Reversible isothermal sorption of hydrogen by tungsten trioxide in presence of platinum

Berzins, A. R.; Sermon, Paul A.

doi:10.1038/303506a0

Cited by 17 publications

(25 citation statements)

References 28 publications

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“…The amount of W 5+ purely from hydrogenation may then be the difference between the two dashed fitting curves, neglecting a mutual enhancement of the two effects. The hydrogen content in H x WO 3 has been shown to be proportional to the square root of the applied hydrogen pressure [18,44]. With this relation, the amount of W 5+ is proportional to √ p H 2 and thus to the amount of hydrogen x in H x WO 3−δ .…”

Section: Resultsmentioning

confidence: 96%

“…Electrochemical hydrogen insertion is relatively facile, but the electrochemical surface changes due to the aqueous environment hinder photoemission measurements. Gaseous hydrogen intercalation into WO 3 does not change the surface but is feasible only at UHV-incompatible pressures and in the presence of dissociatively active sites [18], limiting photoemission experiments to the study of postmortem samples.…”

Section: Introductionmentioning

confidence: 99%

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Hydrogen in tungsten trioxide by membrane photoemission and density functional theory modeling

et al. 2021

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The measurement of hydrogen-induced changes in the electronic structure of transition metal oxides by x-ray photoelectron spectroscopy is a challenging endeavor, since no photoelectron can be unambiguously assigned to hydrogen. The H-induced electronic structure changes in tungsten trioxide have been known for more than 100 years but are still controversially debated. The controversy stems from the difficulty in disentangling effects due to hydrogenation from the effects of oxygen deficiencies. Using a membrane approach to x-ray photoelectron spectroscopy, in combination with tunable synchrotron radiation, we measure simultaneously core levels and the valence band up to a hydrogen pressure of 1000 mbar. Upon hydrogenation, the intensities of the W 5+ core level and a state close to the Fermi level increase following the pressure-composition isotherm curve of bulk H x WO 3 . Combining experimental data and density functional theory, the description of the hydrogen-induced coloration by a proton polaron model is corroborated. Although hydrogen is the origin of the electronic structure changes near the Fermi edge, the valence band edge is now dominated by tungsten orbitals instead of oxygen as is the case for the pristine oxide, having wider implications for its use as a (photoelectrochemical) catalyst.

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Section: Resultsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Hydrogen in tungsten trioxide by membrane photoemission and density functional theory modeling

et al. 2021

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“…The effect is particularily strong in WO 3 78 and MoO 3 910, which have long been known for their gasochromic properties, and can be utilized as hydrogen10 and ammonia sensors11. Hydrogen atoms from molecular hydrogen or decomposition of hydrogen containing reducing molecules such as ammonia intercalate into the oxide and form hydrogen molybdenum bronzes H x Mo x 5+ Mo 1−x 6+ O 3 10.…”

mentioning

confidence: 99%

Hydrogen reduction of molybdenum oxide at room temperature

Borgschulte

Sambalova

Delmelle

et al. 2017

Sci Rep

162

156

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The color changes in chemo- and photochromic MoO3 used in sensors and in organic photovoltaic (OPV) cells can be traced back to intercalated hydrogen atoms stemming either from gaseous hydrogen dissociated at catalytic surfaces or from photocatalytically split water. In applications, the reversibility of the process is of utmost importance, and deterioration of the layer functionality due to side reactions is a critical challenge. Using the membrane approach for high-pressure XPS, we are able to follow the hydrogen reduction of MoO3 thin films using atomic hydrogen in a water free environment. Hydrogen intercalates into MoO3 forming HxMoO3, which slowly decomposes into MoO2 +1/2 H2O as evidenced by the fast reduction of Mo6+ into Mo5+ states and slow but simultaneous formation of Mo4+ states. We measure the decrease in oxygen/metal ratio in the thin film explaining the limited reversibility of hydrogen sensors based on transition metal oxides. The results also enlighten the recent debate on the mechanism of the high temperature hydrogen reduction of bulk molybdenum oxide. The specific mechanism is a result of the balance between the reduction by hydrogen and water formation, desorption of water as well as nucleation and growth of new phases.

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“…They are meaningful for understanding hydrogen incorporated into metal oxides at high temperatures. However, metal oxide semiconductors usually interact with hydrogen at lower or even room temperature in their hydrogen-related applications, such as hydrogenation catalysis6, hydrogen storage78, and low-temperature hydrogen sensing9. It is well known that the interaction between metal oxides and hydrogen strongly depends on the reaction temperature.…”

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confidence: 99%

Highly mobile and reactive state of hydrogen in metal oxide semiconductors at room temperature

Chen

Wang

et al. 2013

Sci Rep

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Hydrogen in metal oxides usually strongly associates with a neighboring oxygen ion through an O-H bond and thus displays a high stability. Here we report a novel state of hydrogen with unusually high mobility and reactivity in metal oxides at room temperature. We show that freshly doped hydrogen in Nb2O5 and WO3 polycrystals via electrochemical hydrogenation can reduce Cu2+ ions into Cu0 if the polycrystals are immersed in a CuSO4 solution, while this would not happen if the hydrogenated polycrystals have been placed in air for several hours before the immersion. Time-dependent studies of electrochemically hydrogenated rutile single crystals reveal two distinct states of hydrogen: one as protons covalently bonded to oxygen ions, while the other one is highly unstable with a lifetime of just a few hours. Observation of this mobile and reactive state of hydrogen will provide new insight into numerous moderate and low temperature interactions between metal oxides and hydrogen.

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Reversible isothermal sorption of hydrogen by tungsten trioxide in presence of platinum

Cited by 17 publications

References 28 publications

Hydrogen in tungsten trioxide by membrane photoemission and density functional theory modeling

Hydrogen in tungsten trioxide by membrane photoemission and density functional theory modeling

Hydrogen reduction of molybdenum oxide at room temperature

Highly mobile and reactive state of hydrogen in metal oxide semiconductors at room temperature

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