Porous MnO2 hollow cubes as new nanoscaffold materials for the dehydrogenation promotion of ammonia-borane (AB)

We report on the synthesis of porous MnO2 hollow cubes via a microemulsion method and their application as new nanoscaffold materials to confine ammonia borane (AB) for enhancing the dehydrogenation process. Different loading levels of AB loaded in MnO2 are investigated. The results show that porous MnO2 hollow cubes have a high surface area of 297.9 m(2)/g and AB is uniformly loaded in the porous MnO2. It is also found that in the examined system, MnO2/AB with the mass ratio of 3:1 (3MnO(2)/AB) displays the best dehydrogenation properties. The onset temperature of the dehydrogenation of 3MnO(2)/AB sample is as low as 60 degrees C with the peak temperature at 97 degrees C, while the byproducts such as borazine, diborane and NH3 are completely suppressed. Furthermore, 3MnO(2)/AB sample can release about 0.9 equivalent H-2 within 90 min at 85 degrees C. This study indicates that AB loaded in porous MnO2 is an effective approach in modifying the properties of AB with favorable dehydrogenation. (C) 2012 Elsevier Inc. All rights reserved.