A novel electrocatalyst for oxygen evolution reaction based on rational anchoring of cobalt carbonate hydroxide hydrate on multiwall carbon nanotubes

Cobalt carbonate hydroxide hydrate (CCHH) nanosheets have been densely and strongly anchored onto mildly oxidized multiwalled carbon nanotubes with the assistance of diethylenetriamine (DETA). The resulted hybrid (CCHH/MWCNT) is used as high efficient electrocatalyst for water oxidation with an extremely low onset potential of ∼1.47 V vs. RHE and an overpotential of 285 mV to achieve a current density of 10 mA cm^-2 in 1.0 mol L^-1 KOH. The CCHH/MWCNT electrode affords a Tafel slope of 51 mV/decade and an exchange current density of 2.5 × 10^-7 A cm^-2. Moreover, the CCHH/MWCNT catalyst delivers a high faradic efficiency of 95% and possesses remarkable stability for long-term electrolysis of water. By contrast, neither MWCNT nor CCHH exhibits apparent catalytical activity towards water oxidation. Importantly, we demonstrate that DETA plays crucial role in determining the morphology, structure of the CCHH/MWCNT, therefore resulting in an enhanced performance for water oxidation. This work not only provides a novel cobalt-based electrocatalyst for oxygen evolution, but also offers a useful and viable approach to deliberately synthesize functional nanocomposites for applications in energy conversion and storage.