Ni-Co-B catalyst-promoted hydrogen generation by hydrolyzing NaBH ₄ solution for in situ hydrogen supply of portable fuel cells

A series of Ni-Co-B catalysts were synthesized by a two-step technique, namely, chemical reduction was used to prepare the precursors, and heat-treatment was used to adjust the crystal structures. The structures of the as-prepared Ni-Co-B catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption test. The catalytic activities of the Ni-Co-B catalysts for NaBH₄ hydrolysis were evaluated in a successive hydrogen generation mode, where a 5%NaBH₄ + 1%NaOH solution was pumped into the hydrogen generation reactor with a feeding rate of 5 ml per minute. It is found that the heat-treatment affects the crystal structure, the apparent morphology, the oxidation state, the surface structure, as well as the hydrogen generation performances of the Ni-Co-B catalysts. The sample treated at 673 K achieves an average hydrogen generation rate of 708 ml min^-1 g^-1_catalyst, which can give successive hydrogen supply for an 115 W portable proton-exchange membrane fuel cell (PEMFC).