Direct Synthesis of Hydrogen Coinserted Hydrated Sodium and Potassium Molybdenum Bronzes: Their Characterization and Selective Preparation of Purple, Blue, and Red Molybdenum Bronzes

Sotani, Noriyuki; Manago, Tomoyuki; Suzuki, Takashi; Eda, Kazuo

doi:10.1006/jssc.2001.9135

Cited by 7 publications

(7 citation statements)

References 17 publications

(12 reference statements)

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“…Recently, a series of tetragonal tungsten bronzes, Na 1−x H x NbWO 6 have exhibited conductivities of the order of 10 −2 S cm −1 at 90°C [84]. Typically, the addition of Nb to the system is done so as to suppress electronic conduction.…”

Section: Pyrochloresmentioning

confidence: 99%

Review of proton conductors for hydrogen separation

Phair

Badwal

2006

Ionics

220

132

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There is a global push to develop a range of hydrogen technologies for timely adoption of the hydrogen economy. This is critical in view of the depleting oil reserves and looming transport fuel shortage, global warming, and increasing pollution. Molecular hydrogen (H 2 ) can be generated by a number of renewable and fossil-fuel-based resources. However, given the high cost of H 2 generation by renewable energy at this stage, fossil or carbon fuels are likely to meet the short-to medium-term demand for hydrogen. In view of this, effective technologies are required for the separation of H 2 from a gas feed (by-products of coal or bio-mass gasification plants, or gases from fossil fuel partial oxidation or reforming) consisting mainly of H 2 and CO 2 with small quantities of other gases such as CH 4 , CO, H 2 O, and traces of sulphur compounds. Several technologies are under development for hydrogen separation. One such technology is based on ion transport membranes, which conduct protons or both protons and electrons. Although these materials have been considered for other applications, such as gas sensors, fuel cells and water electrolysis, the interest in their use as gas separation membranes has developed only recently. In this paper, various classes of proton-conducting materials have been reviewed with specific emphasis on their potential use as H 2 separation membranes in the industrial processes of coal gasification, natural gas reforming, methanol reforming and the watergas shift (WGS) reaction. Key material requirements for their use in these applications have been discussed.

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Section: Pyrochloresmentioning

confidence: 99%

Review of proton conductors for hydrogen separation

Phair

Badwal

2006

Ionics

220

132

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“…The formation of the blue bronze from the red bronze was suggested to be due to the electrochemical surface structuring that occurred during the reduction under strong electric field applied in neutral aqueous solutions. The yellow color formed at far negative potentials may be attributed to the formation of Mo bronzes of the type KMo 16 O 44 or to the electrochemical structural changes as described above or both. The method described herein is expected to have significant implications in the electrochemical coloring applications of Mo oxide bronzes in various sectors.…”

Section: Resultsmentioning

confidence: 90%

Electrochemical Multi-Coloration of Molybdenum Oxide Bronzes

Lee¹,

Saji²,

Lee³

2013

Bulletin of the Korean Chemical Society

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We report a simple electrochemical approach in fabricating multiple colored molybdenum (Mo) oxide bronzes on the surface of a Mo-quartz electrode. A three step electrochemical batch process consisting of linear sweep voltammetry and anodic oxidation followed by cathodic reduction in neutral K2SO4 electrolyte at different end potentials, viz. −0.62, −0.80 and −1.60 V (vs. Hg/HgSO4) yielded red, blue and yellow colored bronzes. The samples produced were analyzed by XRD, EDS, and SIMS. The color variation was suggested to be associated with the cations intercalation into the oxide formed and the simultaneous structural changes that occurred during the cathodic reduction in neutral aqueous medium.

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“…(iv) Terminal bonds in layered hydrates, such as WO 3 ·nH 2 O or MoO 3 ·nH 2 O. [30][31][32]37] The trapping of two protons close to a terminal oxygen atom in the interlayer space, to yield a coordinated water molecule, results in a long M-O bond with the oxygen atom participating in the water molecule, and a short (terminal) M=O bond in the opposite direction. In our case, the TTB structure does not present such an inter-layer space or terminal oxygen atoms since all MO 6 octahedra are corner-linked in all three directions.…”

Section: The Origin Of Peak Pmentioning

confidence: 99%

Proton and Deuteron Exchange in TTB‐Like Na_1.2Nb_1.2W_0.8O₆: Structural Characterization and Spectroscopic Study

et al. 2007

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Keywords: Materials science / Ion exchange / Electron diffraction / IR spectroscopy / Raman spectroscopy Proton-and deuteron-exchange reactions have been performed on Na 1.2 Nb 1.2 W 0.8 O 6 with the tetragonal tungsten bronze (TTB) structure. Na + /H + and Na + /D + ion exchange occurs when aqueous nitric acid solutions are used as the exchanging agent. Up to two out of the three Na + ions are readily exchanged to yield crystalline powder samples. The ionexchange reaction proceeds topotactically, in other words the basic TTB structure is retained, although X-ray and electron diffraction reveal that the exchange process produces an orthorhombic supercell which possesses a true unit cell based

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Direct Synthesis of Hydrogen Coinserted Hydrated Sodium and Potassium Molybdenum Bronzes: Their Characterization and Selective Preparation of Purple, Blue, and Red Molybdenum Bronzes

Cited by 7 publications

References 17 publications

Review of proton conductors for hydrogen separation

Review of proton conductors for hydrogen separation

Electrochemical Multi-Coloration of Molybdenum Oxide Bronzes

Proton and Deuteron Exchange in TTB‐Like Na_1.2Nb_1.2W_0.8O₆: Structural Characterization and Spectroscopic Study

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Direct Synthesis of Hydrogen Coinserted Hydrated Sodium and Potassium Molybdenum Bronzes: Their Characterization and Selective Preparation of Purple, Blue, and Red Molybdenum Bronzes

Cited by 7 publications

References 17 publications

Review of proton conductors for hydrogen separation

Review of proton conductors for hydrogen separation

Electrochemical Multi-Coloration of Molybdenum Oxide Bronzes

Proton and Deuteron Exchange in TTB‐Like Na1.2Nb1.2W0.8O6: Structural Characterization and Spectroscopic Study

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Proton and Deuteron Exchange in TTB‐Like Na_1.2Nb_1.2W_0.8O₆: Structural Characterization and Spectroscopic Study