scholarly journals Computationally Accelerated Discovery and Experimental Demonstration of Gd0.5La0.5Co0.5Fe0.5O3 for Solar Thermochemical Hydrogen Production

2021 ◽  
Vol 9 ◽  
Author(s):  
James Eujin Park ◽  
Zachary J. L. Bare ◽  
Ryan J. Morelock ◽  
Mark A. Rodriguez ◽  
Andrea Ambrosini ◽  
...  
Keyword(s):  
Water Splitting ◽  
Thermal Reduction ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Electron Effective Mass ◽  
Concentrated Solar Energy ◽  
Perovskite Materials ◽  
Oxygen Vacancy Formation ◽  
Solar Thermochemical ◽  
Xrd Patterns

Solar thermochemical hydrogen (STCH) production is a promising method to generate carbon neutral fuels by splitting water utilizing metal oxide materials and concentrated solar energy. The discovery of materials with enhanced water-splitting performance is critical for STCH to play a major role in the emerging renewable energy portfolio. While perovskite materials have been the focus of many recent efforts, materials screening can be time consuming due to the myriad chemical compositions possible. This can be greatly accelerated through computationally screening materials parameters including oxygen vacancy formation energy, phase stability, and electron effective mass. In this work, the perovskite Gd0.5La0.5Co0.5Fe0.5O3 (GLCF), was computationally determined to be a potential water splitter, and its activity was experimentally demonstrated. During water splitting tests with a thermal reduction temperature of 1,350°C, hydrogen yields of 101 μmol/g and 141 μmol/g were obtained at re-oxidation temperatures of 850 and 1,000°C, respectively, with increasing production observed during subsequent cycles. This is a significant improvement from similar compounds studied before (La0.6Sr0.4Co0.2Fe0.8O3 and LaFe0.75Co0.25O3) that suffer from performance degradation with subsequent cycles. Confirmed with high temperature x-ray diffraction (HT-XRD) patterns under inert and oxidizing atmosphere, the GLCF mainly maintained its phase while some decomposition to Gd2-xLaxO3 was observed.

CO2 Splitting in a Hot-Wall Aerosol Reactor via the Two-Step Zn/ZnO Solar Thermochemical Cycle

2009 ◽  
Author(s):  
Peter G. Loutzenhiser ◽  
M. Elena Ga´lvez ◽  
Illias Hischier ◽  
Anastasia Stamatiou ◽  
Aldo Steinfeld
Keyword(s):  
Flow Reactor ◽  
Energy Conversion Efficiency ◽  
Solar Furnace ◽  
Thermochemical Cycle ◽  
X Ray Diffraction ◽  
Concentrated Solar Energy ◽  
High Temperature Process ◽  
Solar Thermochemical ◽  
Reduction Of Co2

Using concentrated solar energy as the source of high-temperature process heat, a two-step CO2 splitting thermochemical cycle based on Zn/ZnO redox reactions is applied to produce renewable carbon-neutral fuels. The solar thermochemical cycle consists of: 1) the solar endothermic dissociation of ZnO to Zn and O2; 2) the non-solar exothermic reduction of CO2 with Zn to CO and ZnO; the latter is the recycled to the 1st solar step. The net reaction is CO2 = CO + 1/2 O2, with products formed in different steps, thereby eliminating the need for their separation. A Second-Law thermodynamic analysis indicates a maximum solar-to-chemical energy conversion efficiency of 39% for a solar concentration ratio of 5000 suns. The technical feasibility of the first step of the cycle has been demonstrated in a high-flux solar furnace with a 10 kW solar reactor prototype. The second step of the cycle is experimentally investigated in a hot-wall quartz aerosol flow reactor, designed for in-situ quenching of Zn(g), formation of Zn nanoparticles, and oxidation with CO2. The effect of varying the molar flow ratios of the reactants was investigated. Chemical conversions were determined by gas chromatography and X-ray diffraction. Chemical conversions of Zn to ZnO of up to 88% were obtained for a residence time of ∼ 3.05 s. For all of the experiments, the reactions primarily occurred outside the aerosol jet flow on the surfaces of the reaction zone.

scholarly journals Solar Thermochemical Hydrogen Production via Terbium Oxide Based Redox Reactions

