Production of a new 3D electrode skeleton of Ni with very high electrochemical surface area for oxygen evolution

Abstract

Long and stable fibers (Tapes) of nickel with a thickness that can reach less than one hundred nanometers were produced through directional solidification of Ni-Al hypereutectic alloy on the surface of Ni and then, leaching the alloy in potassium hydroxide solution. Experimental results illustrated that the structure of the tapes is Raney nickel. In other words, a 3D structure consisting of a large number of Nano-dimensional tapes with a Nano-porous and Nano-crystalline structure was created. The activity of this structure was evaluated for oxygen evolution in alkaline media. The results showed that by increasing the number of Tapes per 〖cm〗^2 (density of Tapes), electrochemical surface area and double layer capacitance increase. As the density of Tapes increases, the OER overpotential decreases, but with further increase in density of Tapes, the OER overpotential increases again. Re-increase in overpotential was associated to trapping of oxygen bubbles. The best sample showed an overpotential 240 mV at 10 mA/〖cm〗^2 and 350 mV at 500 mA/〖cm〗^2. Also, this sample worked without any sign of degradation at 500 mA/〖cm〗^2 for 6 days (144 hours).