Magnetic field induced synthesis of amorphous CoB alloy nanowires as a highly active catalyst for hydrogen generation from ammonia borane

V-doped activated Ru/Ti2.5V0.5C2 dual-active center accelerate hydrogen production from ammonia borane

Designing and constructing the active center of Ru-based catalysts is the key to efficient hydrolysis of ammonia borane (NH3BH3, AB) for hydrogen production. Herein, V-doped Ru/Ti2.5V0.5C2 dual-active center catalysts were synthesized, showing excellent catalytic ability for AB hydrolysis. The corresponding turnover frequency value was 1072 min-1 at 298 K, and the hydrolysis rate rB of AB was 235 × 103 mL·min-1·gRu-1. X-ray photoelectron spectroscopy results indicated that the interaction between V-doped Ti3C2 and catalytic metal Ru transfers electrons from Ti to Ru, resulting in electron-rich Ru species. According to density functional theory calculations, the activation energy and reaction dissociation energy of the reactants AB and H2O on V-doped catalysts were lower than those of Ru/Ti3C2, thus optimizing the catalytic kinetics of AB hydrolysis. The modification strategy of V-doped Ti3C2 provides a new pathway for the development of high-performance catalysts for AB hydrolysis.

Highly efficient hydrogen production from hydrolysis of ammonia borane over nanostructured Cu@CuCoOx supported on graphene oxide

Designing highly efficient and cheap nanocatalysts for room-temperature hydrolysis of ammonia borane (AB) is of great significance for their real application in hydrogen (H₂)-based fuel cells. Here, we report a kind of noble metal (NM)-free hybrid nanocatalysts composed of heterostructured Cu@CuCoO_x nanoparticles and a graphene oxide support (denoted as Cu@CuCoO_x@GO) and demonstrate their high catalytic performance toward the hydrolysis of AB. By rationally controlling synthetic parameters, we find that optimum Cu_0.3@Cu_0.7CoO_x@GO achieves a superior catalytic activity with a turnover frequency of 44.6 mol_H2 mol_M^-1 min^-1 in H₂O and 98.2 mol_H2 mol_M^-1 min^-1 in 0.2 M NaOH, better than most of previously reported NM-free nanocatalysts. This catalyst also discloses a very low activation energy (E_a) of 35.4 kJ mol^-1. The studies on catalytic kinetics and isotopic experiments attribute the high activity to synergistically structural and compositional advantages of Cu_0.3@Cu_0.7CoO_x@GO, which kinetically accelerates the oxidative cleavage of OH bond in attacked H₂O (the rate-determining step of the hydrolysis of AB). This study thus provides an opportunity for rational design of cheap NM-free nanocatalysts for H₂ production from chemical H₂-storage materials.

Bracelet-Like Ni0.4Cu0.6O Microstructure Composed of Well-Aligned Nanoplatelets as a Superior Catalyst to the Hydrolysis of Ammonia Borane

The development of novel catalysts with both high catalytic activity and low cost toward the hydrolysis of ammonia borane is an important subject in the field of hydrogen energy. In this communications, Ni_xCu_1−xO microstructures with different morphology have been synthesized and their catalytic activities in AB hydrolysis is studied. It's found that bracelet-like nanoplatelets were obtained at x = 0.4 and exhibit highest catalytic performance with turnover frequency of 33.43 mol_hydrogen min⁻¹molcat-1, which much higher than those of most of CuNi-based catalysts in the literature. Pronounced synergistic effects between CuO and NiO in AB hydrolysis also have been observed. Due to the superior catalytic performance and cheapness, the prepared bracelet-like nanoplatelets Ni_0.4Cu_0.6O catalysts can be a strong catalyst candidate in AB hydrolysis.

Ni0.5Cu0.5Co2O4 Nanocomposites, Morphology, Controlled Synthesis, and Catalytic Performance in the Hydrolysis of Ammonia Borane for Hydrogen Production

The catalytic hydrolysis of ammonia borane (AB) is a promising route to produce hydrogen for mobile hydrogen‒oxygen fuel cells. In this study, we have successfully synthesized a variety of Ni_0.5Cu_0.5Co₂O₄ nanocomposites with different morphology, including nanoplatelets, nanoparticles, and urchin-like microspheres. The catalytic performance of those Ni_0.5Cu_0.5Co₂O₄ composites in AB hydrolysis is investigated. The Ni_0.5Cu_0.5Co₂O₄ nanoplatelets show the best catalytic performance despite having the smallest specific surface area, with a turnover frequency (TOF) of 80.2 mol_hydrogen·min^-1·mol^-1_cat. The results reveal that, in contrast to the Ni_0.5Cu_0.5Co₂O₄ nanoparticles and microspheres, the Ni_0.5Cu_0.5Co₂O₄ nanoplatelets are more readily reduced, leading to the fast formation of active species for AB hydrolysis. These findings provide some insight into the design of high-performance oxide-based catalysts for AB hydrolysis. Considering their low cost and high catalytic activity, Ni_0.5Cu_0.5Co₂O₄ nanoplatelets are a strong candidate catalyst for the production of hydrogen through AB hydrolysis in practical applications.

