Strong Electronic Metal–Support Interaction Augments Hydrogen Evolution over hcp-Ni/In₂O₃ with Ultrasound-Assisting Dehydrogenation of Ammonia Borane

Abstract

Rational design of highly efficient catalysts for the dehydrogenation of ammonia borane (AB) to produce hydrogen is still challenging. The size and shape effects of catalysts on the performance have been well documented in the past decades. Nevertheless, there is still much space for study on the crystal structure-dependent catalytic performance. Herein, In 2 O 3 -supported hexagonal-close-packed (hcp) Ni (hcp-Ni/In 2 O 3 ) has been prepared via impregnation of corresponding nanoparticles onto In 2 O 3 . The stronger electronic metal−support interaction in hcp-Ni/In 2 O 3 than in fcc-Ni/In 2 O 3 endows it with high capacity to activate AB molecules. It exhibits excellent hydrogen evolution activity from catalytic dehydrogenation of AB with a rate of 7.5 mol H2 mol −1 Ni min −1 , which is 1.7 times that of the supported fcc sample. The systematic experiments and DFT calculations demonstrate that the hcp catalyst possesses stronger hydrophilicity and lower activation energy for the dissociation of H 2 O than the fcc counterpart. Moreover, the assistance with sonication enhances the process of mass and heat transfer and accelerates the reaction. This work provides a new way for the achievement of efficient metastable catalytic systems and promotes the construction of advanced devices toward various applications.