Abstract
Regarding dihydrogen as a clean and renewable energy source, ammonia borane (NH3BH3, AB) was considered as a chemical H2-storage and H2-delivery material due to its high storage capacity of dihydrogen (19.6 wt %) and stability at room temperature. To advance the development of efficient and recyclable catalysts for hydrolytic dehydrogenation of AB with parallel insight into the reaction mechanism, herein, ZIF-67-derived fcc-Co@porous carbon nano/microparticles (cZIF-67_nm/cZIF-67_μm) were explored to promote catalytic dehydrogenation of AB and generation of H2(g). According to kinetic and computational studies, zero-order dependence on the concentration of AB, first-order dependence on the concentration of cZIF-67_nm (or cZIF-67_μm), and a kinetic isotope effect value of 2.45 (or 2.64) for H2O/D2O identify the Co-catalyzed cleavage of the H-OH bond, instead of the H-BH2NH3 bond, as the rate-determining step in the hydrolytic dehydrogenation of AB. Despite the absent evolution of H2(g) in the reaction of cZIF-67 and AB in the organic solvents (i.e., THF or CH3OH) or in the reaction of cZIF-67 and water, Co-mediated activation of AB and formation of a Co-H intermediate were evidenced by theoretical calculation, infrared spectroscopy in combination with an isotope-labeling experiment, and reactivity study toward CO2-to-formate/H2O-to-H2 conversion. Moreover, the computational study discovers a synergistic interaction between AB and the water cluster (H2O)9 on fcc-Co, which shifts the splitting of water into an exergonic process and lowers the thermodynamic barrier for the generation and desorption of H2(g) from the Co-H intermediates. With the kinetic and mechanistic study of ZIF-67-derived Co@porous carbon for catalytic hydrolysis of AB, the spatiotemporal control on the generation of H2(g) for the treatment of inflammatory diseases will be further investigated in the near future.
Original language | English |
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Pages (from-to) | 47465-47477 |
Number of pages | 13 |
Journal | ACS Applied Materials and Interfaces |
Volume | 13 |
Issue number | 40 |
DOIs | |
Publication status | Published - 2021 Oct 13 |
Keywords
- ammonia borane
- dehydrogenation
- heterogeneous catalysts
- hydrogen evolution reaction
- metal hydride
- metal-organic framework
ASJC Scopus subject areas
- General Materials Science