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Rahul Bhosale ◽  
Anand Kumar ◽  
Fares AlMomani
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Water Splitting ◽  
Thermal Reduction ◽  
Terbium Oxide ◽  
Heat Recuperation ◽  
Solar Thermochemical ◽  
Oxidation By Water ◽  
Heat Released ◽  
Reaction Equilibrium

The computational thermodynamic modeling of the terbium oxide based two-step solar thermochemical water splitting (Tb-WS) cycle is reported. The 1st step of the Tb-WS cycle involves thermal reduction of TbO2into Tb and O2, whereas the 2nd step corresponds to the production of H2through Tb oxidation by water splitting reaction. Equilibrium compositions associated with the thermal reduction and water splitting steps were determined via HSC simulations. Influence of oxygen partial pressure in the inert gas on thermal reduction of TbO2and effect of water splitting temperature (TL) on Gibbs free energy related to the H2production step were examined in detail. The cycle (ηcycle) and solar-to-fuel energy conversion (ηsolar-to-fuel) efficiency of the Tb-WS cycle were determined by performing the second-law thermodynamic analysis. Results obtained indicate thatηcycleandηsolar-to-fuelincrease with the decrease in oxygen partial pressure in the inert flushing gas and thermal reduction temperature (TH). It was also realized that the recuperation of the heat released by the water splitting reactor and quench unit further enhances the solar reactor efficiency. AtTH=2280 K, by applying 60% heat recuperation, maximumηcycleof 39.0% andηsolar-to-fuelof 47.1% for the Tb-WS cycle can be attained.

scholarly journals Histidine Decorated Nanoparticles of CdS for Highly Efficient H2 Production via Water Splitting

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3738
Author(s):  
Fumiya Tojo ◽  
Manabu Ishizaki ◽  
Shigeru Kubota ◽  
Masato Kurihara ◽  
Fumihiko Hirose ◽  
...  
Keyword(s):  
Cadmium Sulfide ◽  
Water Splitting ◽  
Solvothermal Method ◽  
H2 Production ◽  
Sem Analysis ◽  
Cds Nanoparticles ◽  
H2 Evolution ◽  
X Ray Diffraction ◽  
Hexagonal Wurtzite Crystal Structure ◽  
Xrd Patterns

Pure cadmium sulfide and histidine decorated cadmium sulfide nanocomposites are prepared by the hydrothermal or solvothermal method. Scanning electron microscopy (SEM) analysis shows that the particle sizes of pure cadmium sulfide (pu/CdS) and histidine decorated cadmium sulfide prepared by the hydrothermal method (hi/CdS) range from 0.75 to 3.0 μm. However, when a solvothermal method is used, the particle size of histidine decorated cadmium sulfide (so/CdS) ranges from 50 to 300 nm. X-ray diffraction (XRD) patterns show that all samples (pu/CdS, hi/CdS and so/CdS) have a hexagonal wurtzite crystal structure but so/CdS has a poor crystallinity compared to the others. The as-prepared samples are applied to photocatalytic hydrogen production via water splitting and the results show that the highest H2 evolution rate for pu/CdS and hi/CdS are 1250 and 1950 μmol·g−1·h−1, respectively. On the other hand, the so/CdS sample has a rate of 6020 μmol·g−1·h−1, which is about five times higher than that of the pu/CdS sample. The increased specific surface area of so/CdS nanoparticles and effective charge separation by histidine molecules are attributed to the improved H2 evolution.

Microstructure and Compression Behavior of Ti3Al Based Ti-Al-V Ternary Alloys

2008 ◽  
Vol 1128 ◽  
Author(s):  
Tohru Takahashi ◽  
Ayumu Kiyohara ◽  
Daisuke Masujima ◽  
Jun Nagakita
Keyword(s):  
Ternary Alloys ◽  
Chemical Compositions ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
Compression Behavior ◽  
Arc Melting ◽  
Solid Solution Range ◽  
Coarse Grains ◽  
Metallographic Observation ◽  
Xrd Patterns

