Flower-like Co nano-particles deposited on Ni foam substrate as efficient noble metal-free catalyst for hydrazine oxidation

• Flower-like Co nano-particles are deposited on Ni foam via electrodeposition.
• Co NFs/Ni foam electrode shows high catalytic activity for hydrazine electrooxidation.
• The single Co nano-flower actually consisted of many ultrathin nano-sheets.

Ni foam supporting flower-like Co nano-particles (Co NFs/Ni foam) are successfully synthesized by a simple electrochemical method. The electrodes are characterized by scanning electron microscopy equipped with an energy dispersive X-ray spectrometer, and X-ray diffractometer. Without any conducting carbons and polymer binders, the 3D electrode with a unique structure is directly used as the noble metal-free catalyst for hydrazine oxidation and the catalytic performance is evaluated by voltammetry and chronoamperometry. The Co NFs/Ni foam electrode exhibits excellent catalytic performance and superior stability for hydrazine electrooxidation in alkaline media. In the solution of 1.0 mol L− 1 NaOH + 30 mmol L− 1 N2H4, the oxidation current density at − 0.8 V is 140 mA cm− 2 for the Co NFs/Ni foam electrode, and it is only 42 mA cm− 2 for the Pt/Ni foam electrode. Also, the onset potential for Co NFs/Ni foam electrode can reach to − 1.06 V (only − 0.72 V for Ni foam), suggesting that the high cell voltage of DHFC with Co NFs/Ni foam anode. These merits are benefitting from the unique 3D structure which can ensure high utilization of catalysts.