Auf zur Wasserstoffentwicklung: Das Infrarot‐Spektrum von hydratisiertem Aluminiumhydrid‐Hydroxid HAlOH+(H2O)n−1, n=9–14

Heller, Jakob; Tang, Wai Kit; Cunningham, Ethan M.; Demissie, Ephrem G.; Linde, Christian van der; Lam, Wing Ka; Ončák, Milan; Siu, Chi‐Kit; Beyer, Martin K.

doi:10.1002/ange.202105166

Cited by 2 publications

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“…In the case of Al + (H 2 O) n , H/D exchange experiments with D 2 O indicate that larger clusters are indeed present as HAlOH + (H 2 O) n-1 , but for n > 40, the exchange ceases, [16] leaving the question open whether these clusters resume the Al + (H 2 O) n structure or the H/D exchange reaction, which requires efficient proton transfer, [17] becomes hindered. Our recent infrared spectroscopic study confirmed the presence of the HAlOH + (H 2 O) n-1 structure for n = 9-14, [18] corroborating the theoretically predicted mechanism of H 2 formation in these species. [19,20] Around n = 8, the HAlOH + (H 2 O) n-1 structure is formed.…”

Section: Introductionsupporting

confidence: 86%

“…It is well established that Al + (H 2 O) n rearranges to HAlOH + (H 2 O) n-1 , and we observe the AlÀ H stretching mode in our infrared spectra in traces for n = 4, with quickly increasing intensity for larger clusters. [18] The inserted structure HAlOH + (H 2 O) n-1 does not absorb UV light with λ � 225 nm for n = 2-4, and hydration does not seem to lead to an appreciable redshift. We therefore assign the size-dependence of the absorption cross-section and the disappearance of the absorption to the presence of the HAlOH + (H 2 O) n-1 structure.…”

Section: Photodissociation Of Al + (H 2 O) N N >mentioning

confidence: 99%

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Photochemical Hydrogen Evolution at Metal Centers Probed with Hydrated Aluminium Cations, Al⁺(H₂O)_n, n=1–10

Heller

Pascher

Linde

et al. 2021

Chemistry A European J

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Hydrated aluminium cations have been investigated as a photochemical model system with up to ten water molecules by UV action spectroscopy in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Intense photodissociation was observed starting at 4.5 eV for two to eight water molecules with loss of atomic hydrogen, molecular hydrogen and water molecules. Quantum chemical calculations for n = 2 reveal that solvation shifts the intense 3s-3p excitations of Al + into the investigated photon energy range below 5.5 eV. During the photochemical relaxation, internal conversion from S 1 to T 2 takes place, and photochemical hydrogen formation starts on the T 2 surface, which passes through a conical intersection, changing to T 1 . On this triplet surface, the electron that was excited to the Al 3p orbital is transferred to a coordinated water molecule, which dissociates into a hydroxide ion and a hydrogen atom. If the system remains in the triplet state, this hydrogen radical is lost directly. If the system returns to singlet multiplicity, the reaction may be reversed, with recombination with the hydroxide moiety and electron transfer back to aluminium, resulting in water evaporation. Alternatively, the hydrogen radical can attack the intact water molecule, forming molecular hydrogen and aluminium dihydroxide. Photodissociation is observed for up to n = 8. Clusters with n = 9 or 10 occur exclusively as HAlOH + (H 2 O) n-1 and are transparent in the investigated energy range. For n = 4-8, a mixture of Al + (H 2 O) n and HAlOH + (H 2 O) n-1 is present in the experiment.

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Section: Introductionsupporting

confidence: 86%

Section: Photodissociation Of Al + (H 2 O) N N >mentioning

confidence: 99%

Photochemical Hydrogen Evolution at Metal Centers Probed with Hydrated Aluminium Cations, Al⁺(H₂O)_n, n=1–10

Heller

Pascher

Linde

et al. 2021

Chemistry A European J

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Thermally Activated vs. Photochemical Hydrogen Evolution Reactions–A Tale of Three Metals

Ončák

Siu

Linde

et al. 2023

Chemistry A European J

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Molecular processes behind hydrogen evolution reactions can be quite complex. In macroscopic electrochemical cells, it is extremely difficult to elucidate and understand their mechanism. Gas phase models, consisting of a metal ion and a small number of water molecules, provide unique opportunities to understand the reaction pathways in great detail. Hydrogen evolution in clusters consisting of a singly charged metal ion and one to on the order of 50 water molecules has been studied extensively for magnesium, aluminum and vanadium. Such clusters with around 10-20 water molecules are known to eliminate atomic or molecular hydrogen upon mild activation by room temperature blackbody radiation. Irradiation with ultraviolet light, by contrast, enables hydrogen evolution already with a single water molecule. Here, we analyze and compare the reaction mechanisms for hydrogen evolution on the ground state as well as excited state potential energy surfaces. Five distinct mechanisms for evolution of atomic or molecular hydrogen are identified and characterized.

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Auf zur Wasserstoffentwicklung: Das Infrarot‐Spektrum von hydratisiertem Aluminiumhydrid‐Hydroxid HAlOH⁺(H₂O)_n−1, n=9–14

Abstract: Diese Autoren haben zu gleichen Teilen zu der Arbeit beigetragen.Hintergrundinformationen und Identifikationsnummern (ORCIDs) der Autoren sind unter:

Cited by 2 publications

References 50 publications

Photochemical Hydrogen Evolution at Metal Centers Probed with Hydrated Aluminium Cations, Al⁺(H₂O)_n, n=1–10

Photochemical Hydrogen Evolution at Metal Centers Probed with Hydrated Aluminium Cations, Al⁺(H₂O)_n, n=1–10

Thermally Activated vs. Photochemical Hydrogen Evolution Reactions–A Tale of Three Metals

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Auf zur Wasserstoffentwicklung: Das Infrarot‐Spektrum von hydratisiertem Aluminiumhydrid‐Hydroxid HAlOH+(H2O)n−1, n=9–14

Abstract: Diese Autoren haben zu gleichen Teilen zu der Arbeit beigetragen.Hintergrundinformationen und Identifikationsnummern (ORCIDs) der Autoren sind unter:

Cited by 2 publications

References 50 publications

Photochemical Hydrogen Evolution at Metal Centers Probed with Hydrated Aluminium Cations, Al+(H2O)n, n=1–10

Photochemical Hydrogen Evolution at Metal Centers Probed with Hydrated Aluminium Cations, Al+(H2O)n, n=1–10

Thermally Activated vs. Photochemical Hydrogen Evolution Reactions–A Tale of Three Metals

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Auf zur Wasserstoffentwicklung: Das Infrarot‐Spektrum von hydratisiertem Aluminiumhydrid‐Hydroxid HAlOH⁺(H₂O)_n−1, n=9–14

Photochemical Hydrogen Evolution at Metal Centers Probed with Hydrated Aluminium Cations, Al⁺(H₂O)_n, n=1–10

Photochemical Hydrogen Evolution at Metal Centers Probed with Hydrated Aluminium Cations, Al⁺(H₂O)_n, n=1–10