Electrochemically Exfoliated β-Co(OH)₂ Nanostructures for Enhanced Oxygen Evolution Electrocatalysis

Abstract

Exploring highly efficient and low-cost electrocatalysts for the oxygen evolution reaction (OER) is very important for the development of renewable energy conversion and storage systems. Layered metal hydroxides have been studied with great interest owing to their high electrochemical activity and stability toward OER. Herein, we demonstrate an efficient approach to engineer the surface active sites in β-Co­(OH)2 for enhanced electrocatalysis of OER. We employ a single-step bipolar electrochemical technique for the exfoliation of pristine β-Co­(OH)2(Co­(OH)2-Bulk) into thinner and smaller sheets. The as-synthesized Co­(OH)2 nanostructures with improved active sites exhibit enhanced electrocatalytic activity toward OER with a very low overpotential of 390 mV at 10 mA cm–2 and a Tafel slope of 57 mV dec–1 in alkaline media. The results provide a promising lead for the development of efficient and economically viable electrode materials for oxygen evolution electrocatalysis.

Recent Advances in Manifold Exfoliated Synthesis of Two‐Dimensional Non‐precious Metal‐Based Nanosheet Electrocatalysts for Water Splitting

“…[ 5–9 ] However, precious metal‐based electrocatalysts are hard to be used in large scale of commercial applications, due to their high costs, poor stability, and low abundance in natural resources. Consequently, numerous low‐cost electrocatalysts based on earth‐abundant elements, such as metal oxides/hydroxides, [ 1,10–16 ] transition metal dichalcogenides (TMDs), [ 2,17–24 ] transition metal carbides and nitrides (TMNs and MXenes), [ 25–32 ] heteroatom‐doped carbons, [ 33–35 ] layered double hydroxides (LDHs), [ 36–38 ] metal–organic frameworks (MOFs), [ 39–42 ] monoelemental catalysts, [ 43–45 ] etc., have been developed to replace noble metal‐based electrocatalysts for water splitting. [ 3,46,47 ]…”

Anchoring γ-MnO2 within β-NiCo(OH)2 as an Interfacial Electrode Material for Boosting Power Density in an Asymmetric Supercapacitor Device and for Oxygen Evolution Catalysis

“…Particularly, the electrocatalyst made up of Ni, Co, or Mn metal ions is generally employed as rich redox active materials, which exhibit an excellent electrical conductivity . Shaijumon et al have described the synthesis of the exfoliated β-Co­(OH) 2 electrocatalyst via a single-step bipolar electrochemical technique to show the low overpotential of 390 mV at a 10 mA/cm 2 current density and Tafel slope of 57 mV dec –1 for OER . Accordingly, in the present investigation, for the first time, we attempt to introduce phase-oriented such as α-MnO 2 or γ-MnO 2 at β-NiCo­(OH) 2 via the one-pot hydrothermal method to explore the bifunctional electrode properties such as ES properties and as an electrocatalyst to study OER.…”

“…Among the different electrocatalyst, β-NiCo­(OH) 2 /γ-MnO 2 electrocatalyst-loaded electrode adsorbs OH – at a very low overpotential of η = 700 mV to reach the current density of 10 mA/cm 2 (Figure c). Briefly, during LSV studies, NiCo­(OH) 2 and MnO 2 have changed into NiOOH (Ni 3+ ), CoOOH (Co 3+ ), and MnOOH (Mn 3+ ) oxy (hydroxides) and returned back to their original phase during the cyclic study. ,, Thereby, the oxidation and reduction peaks appeared at 0.37 and 0.22 V before and after cycles of LSV curves, indicating that the well-defined nanostructure of β-NiCo­(OH) 2 /γ-MnO 2 offers more surface active sites for enhanced electrocatalytic OER performance. Besides, the slight change in the LSV curves after the 1000 cycle was observed for all electrocatalysts.…”

Hierarchical Design of Co(OH)2/Ni3S2 Heterostructure on Nickel Foam for Energy Storage

“…Inspired by the above discussion, we designed and constructed a Co(OH) 2 /Ni 3 S 2 heterostructure on nickel foam, which not only gives full play to the energy storage characteristics of each component but also makes full use of the skeleton support function of Co(OH) 2 flakes, which provide sufficient exposed active sites from the perspective of structural design [12,17]. As for the specific preparation route, a three-electrode system was adopted to perform two-step electrodeposition according to previous reports with some modifications; that is, Co(OH) 2 nanoflakes were first grown on nickel foam by galvanostatic deposition, and then Ni 3 S 2 was coated on the surface of Co(OH) 2 by potentiostatic deposition.…”