Recent Advances in Applications of Co-B Catalysts in NaBH4-Based Portable Hydrogen Generators

This review highlights the opportunities of catalytic hydrolysis of NaBH4 with the use of inexpensive and active Co-B catalysts among the other systems of hydrogen storage and generation based on water reactive materials. This process is important for the creation of H2 generators required for the operation of portable compact power devices based on low-temperature proton exchange membrane fuel cells (LT PEM FC). Special attention is paid to the influence of the reaction medium on the formation of active state of Co-B catalysts and the problem of their deactivation in NaBH4 solution stabilized by alkali. The novelty of this review consists in the discussion of basic designs of hydrogen generators based on NaBH4 hydrolysis using cobalt catalysts and the challenges of their integration with LT PEM FC. The potential of using batch reactors in which there is no need to use aggressive alkaline NaBH4 solutions is discussed. Solid-phase compositions or pellets based on NaBH4 and cobalt-containing catalytic additives are proposed, the hydrogen generation from which starts immediately after the addition of water. The review made it possible to formulate the most acute problems, which require new sci-tech solutions.

Design strategies of highly selective nickel catalysts for H2 production via hydrous hydrazine decomposition: a review

Hydrazine, a widely used liquid propellant, has the potential to be employed as a hydrogen source in certain instances and has therefore attracted considerable attention; consequently, the complete decomposition of hydrazine with 100% H2 selectivity under mild conditions has become the current research focus for catalyst design. In this review, the strategies for the design of efficient catalysts are summarized for complete hydrazine decomposition. The first part of this review introduces the mechanism of hydrazine decomposition, while the second part illustrates the key factors influencing the H2 selectivity of nickel catalysts, including the effects of alloying, alkali promoter addition and strong metal–support interactions. Finally, the critical elements of catalyst design employed in industrial applications are analyzed.

In-liquid plasma: a novel tool in the fabrication of nanomaterials and in the treatment of wastewaters

Attempts to generate plasma in liquids have been successful and various devices have been proposed.

Mesoporous Face-Centered-Cubic In4Ni Alloy Nanorices: Superior Catalysts for Hydrazine Dehydrogenation in Aqueous Solution

Mesoporous face-centered-cubic (fcc) In4Ni alloy nanorices (NRs) were successfully synthesized as superior catalysts for N2H4 dehydrogenation in aqueous solution via a facile solution plasma technique (SPT) in an ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]). This incorporation introduces basic sites for dehydrogenation. Also, the synthesis of In and Ni weakens the interactions among generated adspecies such as H2 and NHx and surface metal atoms. Alongside their unique NR structure, the as-prepared fcc-In4Ni alloy NRs exhibited superior performance for N2H4 dehydrogenation in aqueous solution. The activation energy of the fcc-In4Ni alloy NRs was 38.9 ± 1.0 kJ mol(-1). The NRs were also found to be stable for catalytic N2H4 dehydrogenation in aqueous solution, providing an average TOF value of 82.0 (mol of H2 (mol of active In4Ni min)(-1)) over 30 h reaction. These fcc-In4Ni alloy NRs have demonstrated exceptional performance, which indicates that the construction of hydrogen-producing systems from N2H4, capable of matching the performance of NaBH4 and NH3BH3 hydrogen-producing systems for fuel-cell applications, is a promising possibility.

Solid-state-reaction synthesis of cotton-like CoB alloy at room temperature as a catalyst for hydrogen generation

A novel room-temperature solid-state reaction is developed to synthesize cotton-like CoB alloy (CoBSSR) catalysts with a large specific surface area of 222.4m(2)g(-1). In the hydrolysis of ammonia borane catalyzed by the CoBSSR, the rate of hydrogen generation can reach 68.7mLmin(-1) with a turnover frequency (TOF) value of ca. 6.9Lhydrogenmin(-1)gcatalyst(-1) at 25°C. The TOF value is about 2 times as large as that of CoB alloy prepared by a regular solid-state reaction, which is also much higher than those of the CoB catalysts recently reported in the literature. The activation energy of the hydrolysis of ammonia borane catalyzed by the CoBSSR is as low as 22.78kJmol(-1), hinting that the CoBSSR possesses high catalytic activity, which may be attributed to the large specific surface area and the abundant porous structure. The high catalytic performance, good recoverability and low cost of the CoBSSR enable it to be a promissing catalyst condidate in the hydrolysis of ammonia borane for hydrogen production in commercial application.

