Carbon Coated and Nitrogen Doped Hierarchical NiMo-Based Electrocatalysts with High Activity and Durability for Efficient Borohydride Oxidation

Sodium borohydride is a promising candidate as hydrogen storage material. The direct borohydride fuel cell (DBFC) as an energy conversation device has attracted intensive attention owing to the low theoretical potential of borohydride oxidation reaction (BOR, −1.24 V vs SHE) on the anode. In this paper, the hierarchical sea urchin-like NiMoN@NC coated by thin carbon layer with optimal BH4– adsorption characteristic was synthesized as a superior electrocatalyst toward BOR. In 1 M NaOH-0.05 M NaBH4, the BOR working potentials are only −55 and 44 mV at the current densities of 10 and 200 mA cm–2 on NiMoN@NC, respectively. Furthermore, the membrane-free DBFC using NiMoN@NC as anodic electrocatalyst shows a maximum power density of 67 mW cm–2 at room temperature with appreciative stability. This well-designed carbon coated and nitrogen doped transition-metal material with hierarchical nano/microstructure as a highly efficient electrocatalyst shows promising potential and bright prospects in electrocatalysis research and practical application for energy conversion systems of DBFC.