Preparation and characterization of Ni-M (M: Ru, Rh, Pd) nanoclusters as efficient catalysts for hydrogen evolution from ammonia borane methanolysis

Here, first-time preparation, characterization, and catalytic use of hydroxyapatite-supported nickel-based Ni-M (NiRu@HAP, NiRh@HAP, NiPd@HAP) nanoclusters in hydrogen evolution from methanolysis of ammonia borane is reported. Ni-M nanoclusters have been in-situ formed by reduction of hydroxyapatite-supported corresponding metal ions during methanolysis reaction of ammonia borane. The hydroxyapatite-supported Ni-M nanoclusters are isolated as stable solid materials to be characterized by advanced analytical techniques of ICP-OES, TEM, XPS, and XRD. They are found to be isolable, highly redispersible and reusable nanocatalysts for hydrogen evolution from ammonia borane methanolysis under ambient conditions. Ni20Ru80@HAP, Ni38Rh62@HAP, and Ni20Pd80@HAP nanoclusters have TOF values of 58.9, 120.3, and 25.2 min(-1), respectively, in the methanolysis of ammonia borane at 25 +/- 0.1 degrees C. Their apparent activation energy (E-a) values for the same reaction are calculated to be 65.9, 66.8, and 58.1 kJ/mol, respectively, for Ni20Ru80@HAP, Ni38Rh62@HAP, and Ni20Pd80@HAP nanoclusters. (C) 2020 Elsevier Ltd. All rights reserved.