Development of Cobalt Hydroxide as a Bifunctional Catalyst for Oxygen Electrocatalysis in Alkaline Solution

Abstract

Co(OH)2 in the form of hexagonal nanoplates synthesized by a simple hydrothermal reaction has shown even greater activity than cobalt oxides (CoO and Co3O4) in oxygen reduction and oxygen evolution reactions (ORR and OER) under alkaline conditions. The bifunctionality for oxygen electrocatalysis as shown by the OER-ORR potential difference (ΔE) could be reduced to as low as 0.87 V, comparable to the state-of-the-art non-noble bifunctional catalysts, when the Co(OH)2 nanoplates were compounded with nitrogen-doped reduced graphene oxide (N-rGO). The good performance was attributed to the nanosizing of Co(OH)2 and the synergistic interaction between Co(OH)2 and N-rGO. A zinc-air cell assembled with a Co(OH)2-air electrode also showed a performance comparable to that of the state-of-the-art zinc-air cells. The combination of bifunctional activity and operational stability establishes Co(OH)2 as an effective low-cost alternative to the platinum group metal catalysts.

Effective Construction of High-quality Iron Oxy-hydroxides and Co-doped Iron Oxy-hydroxides Nanostructures: Towards the Promising Oxygen Evolution Reaction Application

“…The first one was the branch structure on the surface providing many active edge sites, enhanced mass/charge transport capability, easy release of oxygen gas bubbles, and strong structural stability, which are advantageous for OER40. The main reason was that the Co-doping in FeOOH nanostructures constituted a desirable four-electron pathway for reversible oxygen evolution and reduction, which is potentially useful for rechargeable metal−air batteries, regenerative fuel cells, and other important clean energy devices41. The charge transfer efficiency at the electrode interface was greatly improved after the Co doping into FeOOH nanostructure, which can be demonstrated by Nyquist plots for both catalysts (Fig.…”

Highly Active Cobalt‐Based Electrocatalysts with Facile Incorporation of Dopants for the Oxygen Evolution Reaction

“…Themorphology of the cobalt species was confirmed by transmission electron microscopy (TEM). [23] Ther esult demonstrates the role of Nafion as not only abinder but also astabilizer preventing the agglomeration of cobalt species.As shown in energy-dispersive X-ray (EDX) spectra (Figures S9f and S10g), the iron element was not detected before electrochemical activation, which supports that iron was provided by the electrolyte during activation. On the other hand, in the presence of Nafion, the bulky and nanoparticulated cobalt species were mixed together before and after electrochemical activation in nonpurified 1m KOH (Figures S9 and S10);t heir shape was dissimilar to those of typical cobalt hydroxide and oxyhydroxide.…”

Nanostructured catalysts for electrochemical water splitting: current state and prospects

“…In order to exploit high efficient alternative OER electrocatalysts, numerous Co based catalysts such as metal oxides 173 , hydro(oxy)oxides [173][174][175] , perovskites 176 , sulfides 177,178 , nitride 179 superior HER electrocatalytic activity 23 , but they are also attracted tremendous attentions for OER application because of their exceptional 3d electronic configurations 181 . However, even though some endeavours have been devoted to synthesize high stable metallic Co nanoparticles 172 , the Co metal is still unstable at high anodic potentials.…”