Pressure Strategy To Improve H Atomic Utilization via Optimized Decomposition Pathway in Solid Hydrazine Borane

Hydrazine borane (N2H4BH3, HB), a typical B-N-H compound with very high hydrogen content (15.4 wt %), is regarded as an efficient hydrogen storage material. However, during the pyrolysis at ambient pressure, solid HB decomposes, losing ∼30 wt %, which is rationalized by the evolution of hydrazine (N2H4). Here, high pressure is introduced as an analogous catalyst role that enable to optimize the decomposition pathway of solid HB. This approach improves the H atomic utilization to over 95%. Energy-dispersive spectroscopy (EDS) analysis indicates that pressure inhibits the production of N2H4, in-situ high-pressure-high-temperature Raman and in-situ high-pressure Infrared (IR) spectra, Density functional theory (DFT) calculation, and Hirshfeld analysis reveal that this inhibition is a consequence of pressure-enhanced dihydrogen and BN bonds. The superior hydrogen release properties of HB under high pressure make it a candidate for use in the synthesis of superconductor CeH9 as a hydrogen source.

Efficient and complete dehydrogenation of hydrazine borane over a CoPt catalyst

Bimetallic CoPt alloy nanoparticles (NPs) immobilized on CeO2 nanorods (CoPt/CeO2) were synthesized by a facile wet-chemistry reduction method, which showed the highest catalytic efficiency reported to date for the complete dehydrogenation of hydrazine borane with a high TOF value of up to 5454 h-1 at 323 K.

MIL-101 supported CeOx-modified NiPt nanoparticles as a highly efficient catalyst toward complete dehydrogenation of hydrazine borane

High hydrogen content and excellent stability at room temperature promote hydrazine borane (HB, N2H4BH3) as a promising chemical hydrogen storage material. However, the development of high efficient and selective catalysts...

Complete Dehydrogenation of Hydrazine Borane on Manganese Oxide Nanorod-Supported Ni@Ir Core-Shell Nanoparticles

Hydrazine borane (HB; N₂H₄BH₃) has been considered to be one of the most promising solid chemical hydrogen storage materials owing to its high hydrogen capacity and stability under ambient conditions. Despite that, the high purity of hydrogen production from the complete dehydrogenation of HB stands as a major problem that needs to be solved for the convenient use of HB in on-demand hydrogen production systems. In this study, we describe the development of a new catalytic material comprised of bimetallic Ni@Ir core-shell nanoparticles (NPs) supported on OMS-2-type manganese oxide octahedral molecular sieve nanorods (Ni@Ir/OMS-2), which can reproducibly be prepared by following a synthesis protocol including (i) the oleylamine-mediated preparation of colloidal Ni@Ir NPs and (ii) wet impregnation of these ex situ synthesized Ni@Ir NPs onto the OMS-2 surface. The characterization of Ni@Ir/OMS-2 has been done by using various spectroscopic and visualization techniques, and their results have revealed the formation of well-dispersed Ni@Ir core-shell NPs on the surface of OMS-2. The catalytic employment of Ni@Ir/OMS-2 in the dehydrogenation of HB showed that Ni_0.22@Ir_0.78/OMS-2 exhibited high dehydrogenation selectivity (>99%) at complete conversion with a turnover frequency (TOF) value of 2590 h^-1 at 323 K, which is the highest activity value among all reported catalysts for the complete dehydrogenation of HB. Furthermore, the Ni_0.22@Ir_0.78/OMS-2 catalyst enables facile recovery and high stability against agglomeration and leaching, which make it a reusable catalyst in the complete dehydrogenation of HB. The studies reported herein also include the collection of wealthy kinetic data to determine the activation parameters for Ni_0.22@Ir_0.78/OMS-2-catalyzed dehydrogenation of HB.

Noble-metal-free nanocatalysts for hydrogen generation from boron- and nitrogen-based hydrides

We focus on the recent advances in non-noble metal catalyst design, synthesis and applications in dehydrogenation of chemical hydrides (e.g. NaBH₄, NH₃BH₃, NH₃, N₂H₄, N₂H₄BH₃) due to their high hydrogen contents and CO-free H₂ production.

Modified Nimo Nanoparticles for Efficient Catalytic Hydrogen Generation from Hydrous Hydrazine

Precious metal-free NiMoM (M = Pr2O3, Cu2O) catalysts have been synthesized through a simple coreduction method, without any surfactant or support material, and characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The resultant Pr2O3- or Cu2O-modified NiMo catalysts exhibit different structures, which is due to a difference in the synergistic effects of NiMo and the modifying elements. NiMoPr2O3 has an amorphous structure, with low crystallinity and uniform particle dispersion, while NiMo@Cu2O adopts the core–shell structure, where the core and shell are synergistic with each other to promote electron transfer efficiency. The support material-free nanocatalysts Ni9Mo1(Pr2O3)0.375 and Ni4Mo@Cu2O are both highly efficient compared with bimetallic NiMo catalysts, in terms of hydrogen generation from hydrous hydrazine (N2H4·H2O) at 343 K, with total turnover frequencies (TOFs) of 62 h−1 and 71.4 h−1, respectively. Their corresponding activation energies (Ea) were determined to be 43.24 kJ mol−1 and 46.47 kJ mol−1, respectively. This is the first report on the use of Pr-modified NiMo and core–shell NiMo@Cu2O catalysts, and these results may be used to promote the effective application of noble metal-free nanocatalysts for hydrogen production from hydrous hydrazine.