Hexagonal CuCo₂O₄ Nanoplatelets, a Highly Active Catalyst for the Hydrolysis of Ammonia Borane for Hydrogen Production

Catalytic hydrolysis of ammonia borane (AB) has been considered as an effective and safe method to generate hydrogen. Development of highly active and low-cost catalysts is one of the key tasks for this technology. In this work, hexagonal CuCo₂O₄ nanoplatelets with a thickness of approximately 55 nm were prepared. In AB hydrolysis, those nanoplatelets exhibited ultrahigh catalytic activity with turnover frequency (TOF) of 73.4 molhydrogen min-1 molcat-1. As far as we know, this is one of the highest TOF values ever reported for non-noble metal catalysts. In addition, the effects of viscosity and different alkalis on the hydrolysis were also investigated. It is revealed that high viscosity of the reaction medium will retard the hydrolysis reaction. The presence of NaOH, KOH, and Na₂CO₃ in the reaction solution is favorable for hydrolytic process. In contrast, NH₃·H₂O will slow down the hydrolysis rate of ammonia borane. This work can provide some novel insight into the design of catalysts with both high performance and low cost. Besides, some findings in the present study can also offer us some information about how to improve the hydrolysis rates by optimizing the hydrolysis condition.

Ultrahigh Catalytic Activity of l-Proline-Functionalized Rh Nanoparticles for Methanolysis of Ammonia Borane

The synthesis of ultrafine and well-distributed rhodium nanoparticles (NPs) with high efficiency toward methanolysis of ammonia borane (AB) is crucially important but challenging. A facile approach has been developed for synthesizing ultrafine and uniform Rh NPs deposited on carbon by using the small soluble organic molecule (SOM) of l-proline (PRO) as capping agent (Rh-PRO/C). The enrichment of N,O-coordination sites for the metal precursor by using PRO was found to be the key to the synthesis Rh-PRO/C. The as-prepared Rh-PRO/C showed high catalytic activity for ammonia borane methanolysis with the highest total turnover frequency (TOF) of 1035 mol H 2  (mol_Rh  min)^-1 under basic conditions, which was three times higher than that of the state-of-the-art Rh-based catalysts. The excellent catalytic performance of Rh-PRO/C was ascribed to the well-dispersed Rh NPs and the PRO-functionalized metal surface, which can provide more active sites for the reaction. The merit of size-controlled synthesis combined with metal NP surface modification by SOMs is likely to be beneficial in various catalytic fields.

Base-promoted hydrolytic dehydrogenation of ammonia borane catalyzed by noble-metal-free nanoparticles

Noble-metal-free CuCoMo catalysts exhibited ultra-high catalytic performance toward the hydrolytic dehydrogenation of ammonia borane under the assistance of a base.

Magnetic-field-induced synthesis of magnetic wire-like micro- and nanostructures

A lot of physical and chemical preparation methods of one-dimensional (1D) structures are known today. Most of them use highly advanced technology or quite complex chemical reagents. This results in their high costs and difficulties with their implementation to a large industrial scale. Hence, new, facile and inexpensive approaches are still sought. One alternative to wire-like structure production is based on the chemical reduction reactions combined with an external magnetic field, which acts as an independent synthesis parameter. This approach is commonly called magnetic-field-assisted (MFA) synthesis or magnetic-field-induced (MFI) synthesis. As usual, this manufacturing strategy comprises both drawbacks and advantages, which are introduced in this review. Moreover, this work shows that MFI synthesis depends on several synthesis parameters including the strength of the applied magnetic field, reaction temperature, pH value of the reaction environment, chemical composition of the precursor solution, reaction time, and also the presence of surfactants, complexing agents, nucleating agents, initiators as well as organic solvents. All of them have an impact on the morphology and dimensions of wire-like materials and their chemical, physical and mechanical properties. Finally, the opportunities and challenges associated with the magnetic-assisted fabrication of wire-like structures are widely discussed in this review.

MnCo2O4film composed of nanoplates: synthesis, characterization and its superior catalytic performance in the hydrolytic dehydrogenation of ammonia borane

MnCo₂O₄film composed of nanoplates as an active and reusable catalyst towards the hydrolysis of ammonia borane for hydrogen production.