Roles of Cationic and Elemental Calcium in the Electro-Reduction of Solid Metal Oxides in Molten Calcium Chloride

Previous work, mainly from this research group, is re-visited on electrochemical reduction of solid metal oxides, in the form of compacted powder, in molten CaCl2, aiming at further understanding of the roles of cationic and elemental calcium. The discussion focuses on six aspects: 1.) debate on two mechanisms proposed in the literature, i. e. electro-metallothermic reduction and electro-reduction (or electro-deoxidation), for the electrolytic removal of oxygen from solid metals or metal oxides in molten CaCl2; 2.) novel metallic cavity working electrodes for electrochemical investigations of compacted metal oxide powders in high temperature molten salts assisted by a quartz sealed Ag/AgCl reference electrode (650 ºC- 950 ºC); 3.) influence of elemental calcium on the background current observed during electrolysis of solid metal oxides in molten CaCl2; 4.) electrochemical insertion/ inclusion of cationic calcium into solid metal oxides; 5.) typical features of cyclic voltammetry and chronoamperometry (potentiostatic electrolysis) of metal oxide powders in molten CaCl2; and 6.) some kinetic considerations on the electrolytic removal of oxygen.

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Influences of graphite anode area on electrolysis of solid metal oxides in molten salts

Journal of Solid State Electrochemistry ◽

10.1007/s10008-014-2645-2 ◽

2014 ◽

Vol 18 (12) ◽

pp. 3317-3325 ◽

Cited By ~ 10

Author(s):

Hualin Chen ◽

Xianbo Jin ◽

Linpo Yu ◽

George Z. Chen

Keyword(s):

Metal Oxides ◽

Molten Salts ◽

Solid Metal ◽

Graphite Anode ◽

Anode Area

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TWO-PHASE FLAMES A POTENTIAL METHOD FOR MANUFACTURING SUBMICRON METAL OXIDE POWDERS

International Journal of Energetic Materials and Chemical Propulsion ◽

10.1615/intjenergeticmaterialschemprop.v4.i1-6.480 ◽

1997 ◽

Vol 4 (1-6) ◽

pp. 486-489

Author(s):

N. D. Ageyev ◽

S. Kyro ◽

Yu. Kostishin

Keyword(s):

Metal Oxide ◽

Potential Method ◽

Two Phase ◽

Oxide Powders

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Metal-oxide based ammonia gas sensors: A review

Nanoscience &Nanotechnology-Asia ◽

10.2174/2210681210999200718005402 ◽

2020 ◽

Vol 10 ◽

Author(s):

Priya Gupta ◽

Savita Maurya ◽

Narendra Kumar Pandey ◽

Vernica Verma

Keyword(s):

Metal Oxide ◽

Metal Oxides ◽

Gas Sensor ◽

Gas Sensors ◽

Review Paper ◽

Gas Sensing ◽

Gas Sensitivity ◽

Ammonia Gas ◽

Ammonia Sensing ◽

Ammonia Gas Sensors

: This review paper encompasses a study of metal-oxide and their composite based gas sensors used for the detection of ammonia (NH3) gas. Metal-oxide has come into view as an encouraging choice in the gas sensor industry. This review paper focuses on the ammonia sensing principle of the metal oxides. It also includes various approaches adopted for increasing the gas sensitivity of metal-oxide sensors. Increasing the sensitivity of the ammonia gas sensor includes size effects and doping by metal or other metal oxides which will change the microstructure and morphology of the metal oxides. Different parameters that affect the performances like sensitivity, stability, and selectivity of gas sensors are discussed in this paper. Performances of the most operated metal oxides with strengths and limitations in ammonia gas sensing application are reviewed. The challenges for the development of high sensitive and selective ammonia gas sensor are also discussed.

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Thermochemical Energy Storage Performance Analysis of (Fe,Co,Mn)Ox Mixed Metal Oxides

Catalysts ◽

10.3390/catal11030362 ◽

2021 ◽

Vol 11 (3) ◽

pp. 362

Author(s):

Yabibal Getahun Dessie ◽

Qi Hong ◽

Bachirou Guene Lougou ◽

Juqi Zhang ◽

Boshu Jiang ◽

...

Keyword(s):

