Cobalt-Nickel Loaded on Hydroxyapatite Wrapped Multiwalled Carbon Nanotubes as a New Catalyst for Oxygen Evolution Reaction

A new catalyst based on MWCNTs coated with Hydroxyapatite (HA) was used for oxygen evolution reaction (OER) in alkaline media by immobilizing Ni and Co in the HA/MWCNTs structure. The solid state approach was used for synthesis of HA/MWCNTs and simple impregnation method was applied for loading Ni and Co on the HA/MWCNTs [1]. The mono and bimetallic catalysts were casted on a glassy carbon electrode which was finally coated with a Nafion layer. Different conditions such as the percentage of HA, amount of Ni and Co in the impregnation solution and the loading of Nafion were optimized. Under the optimized conditions, the best activity for OER was obtained for the bimetallic catalyst containing Ni and Co (Fig. 1). In fact, the best OER result was achieved via loading of Ni and Co ions on 40% HA /MWCNTs composite from an equimolar (50mM) impregnation solution of Ni2+ and Co2+. The onset potential of 1.50 V (vs. RHE) and high stability during 10000s were achieved using this ideal catalyst.