Issue 18, 2021

High hydrogen release catalytic activity by quasi-MOFs prepared via post-synthetic pore engineering

Abstract

The catalytic activity of metal–organic frameworks (MOFs) depends largely on the presence of structural defects. In the present study, cobalt based metal–organic framework TMU-10, [Co6(oba)5(OH)2(H2O)2(DMF)4]n·2DMF has been subjected to controlled thermolysis under air atmosphere at different temperatures in the range of 100–700 °C. This treatment results in the removal of ligands, and generation of structural defects and additional porosity in a controlled manner. The resulting materials, denoted as quasi MOFs according to the literature, were subsequently employed as catalysts for hydrogen release from NaBH4 by hydrolysis. The quasi TMU-10 framework obtained at 300 °C (QT-300) shows the highest turnover frequency of the series with a value of 13 333 mL min−1 g−1 at room temperature in the absence of a base, with an activation energy of 56.8 kJ mol−1. The simultaneous presence of micro- and mesopores in QT-300 with unsaturated Lewis acid sites on cobalt nodes due to the conversion of a fraction of Co(II) centers to Co(III) as well as the presence of tetrahedral Co(II) sites is responsible for this catalytic behavior. The influence of the catalyst dosage and BH4 concentration is in good agreement with the Langmuir–Hinshelwood model in which both reactants must be adsorbed onto the catalyst surface. Further investigation on the hydrolysis of the NaBH4 + D2O system presents a primary kinetic isotope effect indicating that water O–H bond cleavage occurs in the rate determining step.

Graphical abstract: High hydrogen release catalytic activity by quasi-MOFs prepared via post-synthetic pore engineering

Supplementary files

Article information

Article type
Paper
Submitted
28 Apr 2021
Accepted
19 Jul 2021
First published
20 Jul 2021

Sustainable Energy Fuels, 2021,5, 4587-4596

High hydrogen release catalytic activity by quasi-MOFs prepared via post-synthetic pore engineering

M. Bagheri, M. Y. Masoomi, E. Domínguez and H. García, Sustainable Energy Fuels, 2021, 5, 4587 DOI: 10.1039/D1SE00661D

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