Energy Storage ◽

Metal Oxide ◽

Metal Oxides ◽

Redox Reaction ◽

Gas Flow ◽

Oxygen Exchange ◽

Engineering Industry ◽

Oxide Material ◽

Oxide Materials ◽

Uptake Ratio

Metal oxide materials are known for their ability to store thermochemical energy through reversible redox reactions. Metal oxides provide a new category of materials with exceptional performance in terms of thermochemical energy storage, reaction stability and oxygen-exchange and uptake capabilities. However, these characteristics are predicated on the right combination of the metal oxide candidates. In this study, metal oxide materials consisting of pure oxides, like cobalt(II) oxide, manganese(II) oxide, and iron(II, III) oxide (Fe3O4), and mixed oxides, such as (100 wt.% CoO, 100 wt.% Fe3O4, 100 wt.% CoO, 25 wt.% MnO + 75 wt.% CoO, 75 wt.% MnO + 25 wt.% CoO) and 50 wt.% MnO + 50.wt.% CoO), which was subjected to a two-cycle redox reaction, was proposed. The various mixtures of metal oxide catalysts proposed were investigated through the thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), energy dispersive X-ray (EDS), and scanning electron microscopy (SEM) analyses. The effect of argon (Ar) and oxygen (O2) at different gas flow rates (20, 30, and 50 mL/min) and temperature at thermal charging step and thermal discharging step (30–1400 °C) during the redox reaction were investigated. It was revealed that on the overall, 50 wt.% MnO + 50 wt.% CoO oxide had the most stable thermal stability and oxygen exchange to uptake ratio (0.83 and 0.99 at first and second redox reaction cycles, respectively). In addition, 30 mL/min Ar–20 mL/min O2 gas flow rate further increased the proposed (Fe,Co,Mn)Ox mixed oxide catalyst’s cyclic stability and oxygen uptake ratio. SEM revealed that the proposed (Fe,Co,Mn)Ox material had a smooth surface and consisted of polygonal-shaped structures. Thus, the proposed metallic oxide material can effectively be utilized for high-density thermochemical energy storage purposes. This study is of relevance to the power engineering industry and academia.

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Effect of nano-metal oxides (ZnO, Al2O3, CuO, and TiO2) on the corrosion behavior of a nano-metal oxide/epoxy coating applied on the copper substrate in the acidic environment

Applied Nanoscience ◽

10.1007/s13204-021-01806-7 ◽

2021 ◽

Author(s):

Mehdi Eskandari ◽

Ali Shanaghi ◽

Mahsa Kamani ◽

Mehdi Asadi Niari

Keyword(s):

Metal Oxide ◽

Metal Oxides ◽

Corrosion Behavior ◽

Copper Substrate ◽

Epoxy Coating ◽

Acidic Environment

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Prebiotic studies on the interaction of zirconia nanoparticles and ribose nucleotides and their role in chemical evolution

International Journal of Astrobiology ◽

10.1017/s1473550421000033 ◽

2021 ◽

Vol 20 (2) ◽

pp. 142-149

Author(s):

Avnish Kumar Arora ◽

Pankaj Kumar

Keyword(s):

Electron Microscopy ◽

Metal Oxide ◽

Metal Oxides ◽

Chemical Evolution ◽

Ribonucleic Acid ◽

Zirconium Oxide ◽

Origins Of Life ◽

Neutral Ph ◽

Interaction Studies

AbstractStudies on the interaction of biomolecules with inorganic compounds, mainly mineral surfaces, are of great concern in identifying their role in chemical evolution and origins of life. Metal oxides are the major constituents of earth and earth-like planets. Hence, studies on the interaction of biomolecules with these minerals are the point of concern for the study of the emergence of life on different planets. Zirconium oxide is one of the metal oxides present in earth's crust as it is a part of several types of rocks found in sandy areas such as beaches and riverbeds, e.g. pebbles of baddeleyite. Different metal oxides have been studied for their role in chemical evolution but no studies have been reported about the role of zirconium oxide in chemical evolution and origins of life. Therefore, studies were carried out on the interaction of ribonucleic acid constituents, 5′-CMP (cytidine monophosphate), 5′-UMP (uridine monophosphate), 5′-GMP (guanosine monophosphate) and 5′-AMP (adenosine monophosphate), with zirconium oxide. Synthesized zirconium oxide particles were characterized by using vibrating sample magnetometer, X-Ray Diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy. Zirconia particles were in the nanometre range, from 14 to 27 nm. The interaction of zirconium oxide with ribonucleic acid constituents was performed in the concentration range of 5 × 10−5–300 × 10−5 M. Interaction studies were carried out in three mediums; acidic (pH 4.0), neutral (pH 7.0) and basic (pH 9.0). At neutral pH, maximum interaction was observed. The interaction of zirconium oxide with 5′-UMP was 49.45% and with 5′-CMP 67.98%, while with others it was in between. Interaction studies were Langmurian in nature. Xm and KL values were calculated. Infrared spectral studies of ribonucleotides, metal oxide and ribonucleotide–metal oxide adducts were carried out to find out the interactive sites. It was observed that the nitrogen base and phosphate moiety of ribonucleotides interact with the positive charge surface of metal oxide. SEM was also carried out to study the adsorption. The results of the present study favour the important role of zirconium oxide in concentrating the organic molecules from their dilute aqueous solutions in primeval seas.

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Nanostructured TiO2-Based Composites for Light Absorption

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.975.207 ◽

2014 ◽

Vol 975 ◽

pp. 207-212

Author(s):

Dayse I. dos Santos ◽

Olayr Modesto Jr. ◽

Luis Vicente A. Scalvi ◽

Americo S. Tabata

Keyword(s):

Metal Oxide ◽

Light Absorption ◽

Structural Characteristics ◽

Sol Gel ◽

Second Phase ◽

X Ray Diffraction ◽

Two Phase ◽

X Ray ◽

Oxide Powders

Metal oxide nanocomposites were prepared by two different routes: polyol and sol-gel. Characterization by X ray diffraction showed that the first process produces directly a two-phase material, while the sol-gel powder never showed second phase below 600°C. Light spectroscopy of the treated powders indicated similarities for the processed materials. Although the overall material compositions are about the same, different structural characteristics are found for each processing. With the exception of Ti-Zn materials, all the double metal oxide powders showed higher absorbance than either TiO2 powder.

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