Self-Assembly of Hierarchical Ni-Mo-Polydopamine Microflowers and their Conversion to a Ni-Mo C/C Composite for Water Splitting.

With the aim of finding efficient non-noble metal catalysts for water splitting, hierarchical Ni-Mo-polydopamine microflowers (Ni-Mo C/C MF) were synthesized through a facile aqueous-phase reaction at room temperature. NiMoO nanowires were utilized as both Ni and Mo source; they can complex with dopamine to form a hierarchical structure and affect the scale of the final product. The energy dispersive spectroscopy (EDS) measurement of Ni-Mo C/C microflowers (MF) shows a high content of Mo C and Ni (>90 wt %). For the hydrogen evolution reaction (HER), the Ni-Mo C/C MF displays a low overpotential of 99 mV at a current density of -10 mA cm and a small Tafel slope of 73 mV dec in 1.0 m KOH. By comparison with Mo C/C microspheres (MS), the nanosized Ni-doped particles offer more active sites and enhance the kinetic performance. This facile synthesis strategy is also suitable for preparing other metal-Mo C/C composites that can be used in the fields of catalysis and energy conversion.