Platinum Nanoparticle Functionalized CNTs as Nanoscaffolds and Catalysts To Enhance the Dehydrogenation of Ammonia-Borane

Abstract

In this paper, the dehydrogenation properties of ammonia-borane (AB, NH3BH3) modified with platinum nanoparticle functionalized carbon nanotubes (CNTs) (Pt@CNTs) that were prepared through a new “ammonia-deliquescence” method are reported. It has been demonstrated that the synergetic catalysis of CNTs and platinum nanoparticles, and the nanoconfinement of AB incorporated into the CNTs are two crucial factors in enhancing the dehydrogenation of AB. Both CNTs and platinum nanoparticles showed favorable catalytic activities toward the thermolysis of AB, which not only depressed the emission of the poisonous byproduct borazine, but also prevented severe material foaming and expansion during the decomposition. Meanwhile, the nanoconfinement of AB through the “ammonia-deliquescence” method led to enhanced dehydrogenation kinetics, releasing the first equivalent of hydrogen at 70 °C within 5 h, while no hydrogen was released from pristine AB under the same conditions. By the Arrhenius method, the activation energy of the modified AB was calculated to be 106.2 kJ mol−1, which is reduced considerably compared to the activation energy for the pristine AB (137.8 kJ mol−1). These results indicate that the “ammonia-deliquescence” method combined with the utilization of Pt@CNTs as catalyst is an effective approach in modifying the properties of AB with favorable dehydrogenation.