Performance study of amorphous NiB alloys modified by Mo as electrocatalysts for borohydride oxidation

In this study, amorphous Ni-B-Mo-x/C alloy catalysts are prepared by a convenient way of chemical reduction. The activity of the Ni-B-Mo/C catalysts with various ratios of Mo to B toward electro-oxidation of borohydride in alkaline solutions is studied by means of cyclic voltammetry (CV), linear scan voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). The result of transmission X-ray diffraction (XRD) shows the Ni-B or Ni-B-Mo-x nanoparticles has an amorphous structure. The scanning electron microscopy (SEM) demonstrates the Ni-B-Mo-x amorphous nanoparticles is uniformly spherical morphology and has improved dispersity. It has been determined that the Ni-B-Mo-x/C nanoparticles have higher activity toward borohydride electro-oxidation than the Ni-B/C nanoparticles, and the borohydride oxidation current of Ni-B-Mo-x/C amorphous nanoparticles initially increases and then decreases with the increase in Mo content. The Ni-B-Mo-0.05/C amorphous nanoparticles show the best electro-oxidation for BH4-. Additionally, the surface coverage of redox species of the Ni-B-Mo-0.05/C is about 3 times that of Ni-B/C, which is conducive to sodium borohydride adsorption, thereby improving the electrocatalytic activity for BH4- oxidation. Therefore, amorphous Ni-B-Mo-x alloy nanoparticles are a very promising catalyst to be used in direct borohydride fuel cell for borohydride oxidation reaction.

Automated summary

Amorphous Ni-B-Mo-x/C alloy catalysts were prepared by chemical reduction and studied for their activity towards borohydride electro-oxidation. The nanoparticles showed improved catalytic activity with increasing Mo content, making them promising catalysts for borohydride oxidation in direct borohydride fuel cells.