Zn-MOF assisted dehydrogenation of ammonia borane: Enhanced kinetics and clean hydrogen generation

We report controllable and enhanced hydrogen release kinetics at reduced temperatures in ammonia borane (AB) catalyzed by Zn-MOF-74. AB is loaded into the unsaturated Zn-metal coordinated one-dimensional hexagonal open nanopores of MOF-74 (ABMOF) via solution infiltration. The ABMOF system provides clean hydrogen by suppressing the release of detrimental volatile byproducts such as ammonia, borazine and diborane. These byproducts prevent the direct use of AB as a hydrogen source for polymer electrolyte membrane fuel cell applications. The H2 release temperature, kinetics, and byproduct generation are dependent on the amount of AB loading. We show that nanoconfinement of AB and its interaction with the active Zn-metal centers in MOF are important in promoting efficient and clean hydrogen generation.

► Faster hydrogen release from AB trapped in nanoporous of MOFs. ► Clean hydrogen release by trapping unwanted B-N complexes in nanoporous of MOF. ► Ammonia borane (AB) impregnation and nanoconfinement in Zn-MOF-74 pores. ► High AB loadings up to 40 wt% in nanopores of MOF is reported. ► AB within the MOF pores release about 9 wt% H2 at temperatures below 100 °C.