Electrochemical Synthesis of Rare Earth Ceramic Oxide Coatings

Golden, Teresa D.; Shang, Yajuan; Wang, Qi; Zhou, Ting

doi:10.5772/61056

Cited by 7 publications

(6 citation statements)

References 110 publications

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“…Such materials have applications as catalysts in high temperature fuel cells, catalytic convertors, sensors and anticorrosion coatings [194]. Two methods are currently used [30], the anodic oxidation of Ce(III) and the subsequent formation of the oxide in the bulk solution, or the cathodic generation of a base, which then hydrolyses Ce(IV); pH conditions are crucial.…”

Section: Environmental Treatment and Recyclingmentioning

confidence: 99%

Electrochemical redox processes involving soluble cerium species

Arenas

León

Walsh

2016

Electrochimica Acta

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Anodic oxidation of cerous ions and cathodic reduction of ceric ions, in aqueous acidic solutions, play an important role in electrochemical processes at laboratory and industrial scale. Ceric ions, which have been used for oxidation of organic wastes and off-gases in environmental treatment, are a wellestablished oxidant for indirect organic synthesis and specialised cleaning processes, including oxide film removal from tanks and process pipework in nuclear decontamination. They also provide a classical reagent for chemical analysis in the laboratory. The reversible oxidation of cerous ions is an important reaction in the positive compartment of various redox flow batteries during charge and discharge cycling. A knowledge of the thermodynamics and kinetics of the redox reaction is critical to an understanding of the role of cerium redox species in these applications. Suitable choices of electrode material (metal or ceramic; coated or uncoated), geometry/structure (2-or 3-dimensional) and electrolyte flow conditions (hence an acceptable mass transport rate) are critical to achieving effective electrocatalysis, a high performance and a long lifetime. This review considers the electrochemistry of soluble cerium species and their diverse uses in electrochemical technology, especially for redox flow batteries and mediated electrochemical oxidation.

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Section: Environmental Treatment and Recyclingmentioning

confidence: 99%

Electrochemical redox processes involving soluble cerium species

Arenas

León

Walsh

2016

Electrochimica Acta

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“…From the XRD spectrum of PSO, the metal oxide exhibits semicrystalline nature with the characteristic sharp peaks appeared at 2 θ angles of 28.2, 32.8, 47.3, 56.2, 59, and 76.8° were assigned to the (111) (200) (220) (311) (222) and (331) planes, respectively. 36 The broad peak centered at 47.2° in Figure 6(b) designates the amorphous structure of SP-PSO-10 membrane. The XRD spectrum of polymer nanocomposite shows low crystallinity, which proves more disorder structure of the membranes.…”

Section: Resultsmentioning

confidence: 99%

New series of organic–inorganic polymer nanocomposite membranes for fuel cell applications

Sivasubramanian¹,

Hariharasubramanian²,

Deivanayagam

2019

High Performance Polymers

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Flexible organic–inorganic polymer nanocomposite membranes with uniformly distributed metal oxide nanoparticles were prepared using sulfonated poly(ether ether ketone) (SPEEK) as a base material and praseodymium oxide (PSO) as an inorganic additive. The degree of sulfonation of SPEEK was determined by proton nuclear magnetic resonance (NMR) analysis and found to be 60%. The characteristic properties of the polymer nanocomposite membranes were examined by thermogravimetric analysis, X-ray diffraction, ion exchange capacity, water uptake ability, and proton conductivity. The incorporation of metal oxide into the polymer matrix was confirmed by scanning electron microscope with energy dispersive X-ray spectroscopy and X-ray diffraction analyses. The nanocomposite membrane exhibits good thermal stability when compared to that of the pristine membrane and SPEEK with 10 wt% of PSO loading was found to be stable up to 450°C. The assessment of polymer electrolyte membrane is accomplished by fabricating membrane electrode assemblies of pure SPEEK and SP-PSO-10 membranes and the latter produced maximum peak power density of 622 mW cm−2. The constructed SPEEK/PSO nanocomposite membranes offered superior physicochemical properties while applying these materials in an H2-O2 fuel cell.

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“…Such phenomena (surface oxidation under cathodic conditions) are well-known and have been reviewed in the literature. 54 A definite conclusion on this issue, however, will require additional study.…”

Section: ■ Summary and Conclusionmentioning

confidence: 99%

Niobium Carbide and Tantalum Carbide as Nitrogen Reduction Electrocatalysts: Catalytic Activity, Carbophilicity, and the Importance of Intermediate Oxidation States

Alhowity,

Balogun,

Ganesan

et al. 2024

ACS Appl. Mater. Interfaces

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Significant interest in the electrocatalytic reduction of molecular nitrogen to ammonia (the nitrogen reduction reaction: NRR) has focused attention on transition metal carbides as possible electrocatalysts. However, a fundamental understanding of carbide surface structure/NRR reactivity relationships is sparse. Herein, electrochemistry, DFTbased calculations, and in situ photoemission studies demonstrate that NbC, deposited by magnetron sputter deposition, is active for NRR at pH 3.2 but only after immersion of an ambient-induced Nb 2 O 5 surface layer in 0.3 M NaOH, which leaves Nb suboxides with niobium in intermediate formal oxidation states. Photoemission data, however, show that polarization to −1.3 V vs Ag/AgCl restores the Nb 2 O 5 overlayer, correlating with electrochemical measurements showing inhibition of NRR activity under these conditions. In contrast, a similar treatment of a sputter-deposited TaC sample in 0.3 M NaOH fails to reduce the ambient-induced Ta 2 O 5 surface layer, and TaC is inactive for NRR at potentials more positive than −1.0 V even though a significant cathodic current is observed. A TaC sample with surface oxide partially reduced by Ar ion sputtering in UHV prior to in situ transfer to UHV exhibits a restored Ta 2 O 5 surface layer after electrochemical polarization to −1.0 V vs Ag/AgCl. The electrochemical and photoemission results are in accord with DFT-based calculations indicating greater N�N bond activation for N 2 bound end-on to Nb(IV) and Nb(III) sites than for N 2 bound end-on to Nb(V) sites. Thus, theory and experiment demonstrate that with respect to NbC, the formation and stabilization of intermediate (non-d 0 ) oxidation states for surface transition metal ions is critical for N�N bond activation and NRR activity. Additionally, the Nb suboxide surface, formed by immersion in 0.3 M NaOH of ambient-exposed NbC, is shown to undergo reoxidation to catalytically inactive Nb 2 O 5 at −1.3 V vs Ag/AgCl, possibly due to hydrolysis or other, as yet not understood, phenomena.

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Electrochemical Synthesis of Rare Earth Ceramic Oxide Coatings

Cited by 7 publications

References 110 publications

Electrochemical redox processes involving soluble cerium species

Electrochemical redox processes involving soluble cerium species

New series of organic–inorganic polymer nanocomposite membranes for fuel cell applications

Niobium Carbide and Tantalum Carbide as Nitrogen Reduction Electrocatalysts: Catalytic Activity, Carbophilicity, and the Importance of Intermediate Oxidation States

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