Self-Assembly of Hierarchical Ni-Mo-Polydopamine Microflowers and their Conversion to a Ni-Mo2C/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 2 C/C MF) were synthesized through a facile aqueous-phase reaction at room temperature. NiMoO 4 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 2 C/C microflowers (MF) shows a high content of Mo 2 C and Ni (>90 wt %). For the hydrogen evolution reaction (HER), the Ni-Mo 2 C/C MF displays a low overpotential of 99 mV at a current density of −10 mA cm −2 and a small Tafel slope of 73 mV dec −1 in 1.0 m KOH. By comparison with Mo 2 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 2 C/C composites that can be used in the fields of catalysis and energy conversion. Graphical In flower : A flowerlike Ni-Mo-dopamine complex is first synthesized by a facile method under room temperature. Ni doping in situ is realized by utilizing NiMoO 4 nanowire as both template and precursor. An enlarged surface area and nanosized Ni doping greatly enhance the electrocatalytic properties of Ni-Mo 2 C/C due to more active sites.