Electrocatalytic Oxidation of Sodium Borohydride on a Nanoporous Ni/Zn-Ni Electrode

A Ni-Zn binary metal coating was electrochemically deposited on a copper electrode that was coated with nickel (bottom layer). This was then etched in concentrated alkaline solution (30 wt% NaOH) to produce a nanoporous Ni electrocatalytic surface for borohydride electro-oxidation in alkaline solution. The bulk and surface compositions of the coating before and after alkaline leaching were determined by atomic absorption spectroscopy and energy dispersive X-ray analysis. The surface morphology was investigated by scanning electron microscopy. The characterization showed that the leached Ni/Zn-Ni coating has a nanoporous structure. Electrocatalytic activity for borohydride electro-oxidation was assessed by cyclic voltammetry and electrochemical impedance spectroscopy. The improved activity of the electrode was related to the removal of corrosion products and the formation of nanopores and cracks during alkaline leaching. Cyclic voltammetry studies confirmed that the alkaline leaching process improved the activity of the Ni/Zn-Ni coating in comparison to that of a smooth Ni deposit, and it gave an anodic peak current density that was 21 times higher.

A leached Ni/Zn-Ni electrode showed a significantly higher electrocatalytic activity for borohydride oxidation than a smooth nickel electrode, which was attributed to the higher surface area and changes in surface features.Figure optionsDownload as PowerPoint slide