Themed collection Hydrogen

This article describes the structure–activity relationship and reaction mechanism of photo-hydrogen-evolving molecular devices made up of Ru(II) sensitizers and Pt(II) molecular catalysts.

This article reviews advances in the metal-free activation of hydrogen and the utilization of these and related systems in catalytic hydrogenations.

Significant advantages result from combining the disparate hydrogen release pathways for ammonia-borane (AB) dehydrogenation using ionic liquids (ILs) and transition metal catalysts. With the RuCl₂(PMe₃)₄ catalyst precursor, AB dehydrogenation selectivity and extent are maximized in an IL with the moderately coordinating ethylsulfate anion.

Mixtures containing ammonia-borane and sec-butylamine-borane remain liquid throughout the hydrogen release process that affords tri(N-sec-butyl)borazine and polyborazylene.

Porous nanotube networks are a novel family of ‘carbon superstructures’ with superior structural characteristics and many potential applications.

Thermal and photochemical reactions relevant to photocatalytic hydrogen production have been investigated on rhodium–gold heterobimetallic constructs.

Transfer hydrogenation of polarized olefins with ammonia borane was achieved at room temperature proceeding stepwise with a unique hydroboration intermediate.

By adding a Ti catalyst to nanosized NaAlH₄ (<20 nm) hydrogen desorption rates are enhanced. Adding the Ti catalyst before the alanate resulted in a superior material.

A cobaloxime catalyst evolves H₂ photocatalytically when attached on dye-sensitised TiO₂.

A synergetic effect of K, Ti and F together on improving the reversible hydrogen storage properties of NaAlH₄ is found by intruding K₂TiF₆ as catalyst precursor.

The hydrogen storage properties of Mg₂(dobdc) are probed by adsorption experiments, infrared spectroscopy, and neutron scattering techniques, demonstrating that the open coordination sites are of benefit for high-density storage."

The solid state dehydrogenation of Mg(BH₄)₂ to Mg(B₃H₈)₂ has been shown to be reversible under the conditions of moderate temperature and pressure that preclude the formation of polyboranes through condensation reactions.

H atom disorder and rapid reorientation of NH₄⁺ and BH₄⁻ ions in hydrogen storage material NH₄BH₄.

Molecular H₂ was activated by S/SH bridged dinuclear Ru/Ge complexes, which model the activation process of the “unready” state of [NiFe] hydrogenase.

Preliminary investigations of proton and electron transfers on new dissymmetrically disubstituted diiron dithiolate species [Fe₂(CO)₄(κ²-P^Ph₂N^Ph₂)(μ-pdt)] have been done.

The addition of H₂ across a transition metal–borane bond is reported for the first time. Successive hydrogen addition to a rhodium–norbornadiene complex leads to the elimination of the organic species and a recharging of the boron–hydrogen bond providing active hydrogenation catalysts.

The crystal structure of the diammoniate of diborane is presented for the first time since its discovery in 1923.

A bis-diphosphine nickel complex with tert-butyl functionalized pendant amines functions as a highly active electrocatalyst for the oxidation of hydrogen in the presence of base.

A bifunctional pyrazolylborane is introduced that is capable of heterolytic dihydrogen activation at ambient temperature and pressure; the resulting zwitterionic dihydro congener represents a potential metal-free hydrogenation catalyst.

Investigations of an observation that the rate of H₂ oxidation by a hydrogenase decreases as the dissolved gas concentration increases.

The enthalpy of formation of MgH₂ is lowered by 11 kJ mol⁻¹ if the hydride particles are smaller than 3 nm.

Multimode hydriding/dehydriding reactions of CaPd proceed via hydrogen solution/dissolution and phase decomposition/recombination over wide temperature ranges.

Self-assembled supramolecular photocatalytic systems produced H₂ in aqueous solutions upon visible light irradiation.

The applicability of different density functional methods to the problem of dihydrogen dissociation in an electric field as a model for FLP activation and the bi-radical character of the reaction are investigated.

The ruthenium hydride of (Ar₄CpOH)Ru(CO)₂H exchanges cleanly and rapidly with D₂ at room temperature to generate the ruthenium deuteride. A chain mechanism is proposed to explain the much more rapid exchange of RuH/D₂ than RuCO exchange with ¹³CO.

MOFs comprised of internally polarized 1,3-azulenedicarboxylate were synthesized. The guest free MOF exhibits strong MOF-H₂ interactions (7.8–6.8 kJ mol⁻¹) revealing the significant impact of internally polarized azulene backbone to stabilized H₂ molecules in the framework.

Hydrogen gas is generated by the electrolysis of liquid ammonia which has high hydrogen capacity of 17.8 mass%.

Novel [Ir(C⁁N)₂(N⁁N)]⁺ complexes with N⁁N ligands containing vinyl groups were synthesized resulting in quintupled turn-over numbers for the photocatalytic hydrogen production compared to analogous non-vinyl compounds.

The LiBH₄/Mg₂NiH₄ hydride system reversibly cycles hydrogen via a new reaction path with exceptionally low enthalpy and entropy.

Bimetallic NiIr alloy nanocatalysts exhibit 100% H₂ selectivity for complete decomposition of hydrous hydrazine at room temperature.

Parahydrogen-induced polarization was observed in the gas phase heterogeneous hydrogenation of propyne catalyzed by Pd⁰ nanoparticles embedded in an ionic liquid phase supported on activated carbon fibers (Pd⁰/SILP/ACF). The essential role of the ionic liquid is demonstrated.

N-Heterocycles are reduced in the presence of a catalytic amount of the borane B(C₆F₅)₃ and H₂.

The mechanism of terminal- to μ-hydride isomerisation in models of synthetic complexes resembling the [FeFe]-hydrogenase active site has been elucidated by DFT calculations.

Building an H-cluster analogue within a poly(pyrrole) modified electrode.

Reversible hydrogen uptake in LiBH₄ is greatly enhanced by a combined effect of nanoconfinement in mesoporous carbon and Ni addition.

A ruthenium(II) complex bearing a chelating N-heterocyclic carbene with an NH₂ group (C–NH₂) is a catalyst for the H₂-hydrogenation of polar bonds in basic solution.