Bimetallic NiIr nanoparticles supported on lanthanum oxy-carbonate as highly efficient catalysts for hydrogen evolution from hydrazine borane and hydrazine

La₂O₂CO₃-supported NiIr nanoparticles (NPs) have been facilely synthesized via a sodium–hydroxide-assisted reduction approach and used as highly efficient catalysts for hydrogen generation from hydrazine borane and hydrous hydrazine.

Metal–organic framework immobilized RhNi alloy nanoparticles for complete H2 evolution from hydrazine borane and hydrous hydrazine

MOF immobilized RhNi alloy NPs with size of 2.8 nm have been fabricated via a reduction rate controlled method and applied as efficient catalyst for complete H₂ evolution from hydrazine borane and hydrous hydrazine.

Iridium(iii) hydrido complexes for the catalytic dehydrogenation of hydrazine borane

A series of POCOP iridium hydride complexes with differently substituted aryl backbones catalyse the selective release of one equivalent of hydrogen from hydrazine borane.

Ruthenium nanoparticles confined in SBA-15 as highly efficient catalyst for hydrolytic dehydrogenation of ammonia borane and hydrazine borane

Ultrafine ruthenium nanoparticles (NPs) within the mesopores of the SBA-15 have been successfully prepared by using a “double solvents” method, in which n-hexane is used as a hydrophobic solvent and RuCl₃ aqueous solution is used as a hydrophilic solvent. After the impregnation and reduction processes, the samples were characterized by XRD, TEM, EDX, XPS, N₂ adsorption-desorption, and ICP techniques. The TEM images show that small sized Ru NPs with an average size of 3.0 ± 0.8 nm are uniformly dispersed in the mesopores of SBA-15. The as-synthesized Ru@SBA-15 nanocomposites (NCs) display exceptional catalytic activity for hydrogen generation by the hydrolysis of ammonia borane (NH₃BH₃, AB) and hydrazine borane (N₂H₄BH₃, HB) at room temperature with the turnover frequency (TOF) value of 316 and 706 mol H₂ (mol Ru min)⁻¹, respectively, relatively high values reported so far for the same reaction. The activation energies (E_a) for the hydrolysis of AB and HB catalyzed by Ru@SBA-15 NCs are measured to be 34.8 ± 2 and 41.3 ± 2 kJ mol⁻¹, respectively. Moreover, Ru@SBA-15 NCs also show satisfied durable stability for the hydrolytic dehydrogenation of AB and HB, respectively.

Non-noble bimetallic CuCo nanoparticles encapsulated in the pores of metal–organic frameworks: synergetic catalysis in the hydrolysis of ammonia borane for hydrogen generation

Non-noble bimetallic CuCo alloy nanoparticles were successfully encapsulated in the pores of MIL-101 without aggregation on the external surfaces of the host framework, which exhibit excellent catalytic activity for hydrolytic dehydrogenation of ammonia borane.

One-pot synthesis of core-shell Cu@SiO2 nanospheres and their catalysis for hydrolytic dehydrogenation of ammonia borane and hydrazine borane

Ultrafine copper nanoparticles (Cu NPs) within porous silica nanospheres (Cu@SiO₂) were prepared via a simple one-pot synthetic route in a reverse micelle system and characterized by SEM, TEM, EDX, XRD, N₂ adsorption-desorption, CO-TPD, XPS, and ICP methods. The characterized results show that ultrafine Cu NPs with diameter of around 2 nm are effectively embedded in the center of well-proportioned spherical SiO₂ NPs of about 25 nm in diameter. Compared to commercial SiO₂ supported Cu NPs, SiO₂ nanospheres supported Cu NPs, and free Cu NPs, the synthesized core-shell nanospheres Cu@SiO₂ exhibit a superior catalytic activity for the hydrolytic dehydrogenation of ammonia borane (AB, NH₃BH₃) and hydrazine borane (HB, N₂H₄BH₃) under ambient atmosphere at room temperature. The turnover frequencies (TOF) for the hydrolysis of AB and HB in the presence of Cu@SiO₂ nanospheres were measured to be 3.24 and 7.58 mol H₂ (mol Cu min)⁻¹, respectively, relatively high values for Cu nanocatalysts in the same reaction. In addition, the recycle tests show that the Cu@SiO₂ nanospheres are still highly active in the hydrolysis of AB and HB, preserving 90 and 85% of their initial catalytic activity even after ten recycles, respectively.