Electrochemical Oxidation of Chlorine-Doped Co(OH)₂ Nanosheet Arrays on Carbon Cloth as a Bifunctional Oxygen Electrode

Abstract

The primary challenge of developing clean energy conversion/storage systems is to exploit an efficient bifunctional electrocatalyst both for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with low cost and good durability. Here, we synthesized chlorine-doped Co(OH) in situ grown on carbon cloth (Cl-doped Co(OH)) as an integrated electrode by a facial electrodeposition method. The anodic potential was then applied to the Cl-doped Co(OH) in an alkaline solution to remove chlorine atoms (electro-oxidation (EO)/Cl-doped Co(OH)), which can further enhance the electrocatalytic activity without any thermal treatment. EO/Cl-doped Co(OH) exhibits a better performance both for ORR and OER in terms of activity and durability because of the formation of a defective structure with a larger electrochemically active surface area after the electrochemical oxidation. This approach provides a new idea for introducing defects and developing active electrocatalyst.

MoP/Co2P Hybrid Nanostructure Anchored on Carbon Fiber Paper as an Effective Electrocatalyst for Hydrogen Evolution

“…The other two intense satellite peaks at 786.0 eV and 803.2 eV were attributed to shake up excitation of the high‐spin Co 2+ ions in the sample . The binding energy difference between the two main peaks (Δ=16.1 eV) indicated that Co existed in the form of Co(OH) 2 , which was consistent with previous studies …”

Spontaneous Synthesis of Silver‐Nanoparticle‐Decorated Transition‐Metal Hydroxides for Enhanced Oxygen Evolution Reaction

“…[8] For example, the large interlayer spacing and nanosheet (NS) structure of Co(OH) 2 are conducive to facilitate ion transport and provide large active area, respectively, which is vital to accelerate the OER kinetics in alkaline electrolytes. [9] However, Co(OH) 2 NS working as the anode catalyst of water electrolysis still cannot achieve ideal overpotential (lower than 300 mV at 10 mA cm À2 ), [10] indicating that the intrinsic activity of catalytic sites in Co(OH) 2 NS is limited. Consequently, it is critical to improve the catalytic efficiency and decrease the overpotential of Co(OH) 2 NS by engineering the surface atomic and electronic structures.Integrating metal nanoparticles with transition-metal compounds has been explored as a promising strategy to synthesize highly efficient electrocatalysts.…”

Self‐Assembled CoFe Nanoparticle‐Embedded Carbon Nanowires as Efficient Nonprecious Catalyst for Overall Water Splitting

“…As shown in Figure c, the C dl value is a linear slope of the plot, which is plotted by Δ J /2 (Δ J = J anodic − J cathodic ) at 0.95 V versus RHE versus scan rate . It is worth noting that the C dl value (8.46 mF cm −2 ) of CoFe@CNWs is much higher than those of Co@CNWs (3.56 mF cm −2 ) and Fe@CNWs (0.72 mF cm −2 ), suggesting that CoFe@CNWs possess larger electrochemically active area and more effective active sites for OER . Electrochemical impedance spectroscopy (EIS) is a powerful technique to characterize interfacial reactions and electrode kinetics in the OER process.…”

“…To date, the best electrocatalysts for HER and OER are platinum (Pt) and noble metal oxides (e.g., IrO 2 and RuO 2 ), respectively, which are normally scarce and expensive, leading to limitations in practicality . Moreover, most of other catalysts reported only have either HER or OER activity, which bring about additional cost during the synthesis of different materials . Hence, the current challenge is to develop a nonprecious, cost‐effective, and high‐stability electrocatalyst for both OER and HER as a potential alternative to noble metal‐based materials.…”