Efficient catalytic hydrolytic dehydrogenation of ammonia borane over surfactant-free bimetallic nanoparticles immobilized on amine-functionalized carbon nanotubes

A series of surfactant-free bimetallic Au-M (M = Co, Ni) nanoparticles (NPs) immobilized on amine-functionalized carbon nanotubes (CNTs) have been successfully prepared using three synthesis methods and then used as effective catalysts for hydrolytic dehydrogenation of ammonia borane (NH3BH3, AB). Surprisingly, compared to the ex situ and one-pot seeding-growth synthesized Au-Co catalysts, the in situ synthesized Au-Co alloy catalyst exhibited remarkably enhanced activity, featuring turnover frequency (TOP) values of 36.05 and 148.51 mol(H2) mol(cat)(-1) min(-1) at 298 and 328 K, respectively, comparable to the values acquired from the reported highly active Co-based catalysts for hydrolytic dehydrogenation of aqueous AB. The XRD investigations of catalysts after heating at different temperatures in Ar atmosphere showed the different existence state of amorphous Co species of Au-Co NPs. In addition, these catalysts could keep the high activity even after 14 h, indicating that they had high stability/durability. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.