Facilitated hydrogen release kinetics from amine borane functionalization on gate-opening metal-organic framework

Abstract

For the first time, we functionalized the gate-opening metal-organic framework (GO-MOF) of MIL-53(Al) with ammonia borane (AB, NH3BH3) via post-synthesis method. In this report, unusual structural breathing and dehydrogenation behaviors of AB doped MOF (MIL-53-AB) were discovered. Surface coating triggered the GO-MOF breathing phenomenon and opened the structure, and gate was closed after dehydrogenation. The dehydrogenation peak temperature was greatly reduced by 30 degrees C compared to that of pristine AB with suppressed byproduct like ammonia. The MOFs with surface coated AB exhibited remarkably fast hydrogen generation rate and corresponding low apparent activation energy, estimated at < 40 kJ/mol, which is much lower than that of crystalline AB, and even comparable to AB hydrolysis with catalysts. The ammonia borane functionalized MIL-53 has shown greatly improved dehydrogenation from solid phase of AB.