Zeolitic imidazolate frameworks (ZIF‐8, ZIF‐67, and ZIF‐L) for hydrogen production
Hani Nasser Abdelhamid
Abstract
Hydride materials have good performance for hydrogen (H 2 ) gas storage and release. The release of H 2 gas from hydrides via the hydrolysis process can be improved or controlled using a catalyst. Herein, benzoic acid (BA) and hexamethylenetetramine (HMTA) modulate the synthesis of hierarchical porous zeolitic imidazolate framework‐8 (HFZIF‐8, Zn‐based metal organic frameworks [MOFs]), ZIF‐67 (Co‐based MOFs), and leaf‐like ZIF (ZIF‐L). The mechanistic study for the synthesis procedure of ZIF‐8 revealed an in situ synthesis of zinc hydroxide nitrate nanosheets (100‐ to 150‐nm thickness) with an interplanar distance of 0.97 nm between the layers of zinc hydroxide, Zn 5 (OH) 8 2+ . X‐ray diffraction (XRD) data indicated that benzoate ions replaced nitrate ions (2NO 3 − ) between Zn 5 (OH) 8 2+ layers leading to an increase in the interplanar distance (from 0.97 nm to 1.9 nm). Zinc hydroxide benzoate nanosheets showed a fast conversion into HPZIF‐8 at room temperature. The concentration of BA and HMTA tuned the porosity of HPZIF‐8, offering a hierarchical micropore–mesopore structure. The prepared materials increased the hydrolysis rate of sodium borohydride. ZIF‐8 and ZIF‐67 prepared using BA showed high catalytic performance in terms of efficiency and reaction time compared with other materials. The result's findings open new avenues for the synthesis of adequate materials for hydrogen generation via the hydrolysis of hydrides.