Synthesis of octahedral, truncated octahedral, and cubic Rh2Ni nanocrystals and their structure-activity relationship for the decomposition of hydrazine in aqueous solution to hydrogen

We developed a co-reduction method to synthesize octahedral, truncated octahedral, and cubic Rh2Ni nanocrystals. The shape/size distribution, structural characteristics, and composition of the Rh2Ni nanocrystals are investigated, and their possible formation mechanism at high temperatures in margaric acid/1-aminoheptadecane solution in the presence of tetraethylgermanium and borane trimethylamine complexes is proposed. A preliminary probing of the structure-activity dependence of the surface "clean" Rh2Ni nanocrystals supported on carbon towards hydrazine (N2H4) in aqueous solution dehydrogenation revealed that the higher the percentage of {111} facets, the higher is the activity and H2 selectivity of the nanocrystals. This result was attributed to the {111} facets not only introducing more basic sites, but also weakening the interaction between the produced adspecies (including H2 and NHx) and surface metal atoms in comparison with those of {100} facets. Furthermore, the as-prepared Rh2Ni nanooctahedra exhibited 100% H2 selectivity and high activity at room temperature for H2 generation via N2H4 decomposition. The activation energy of the Rh2Ni nanooctahedra was 41.6 ± 1.2 kJ mol(-1). The Rh2Ni nanooctahedra were stable catalysts for the hydrolytic dehydrogenation of N2H4, providing 27 723 total turnovers in 30 h. Our work provides a new perspective concerning the possibility of constructing hydrogen-producing systems based on N2H4 and surface "clean" Rh2Ni nanocrystal catalysts with defined shapes supported on carbon that possess a competitive performance in comparison with NaBH4 and NH3BH3 hydrogen-producing systems for fuel cell applications.

Synthesis and property of a Helwingia-structured nickel nitride/ nickel hydroxide nanocatalyst in hydrazine decomposition

Helwingia-structured nickel nitride nanoparticles on nickel hydroxide nanosheets exhibited both good activity and excellent stability in aqueous phase hydrazine decomposition.

Highly active and reusable silica-aerogel-supported platinum–cobalt bimetallic catalysts for the dehydrogenation of ammonia borane

In this study, platinum–cobalt bimetallic catalysts supported on mesoporous silica aerogel (SAG), abbreviated as PCx/SAG,x= 1–6, were prepared by facile chemical reduction and a simple, efficient microwave-assisted method using Co and Pt precursors.

Significant effect of base on the improvement of selectivity in the hydrogenation of benzoic acid over NiZrB amorphous alloy supported on γ-Al2O3

The selectivity for cyclohexanecarboxylic acid was significantly enhanced by adding small amounts of bases in benzoic acid hydrogenation.

Retracted Article: Monodisperse CuB23 nanoparticles grown on graphene as highly efficient catalysts for unactivated alkyl halide Heck coupling and levulinic acid hydrogenation

Monodisperse CuB₂₃ nanoparticles grown on graphene exert exceedingly high activity towards unactivated alkyl halide Heck coupling and levulinic acid hydrogenation.

Monodisperse amorphous CuB23 alloy short nanotubes: novel efficient catalysts for Heck coupling of inactivated alkyl halides and alkenes

CuB₂₃ short nanotubes are efficient catalysts to replace Pd and Ni for Heck-type coupling of inactivated alkyl halides and alkenes.