Decomposition of water on clean and oxidized aluminum(100)

Paul, Jan; Hoffmann, F. M.

doi:10.1021/j100412a083

Cited by 77 publications

(46 citation statements)

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“…Secondly, cerium has an important influence on the morphology of the products generated in the reaction of Al–Ce composites with water. Aluminum without the dense oxide layer can react with water instantly to generate hydrogen, but the hydrolysis products cover aluminum particles and inhibit hydrogen generation . In the ball milling process, cerium elements are dispersed around the surface of aluminum particles.…”

Section: Resultsmentioning

confidence: 93%

Hydrogen Generation from Highly Activated Al–Ce Composite Materials in Pure Water

Luo

Liu

et al. 2011

J. Am. Ceram. Soc.

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The reaction of aluminum with pure water is an eco‐friendly approach to generate hydrogen. The main difficulty associated with this approach is that an oxide or hydroxide protective film around aluminum particles prohibit the hydrogen generation. In this article, a kind of highly activated Al–Ce composite material has been developed via a convenient ball milling method. Typically, Al–13 wt% Ce has a total hydrogen production of 1134 mL/g and a conversion yield of 92.42% within 60 min. The influences of the cerium concentration and ball milling time on the hydrogen production efficiency are discussed based on XPS, XRD, FESEM, and BET techniques. In addition, the hydrogen production efficiency can be improved by adding alkali chloride (NaCl or KCl) to the Al–Ce composite materials.

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Section: Resultsmentioning

confidence: 93%

Hydrogen Generation from Highly Activated Al–Ce Composite Materials in Pure Water

Luo

Liu

et al. 2011

J. Am. Ceram. Soc.

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“…The Co or Ni contacted with Mg or Al and formed Mg (Al)/Co and Mg (Al)/Ni micro galvanic cells in the salt solution, which further accelerated the rapid corrosion of Mg and Al and enhanced the hydrogen generation. Paul et al reported that hydrogen could generate when water contacted with a clean Al surface . The freshly generated Ni and Co showed the higher activity, which favored the production of hydrogen.…”

Section: Resultsmentioning

confidence: 99%

“…Paul et al reported that hydrogen could generate when water contacted with a clean Al surface. 21 The freshly generated Ni and Co showed the higher activity, which favored the production of hydrogen. It was further proved in Section 2.…”

Section: Methodsmentioning

confidence: 99%

Synergistic effect of the fresh Co, Ni, and anion ions on aluminum or magnesium with water reactions

et al. 2018

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Summary To analyze the effect of Co and Ni on hydrogen generation in water, the reactions of Mg and Al with water in CoCl2 and NiCl2 solutions are studied in terms of amount of H2 produced and rate of reaction. Mg rapidly reacts with water in CoCl2 and NiCl2, producing high amount of H2 without induction time. While there is a short induction time is detected for Al─H2O reaction in CoCl2 and NiCl2. In addition to the galvanic cell behavior of the Mg (Al)/Co (Ni) compounds formed, Co and Ni catalyze the hydrogen production reaction; however, the agglomeration of Co or Ni leads to a noticeable decrease in H2 production. The open‐circuit potential in CoCl2 and NiCl2 solutions after the addition of Mg or Al at ambient temperature shows an obvious change, coinciding with the initiation of the hydrogen generation process. Mg rapidly reacts with water in Co (Ac)2, CoSO4, Ni (Ac)2 and NiSO4 solutions as a consequence of its intrinsic metallic properties and of the formation of Co or Ni. The hydrogen production amount is lower (<200 ml g−1) in Co (NO3)2 and Ni (NO3)2, even after adding NaCl. No reaction occurs when adding Al in CoSO4, Co (Ac)2, Co (NO3)2, NiSO4, Ni (Ac)2, and Ni (NO3)2. The synergistic effect of Co, Ni, and anion ions in water affects the rate of Al or Mg corrosion and hydrogen generation.

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“…Although hydrolysis creates hydroxyl groups, other reactions can eliminate hydroxide ions and regenerate oxide structures. In fact, aluminum hydroxide phases are known to be thermodynamically unstable in contact with metal Al, 20 which is similar to what happens when water encounters a clean Al surface 21 . OH − ions are anionic defects that could be driven to the Al:Al 2 O 3 interface under an internal anodic potential 19 .…”

Section: Physicochemical Mechanismmentioning

confidence: 93%

Physicochemical Mechanism for the Continuous Reaction of γ‐Al₂O₃‐Modified Aluminum Powder with Water

Deng

Ferreira

Tanaka

et al. 2007

Journal of the American Ceramic Society

164

160

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Previous experiments showed that γ‐Al2O3‐modified Al powder could continuously react with water and generate hydrogen at room temperature under atmospheric pressure. In this work, a possible physicochemical mechanism is proposed. It reveals that a passive oxide film on Al particle surfaces is hydrated in water. OH− ions are the main mobile species in the hydrated oxide film. When the hydrated front meets the metal Al surface, OH− ions react with Al and release H2. Because of the limited H‐soluble capacity in small Al particles and the low permeability of the hydrated oxide film toward H+ species, H2 molecules accumulate and form small H2 gas bubbles at the Al:Al2O3 interface. When the reaction equilibrium pressure in H2 bubbles exceeds a critical gas pressure that the hydrated oxide film can sustain, the film on the Al particle surfaces breaks and the reaction of Al with water continues. As the surface oxide layer on modified Al particles has a lower tensile strength, the critical gas pressure in H2 bubbles is lower so that under an ambient condition, the reaction of modified Al particles with water is continuous. The proposed mechanism was further confirmed by a new experiment showing that the as‐received Al powder could continuously react with water at temperatures above 40°C and under low vacuum, because the vacuum makes the critical gas pressure in H2 bubbles decrease as well.

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Decomposition of water on clean and oxidized aluminum(100)

Cited by 77 publications

References 0 publications

Hydrogen Generation from Highly Activated Al–Ce Composite Materials in Pure Water

Hydrogen Generation from Highly Activated Al–Ce Composite Materials in Pure Water

Synergistic effect of the fresh Co, Ni, and anion ions on aluminum or magnesium with water reactions

Physicochemical Mechanism for the Continuous Reaction of γ‐Al₂O₃‐Modified Aluminum Powder with Water

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Decomposition of water on clean and oxidized aluminum(100)

Cited by 77 publications

References 0 publications

Hydrogen Generation from Highly Activated Al–Ce Composite Materials in Pure Water

Hydrogen Generation from Highly Activated Al–Ce Composite Materials in Pure Water

Synergistic effect of the fresh Co, Ni, and anion ions on aluminum or magnesium with water reactions

Physicochemical Mechanism for the Continuous Reaction of γ‐Al2O3‐Modified Aluminum Powder with Water

Contact Info

Product

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Physicochemical Mechanism for the Continuous Reaction of γ‐Al₂O₃‐Modified Aluminum Powder with Water