Enhanced catalytic activity of the nanostructured Co-W-B film catalysts for hydrogen evolution from the hydrolysis of ammonia borane

Recent Advances and Perspectives on Supported Catalysts for Heterogeneous Hydrogen Production from Ammonia Borane

Ammonia borane (AB), a liquid hydrogen storage material, has attracted increasing attention for hydrogen utilization because of its high hydrogen content. However, the slow kinetics of AB hydrolysis and the indefinite catalytic mechanism remain significant problems for its large-scale practical application. Thus, the development of efficient AB hydrolysis catalysts and the determination of their catalytic mechanisms are significant and urgent. A summary of the preparation process and structural characteristics of various supported catalysts is presented in this paper, including graphite, metal-organic frameworks (MOFs), metal oxides, carbon nitride (CN), molybdenum carbide (MoC), carbon nanotubes (CNTs), boron nitride (h-BN), zeolites, carbon dots (CDs), and metal carbide and nitride (MXene). In addition, the relationship between the electronic structure and catalytic performance is discussed to ascertain the actual active sites in the catalytic process. The mechanism of AB hydrolysis catalysis is systematically discussed, and possible catalytic paths are summarized to provide theoretical considerations for the designing of efficient AB hydrolysis catalysts. Furthermore, three methods for stimulating AB from dehydrogenation by-products and the design of possible hydrogen product-regeneration systems are summarized. Finally, the remaining challenges and future research directions for the effective development of AB catalysts are discussed.

Co3O4–CuCoO2 hybrid nanoplates as a low-cost and highly active catalyst for producing hydrogen from ammonia borane

Co₃O₄–CuCoO₂ hybrid nanoplates are low-cost and highly active catalysts for producing hydrogen from ammonia borane with a turnover frequency (TOF) of 65.0 mol_hydrogen mol_cat.⁻¹ min⁻¹.

Ammonia Borane: An Extensively Studied, Though Not Yet Implemented, Hydrogen Carrier

Ammonia borane H3N−BH3 (AB) was re-discovered, in the 2000s, to play an important role in the developing hydrogen economy, but it has seemingly failed; at best it has lagged behind. The present review aims at analyzing, in the context of more than 300 articles, the reasons why AB gives a sense that it has failed as an anodic fuel, a liquid-state hydrogen carrier and a solid hydrogen carrier. The key issues AB faces and the key challenges ahead it has to address (i.e., those hindering its technological deployment) have been identified and itemized. The reality is that preventable errors have been made. First, some critical issues have been underestimated and thereby understudied, whereas others have been disproportionally considered. Second, the potential of AB has been overestimated, and there has been an undoubted lack of realistic and practical vision of it. Third, the competition in the field is severe, with more promising and cheaper hydrides in front of AB. Fourth, AB has been confined to lab benches, and consequently its technological readiness level has remained low. This is discussed in detail herein.

Highly Dispersed CuNi Nanoparticles Supported on Reduced Graphene Oxide as Efficient Catalysts for Hydrogen Generation from NH3BH3

Highly dispersed CuNi nanoparticles (NPs) immobilized on reduced graphene oxide (RGO) were synthesized via the simple in situ co-reduction of an aqueous solution of Copper(II) sulfate pentahydrate, nickel chloride hexahydrate, and graphene oxide (GO) by the reduction of ammonia borane (AB) at room temperature. The powder XRD, FTIR, EDS, and TEM techniques were used to charaterize the structure, size, and composition of the CuNi/RGO catalysts. The as-prepared CuNi/RGO catalysts showed excellent catalytic performance toward the hydrolysis of AB at room temperature. Compared to Cu/RGO, Ni/RGO, and the RGO-free Cu0.6Ni0.4 counterpart, the as-prepared Cu0.6Ni0.4/RGO catalysts showed much better catalytic activity. Furthermore, kinetic studies showed that the catalytic hydrolysis of AB by Cu0.6Ni0.4/RGO has zero order dependence on the AB concentration, but first order dependence on the catalyst concentration. The turnover frequency (TOF) of Cu0.6Ni0.4/RGO catalyst for the hydrolytic dehydrogenation of AB was determined to be about 20.2 mol H2 (mol Cu0.6Ni0.4/RGO)−1 min−1 at 25 °C. In addition, the activation energy (Ea ) of Cu0.6Ni0.4/RGO was determined to be around 17.7 kJ mol−1, which is one of the lowest activation energy’s of the reported metal-based catalysts.