Evenly dispersed microspherical amorphous alloy CoxB1-x: Robust and magnetically recyclable catalyst for alcoholyzing ammonia borane to release H2

By properly adjusting mole ratio of Co2+/BH4-, a series of CoxB1-x (x = 0.25, 0.50, 0.75) amorphous alloys were synthesized via an one-step mild liquid reduction route with assistance of suitable shape modifier and dispersant The characterization results of morphology, phase composition and magnetism by virtue of various analytical techniques demonstrate that under the given conditions the as-fabricated CoxB1-x products all belong to the typical amorphous alloys with a level of ferromagnetism, mostly taking the shape of nearly monodispersed microspheres with size distribution of 200-300 nm; the grain size gets smaller with rise of Co content. The catalytic ability evaluations of the CoxB1-x samples via alcoholyzing ammonia borane for liberating H-2 gas confirm that the Co0.75B0.25 sample holds the highest catalytic activity, enabling to fully release H-2 in 40 min at 298 K with the apparent activation energy of 38.93 kJ/mol, which can still remain 71% initial catalytic activity after 5 recycles. In theory, the special microsphere constructing strategy could be also extended to other metal-nonmetal systems for fabricating highly active amorphous alloy catalysts. (C) 2017 Elsevier B.V. All rights reserved.