AbstractThe ordered alloy phase of Ti3Al shows a rather wide solid solution range in aluminum and also in vanadium. Several Ti-Al-V ternary alloys have been prepared to investigate the alloy composition effect upon microstructure, crystallography, and mechanical characteristics. The materials containing 75, 70, and 65 at.% titanium, and 0 or 5 at.% vanadium were prepared by arc melting. Metallographic observation has revealed that the binary Ti-Al alloys contained somewhat coarse grains with about 100 μm grain diameter. In contrast to this, ternary alloys containing 5 at.% vanadium showed smaller grained microstructures with grain diameters around 15 μm. The grain size could not be adjusted to a unified value in the present study. X-ray diffraction study and microanalysis showed that the alloys contained single phase α2. Not every possible diffraction peak of the D019 ordered structure has been observed in the XRD patterns. The lattice parameters, a and c, were observed to decrease as the aluminum content increased and also when vanadium was added. Compression tests have been performed at various temperature ranging from an ambient temperature up to 1300K on rectangular parallelepiped specimens with 2mm×2mm×3mm dimensions. Alloys containing more aluminum showed higher strength, and vanadium addition enhanced the strength of the alloys. In some alloys deformability and strength are both enhanced by vanadium addition in some alloys. Temperature dependence of strength showed a little variation upon chemical compositions.

Iron-Containing Yttria-Stabilized Zirconia System For Two-Step Thermochemical Water Splitting

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Nobuyuki Gokon ◽  
Takayuki Mizuno ◽  
Yumiko Nakamuro ◽  
Tatsuya Kodama
Keyword(s):  
Water Splitting ◽  
Thermal Reduction ◽  
Inert Atmosphere ◽  
Yttria Stabilized Zirconia ◽  
Temperature Reaction ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Solid Materials ◽  
X Ray ◽  
High Temperature Reaction

An iron-containing yttria-stabilized zirconia (YSZ) or Fe-YSZ was found to be a promising working redox material for the thermochemical two-step water-splitting cycle. The Fe-YSZ was formed by a high-temperature reaction between YSZ doped with more than 8mol%Y2O3 and Fe3O4 supported on the YSZ at 1400°C in an inert atmosphere. The formed Fe-YSZ reacted with steam to generate hydrogen at 1000°C. The oxidized Fe-YSZ was reactivated by a thermal reduction at 1400°C in an inert atmosphere. The alternative O2 and H2 generations in the repeated two-step reactions and the X-ray diffraction and chemical analysis studies on the solid materials indicated that the two-step water splitting was associated with a redox transition between Fe2+–Fe3+ ions in the cubic YSZ lattice.

Hydrogen Production by Solar Thermochemical Water-Splitting/Methane-Reforming Process

Solar Energy ◽  
2003 ◽  
Author(s):  
Tatsuya Kodama ◽  
Yoshiyasu Kondoh ◽  
Atsushi Kiyama ◽  
Ken-Ich Shimizu
Keyword(s):  
Hydrogen Production ◽  
Metal Oxide ◽  
Water Splitting ◽  
Thermal Energy ◽  
Experimental Studies ◽  
Reduction Process ◽  
Thermal Reduction ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Solar Thermochemical

Two different routes of solar thermochemical hydrogen production are reviewed. One is two-step water splitting cycle by using a metal-oxide redox pair. The first step is based on the thermal reduction of metal oxide, which is a highly endothermic process driven by concentrated solar thermal energy. The second step involves water decomposition with the thermally-reduced metal oxide. The first thermal reduction process requires very-high temperatures, which may be realized in sun-belt regions. Another hydrogen production route is solar reforming of natural gas (methane), which can convert methane to hydrogen via calorie-upgrading by using concentrated solar thermal energy. Solar reforming is currently the most advanced solar thermochemical process in sun belt. There is also possibility for the solar reforming to be applied for worldwide solar concentrating facilities where direct insolation is weaker than that in sun belt. Our experimental studies to improve the relevant catalytic technologies are shown and discussed.

