electrode in DSSCs.     

Fabrication of oxide pellets containing lumped Gd2O3 using Y2O3‐stabilized ZrO2 for burnable absorber fuel applications

In this paper, the fabrication of novel burnable absorber fuel concepts with oxide pellets, containing either a lumped Gd₂O₃ rod, a mini‐pellet, or a spherical particle in the centerline of the oxide pellet, is investigated to propose the lumped Gd₂O₃ burnable absorber fuel concept to improve nuclear fuel performance with longer fuel cycle lengths and better fuel utilization. The unique characteristic of the lumped Gd₂O₃ burnable absorber fuel is its high spatial self‐shielding factor that reduces its burnout rate and, therefore, improves the reactivity control. Oxide pellets containing lumped Gd₂O₃ were fabricated by using a combination of cold isostatic pressing and microwave sintering at 1500°C to understand the potential technical issues in the fabrication of duplex burnable absorber fuel. The effect of the sintering temperature on the densification and phase transformation of 8 wt.% yttria‐stabilized zirconia, a surrogate for UO₂, was investigated. Spherical Gd₂O₃ particles were fabricated by the drip casting of a Gd₂O₃‐based Na alginate solution. The fabrication of duplex oxide pellets by using presintered Gd₂O₃ mini‐pellets resulted in internal cracks at the interface between the Gd₂O₃ and 8 wt.% yttria‐stabilized zirconia layers because of the mismatch of their densification. However, the formation of interfacial cracks was eliminated by controlling the initial sintered density of the lumped Gd₂O₃.     

A novel high specific capacity lithium‐ion capacitor battery with Li+‐doped Ni0.64Al0.64Mn0.56O2 prepared by coprecipitation method as cathode active material

Lithium‐ion capacitor battery is a late‐model energy storage system. It can combine the lithium‐ion battery with the capacitor to ensure that it has a high specific capacity and excellent large‐current discharge performance. In this paper, a novel Li⁺‐doped Ni_0.64Mn_0.64Al_0.56O₂ is synthesized by coprecipitation method and as a capacitor active material with commercialized LiNi_1/3Co_1/3Mn_1/3O₂ in different proportions forms the cathode of the lithium‐ion capacitor batteries. By analyzing the results of physical property characterization, when the mass ratio is 7:3, the crystal size of cathode material is less than 2 μm with uniform porous distribution. And, through electrochemical tests, the cathode has the greatest excellent reversibility, the lowest‐charge resistance, and the fastest‐lithium‐ion diffusion rate. Specific capacity can reach 196.34 mAh g^?1 at 0.5°C and, even at 5°C current density, it also can be 67.63 mAh g^‐1. After 110 times charge and discharge cycles, capacity retention of this cathode material at 5°C still can be over 85%.     

Conductivity features of semiconducting tungsten‐phosphate glasses

The ac conductivity of 70WO₃–30P₂O₅ glass composition prepared by melt quenching was first studied in the temperature range 25°C to 350°C. The conductivity of the semiconducting glass is investigated with various electrodes (Pt and Ga‐Ag alloy). It is shown that the type of spectrum of cell impedance depends on the chosen electrodes. The influence of the samples geometry on the conduction is established. The influence of gas atmosphere (argon, oxygen, and air of different humidity) on electrical conductivity of tungsten‐phosphate glass on is studied for the first time. A mixed electronic‐ionic conductivity in the 70WO₃–30P₂O₅ glass is found out. The transport numbers are shown as a function of temperature. Ionic and electronic contribution to the conduction is estimated. The electrical conductivity of glass undergoes changes from 8.6 × 10^?8 (25°C) to 3.1 × 10^?4 S/cm (300°C) in air.     

Enhanced performance of alpha‐Fe2O3 nanoparticles with optimized graphene coated layer as anodes for lithium‐ion batteries

A series of different α‐Fe₂O₃ nanoparticles composites containing different amounts of graphene coatings have been successfully prepared using a simple electrostatic self‐assembly (ESA) method. The structure and electrochemical properties of these α‐Fe₂O₃@graphene composites have been investigated. The α‐Fe₂O₃ nanoparticles composite containing 40 wt% graphene coating exhibits the highest specific capacity (385 mAh g^?1) under 1000 mA g^?1, resulting in superior cycle stability with no downward trend after 500 cycles. These results demonstrate that graphene coatings can be used to enhance the electrochemical properties and morphological stability of α‐Fe₂O₃ nanoparticles as anodic materials for high performance lithium‐ion batteries (LIBs). The low‐energy self‐assembly method employed in the paper has good potential for the broad‐scale preparation of other graphene‐modified materials because of its simplicity and the relatively low temperature conditions.     

