Cobalt-Nickel Wrapped Hydroxyapatite Carbon Nanotubes as a New Catalyst in Oxygen Evolution Reaction in Alkaline Media

Introducing an inexpensive non-noble metal electrocatalyst is an ongoing challenge in oxygen evolution reaction (OER). Here, a bimetallic cobalt-nickel-based catalyst is introduced by metal loading over hydroxyapatite multiwalled carbon nanotube substrate (Co-Ni/HA-MWCNTs). The proposed catalyst is promising and inexpensive and could be favorably applied in water electrolyzing systems. The HA-MWCNTs substrate was produced via the solid-state approach and the loading of Ni and Co species was achieved via the simple impregnation process. Structural characterization of the catalyst was achieved using transmission electron microscopy (TEM), X-Ray diffraction (XRD), and energy-dispersive X-ray analysis (EDX). Electrochemical efficiency of the catalyst for the OER was concluded from low onset potential at 1.50 V (vs RHE) with Tafel slope of 41.8 mV dec −1 . In comparison with the HA-free catalyst (Co-Ni/MWCNTs), the Co-Ni/HA-MWCNTs catalyst exhibits an excellent long-term stability up to 10,000 s to bear the current density of 10.0 mA cm −2 . Graphical Abstract