Design of a Lab-Scale Rotary Cavity-Type Solar Reactor for Continuous Thermal Reduction of Volatile Oxides Under Reduced Pressure

2009 ◽  
Author(s):  
Marc Chambon ◽  
Ste´phane Abanades ◽  
Gilles Flamant
Keyword(s):  
High Temperature ◽  
Metal Oxide ◽  
Thermal Reduction ◽  
Reduction Reaction ◽  
High Specific Surface Area ◽  
Reduced Pressure ◽  
Water Steam ◽  
Solar Reactor ◽  
Concentrated Solar Energy ◽  
Solar Thermochemical

The investigated two-step MxOy/ MxOy−1 solar thermochemical cycles consist of two redox reactions. Net result is watersplitting with concentrated solar energy as the source of high temperature process heat: 1)Solarreduction:MxOy→MxOy−1+1/2O2(about1700°Catatmosphericpressure,endothermal)2)Hydrolysis:MxOy−1+H2O→MxOy+H2(about400°C,exothermal) The MxOy−1 species produced in reaction (1) is gaseous in the case of the ZnO/Zn cycle. The oxide (ZnO) is injected in a solar thermochemical reactor and undergoes a thermal reduction reaction (oxygen release). Dilution/quenching with a neutral gas at the reactor exit yields nanoparticles of metal by condensation. The particles have a high specific surface area that leads to a high reactivity in the 2nd step. The reduced species (Zn) can then be fed to another reactor to react with water steam. The reaction produces pure H2 and forms the original metal oxide. A high-temperature lab-scale solar reactor prototype was designed, constructed and operated, allowing continuous metal oxide processing under controlled atmosphere. It is based on a cavity-type rotating receiver absorbing solar radiation. The reactant powder is injected continuously inside the cavity and the produced particles (Zn) are recovered in a downstream filter. The solar reduction of ZnO has been achieved, the reaction yields were quantified, and a first concept of solar reactor was qualified.

Structural and Magnetic Hysteresis Properties of Co-Zr Substituted Hexagonal Barium Ferrites

2015 ◽  
Vol 7 (1) ◽  
pp. 1346-1351
Author(s):  
Ch.Gopal Reddy ◽  
Ch. Venkateshwarlu ◽  
P. Vijaya Bhasker Reddy
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Magnetic Hysteresis ◽  
Grain Morphology ◽  
Hexagonal Structure ◽  
Ion Composition ◽  
X Ray Diffraction ◽  
Ceramic Method ◽  
Barium Ferrites ◽  
Xrd Patterns

Co-Zr substituted M-type hexagonal barium ferrites, with chemical formula BaCoxZrxFe12-2xO19 (where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), have been synthesized by double sintering ceramic method. The crystallographic properties, grain morphology and magnetic properties of these ferrites have been investigated by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM). The XRD patterns confirm the single phase with hexagonal structure of prepared ferrites. The magnetic properties have been investigated as a function of Co and Zr ion composition at an applied field in the range of 20 KOe. These studies indicate that the saturation magnetization (Ms) in the samples increases initially up to the Co-Zr composition of x=0.6 and decreases thereafter. On the other hand, the coercivity (Hc) and Remanent magnetization (Mr) are found to decrease continuously with increasing Co-Zr content. This property is most useful in permanent magnetic recording. The observed results are explained on the basis of site occupation of Co and Zr ions in the samples.

scholarly journals Waste and Solar Energy: An Eco-Friendly Way for Glass Melting

2021 ◽  
Vol 5 (2) ◽  
pp. 16
Author(s):  
Isabel Padilla ◽  
Maximina Romero ◽  
José I. Robla ◽  
Aurora López-Delgado
Keyword(s):  
Solar Energy ◽  
Environmental Sustainability ◽  
Raw Materials ◽  
Glass Melting ◽  
Glass Network ◽  
X Ray Diffraction ◽  
X Ray ◽  
Concentrated Solar Energy ◽  
Calcium Source ◽  
The Aluminum Industry

In this work, concentrated solar energy (CSE) was applied to an energy-intensive process such as the vitrification of waste with the aim of manufacturing glasses. Different types of waste were used as raw materials: a hazardous waste from the aluminum industry as aluminum source; two residues from the food industry (eggshell and mussel shell) and dolomite ore as calcium source; quartz sand was also employed as glass network former. The use of CSE allowed obtaining glasses in the SiO2-Al2O3-CaO system at exposure time as short as 15 min. The raw materials, their mixtures, and the resulting glasses were characterized by means of X-ray fluorescence, X-ray diffraction, and differential thermal analysis. The feasibility of combining a renewable energy, as solar energy and different waste for the manufacture of glasses, would highly contribute to circular economy and environmental sustainability.

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