The optimization of Ni–Al2O3 catalyst with the addition of La2O3 for CO2–CH4 reforming to produce syngas

A series of La₂O₃–NiO–Al₂O₃ catalysts promoted by different loading of lanthanum were prepared via the hydrolysis-deposition method to improve the catalytic performance of nickel-based catalyst for CO₂–CH₄ reforming. The catalysts were characterized by N₂ adsorption - desorption, XRD, H₂-TPR, TG-DTG, TEM, Raman and TPH techniques. Results showed that the precursor of active component was mainly in the form of NiAl₂O₄ spinel, which almost disappeared after reduction process from XRD characterization, suggesting well reduction performance. The catalyst with La loading of 0.95 wt% (La–Ni-1) presented a small average Ni grain size of 7.71 nm and exhibited well catalytic performance at 800 °C, with CH₄ conversion of 94.37%, CO₂ conversion of 97.15%, H₂ selectivity of 75.01% and H₂/CO ratio of 0.92. The Ni grain size of La–Ni-1 increased only 5.84% to 8.16 nm after performance test, which was lower than that of others and indicated a well structure stability. Additionally, the strong carbon diffraction peak over La–Ni-0.5 and La–Ni-2 catalysts suggested the presence of crystalline carbon species accumulated on the catalysts, while there was no carbon peak over La–Ni-1 sample. A 150 h stability test for La–Ni-1 demonstrated that the conversion of CH₄ was around 95%, higher than that of La–Ni-0 (without lanthanum addition) and La–Ni-4 (with La content of 3.82 wt%). The carbon deposition rate of La–Ni-1 was only 1.63 mg/(g_cat·h), lower than that of La–Ni-4 (2.20 mg/(g_cat·h)), showing both high activity and well stability. Therefore, the “confinement effect” of La₂O₃ to Ni crystalline grain would inhibit the sintering of active component, prevent the carbon deposition, and improve the catalytic reforming performance.     

Thermoelectric properties of P‐doped and V‐doped Fe2O3 for renewable energy conversion

The effect of P and V contents on the microstructure and thermoelectric properties of Fe_2‐xM_xO₃ (M: P and V; 0 ≤ x ≤ 0.01) is studied. Higher P and V contents result in increases of both the grain size and density, thus increasing the electrical conductivity. The absolute values of the Seebeck coefficients of the Fe_2‐xP_xO₃ and Fe_2‐xV_xO₃ increase with increasing P and V contents up to x = 0.0075 and 0.005, respectively, and then decrease with further increase of its concentration. The addition of a small amount of V (0.005) to Fe₂O₃ leads to a marked increase in both the electrical conductivity and Seebeck coefficient. This means that the introduction of a small amount of V is highly effective for improving the thermoelectric properties of Fe₂O₃. Copyright © 2013 John Wiley & Sons, Ltd.     

Hydrogen‐rich syngas production from chemical looping steam reforming of bio‐oil model compound: Effect of bimetal on LaNi0.8M0.2O3 (M = Fe,Co, Cu,and Mn)

Chemical looping steam reforming (CLSR) of acetic acid as bio‐oil model compound is a suitable way to produce hydrogen‐rich syngas. The LaNiO₃ and LaNi_0.8M_0.2O₃ (M = Fe, Co, Mn, and Cu) perovskites were prepared via the sol‐gel method. The perovskites were characterized by X‐ray diffraction (XRD), thermogravimetry (TG), and test activity of hydrogen‐rich syngas in a fixed bed. XRD and TG results showed that the coke generation on LaNi_0.8Fe_0.2O₃ needs a lower decomposition temperature, and a stable structure was appeared after reaction. The activity order of hydrogen‐rich syngas on five types of perovskite is LaNi_0.8Fe_0.2O₃ > LaNi_0.8Co_0.2O₃ > LaNiO₃ > LaNi_0.8Mn_0.2O₃ > LaNi_0.8Cu_0.2O₃ at 650°C, mole ratio of steam/carbon (2:1), and sample mixture flow (GHSV = 34 736 g of feed/(g catalyst h)). The CLSR of acetic acid with LaNi_0.8Fe_0.2O₃ at GHSV = 43 992 g of feed/(g catalyst h) showed good stability. Correlated to experimental results, the adsorption energy of steam and acetic acid on five types of perovskite were calculated using density functional theory (DFT). The adsorption energy of steam (?0.61 eV) and acetic acid (?0.93 eV) of LaNi_0.8Fe_0.2O₃ is maximum. This value of DFT calculation is well explained in the experimental results.     

Achieving high performance for aluminum stabilized Li7La3Zr2O12 solid electrolytes for all solid‐state Li‐ion batteries: A thermodynamic point of view

For the solid‐state reaction synthesis of Al containing Li₇La₃Zr₂O₁₂, various precursors have been used. Since there is a lack of general agreement for choosing precursors, a quantitative approach to build a consensus is required. In this study, a thermodynamic point of view for selecting the precursors in the field of Li₇La₃Zr₂O₁₂ synthesis was covered according to the Gibbs free energy and enthalpy change of precursors' decomposition reactions. In terms of Gibbs free energy change calculations, LiOH, La(OH)₃, and Al(OH)₃ were favorable whereas, LiOH, La₂O₃, and Al(OH)₃ were the preferred precursors for the enthalpy change calculations. Pellets prepared by using the favored precursors calculated from enthalpy change showed improved densification, higher ionic conductivity (2.11 × 10^?4 S/cm), and lower activation energy (0.23 eV) compared with Gibbs free energy change. As a thermodynamically favored aluminum precursor, Al(OH)₃ was discussed in the present study and hinders the ionic conductivity in comparison to Al₂O₃.