Preparation of dendritic NiFe films by electrodeposition for oxygen evolution

Abstract

Dendritic materials are attractive as catalysts due to their highly ordered structure and high surface area. Herein, we report a NiFe dendritic nanostructure obtained by a simple electrodeposition without template. The control of concentration, potential, and pH plays an important role in the formation of the dendritic nanostructures. The longer and thinner NiFe dendritic nanostructure was obtained by changing the potential from −1.1 to −1.3 V vs. Ag/AgCl and a highly ordered nanostructure was obtained at the low pH of 2. NiFe dendritic material obtained at a potential of −1.3 V in pH 2.00 at 0.025 M NiSO₄ and 0.025 M FeSO₄ has a three-dimensional nanostructure. The growth mechanism of the NiFe dendritic nanostructure was investigated by SEM and the ED pattern of TEM. EDS, XRD, and XPS were used to investigate elemental composition, crystalline structure, and the chemical state of the as-obtained NiFe dendritic material. The efficiency of water-oxidation catalysts is critically influenced by the surface conditions and controlling the surface state is a major factor in developing an artificial photosynthetic system which stores the sunlight energy by water-splitting and carbon dioxide reduction in aqueous solution. Hence, we tested the NiFe dendritic nanomaterial as an oxygen-evolving catalyst and found that it shows oxygen evolution at 0.44 V vs. Ag/AgCl in 1 M NaOH solution.