ISOBAM-104-stabilized Ni2+ colloidal catalysts were synthesized through a facile method and used for hydrogen generation from hydrolysis of potassium borohydride (KBH4). Ni nanoparticles (NPs) were formed as the active phase during the catalytic process. Ultraviolet–visible spectrophotometry (UV–vis) and transmission electron microscopy were employed to characterize the structure and particle size of the as-formed Ni NPs. The results suggested that the catalytic activity of Ni2+ colloidal catalyst increased with the decreased size of as-formed Ni NPs, which is consistent with the results of density functional theory calculation. The highest catalytic activity of the catalyst can be 12400 ml-H2 min−1 g-Ni−1, which was even higher than that of noble Pt or Pd colloidal catalysts prepared using identical methods and catalytic conditions. According to the Arrhenius method, the ISOBAM-104-stabilized Ni2+ colloidal catalysts showed low activation energies of about 41.3 kJ mol−1 for the hydrogen generation from hydrolysis basic KBH4 solution.
ISOBAM-104 protected Rh/Ag bimetallic nanoparticles (NPs) with average diameter less than 3.0 nm were synthesized by a co-reduction method. Ultraviolet–visible spectroscopy, transmission electron microscopy (TEM), high-resolution TEM and x-ray photoelectron spectroscopy (XPS) were employed to characterize the structure, particle size, and electronic structure of the prepared bimetallic NPs. The catalytic activities of prepared bimetallic NPs for hydrogen generation from hydrolysis of a basic KBH4 solution were evaluated in detail. The results indicated that as-prepared Rh/Ag bimetallic NPs showed a higher catalytic activity than corresponding monometallic NPs. Among all the monometallic NPs and bimetallic NPs, Rh80Ag20 bimetallic NPs exhibited the highest catalytic activity with a value of 6010 mol-H2·h−1·mol-catalyst−1 at pH = 12 and 303 K. The high catalytic activities of Rh/Ag bimetallic NPs could be attributed to presence of negatively charged Rh atoms and positively charged Ag atoms, which is supported by the results of XPS and density functional theory calculation. Based on the kinetic study, the apparent activation energy for the hydrolysis reaction of the basic KBH4 solution catalyzed by Rh80Ag20 bimetallic NPs was about 47.0 ± 3.9 kJ mol−1.