2D macromolecular cobalt-doped nickel-iron-layered double hydroxide lattice building blocks for highly efficient...

The oxygen evolution reaction (OER) is a primary challenge in water splitting due to its complex, sluggish, and four-electron transfer nature. Thus, a catalyst with a high active surface area, low resistance, low cost, effective, efficient, and environmentally friendly is required for real-time applications. The development of 2D macromolecules of water-exfoliable transition metal-doped layered double hydroxide (LDH) can exhibit numerous active sites, high conductivity, and outstanding stability. Herein, we developed an effective and environmentally friendly synthesis of exfoliated 2D macromolecules Co-doped nickel‑iron-LDH nanosheets (CNFL-NS) and utilized them to deposit thin films via the electrophoretic deposition (EPD) method on stainless steel substrates, thus enhancing the electrocatalytic OER performance. The 2D-CNFL-NS2 electrocatalyst exhibits a lower overpotential of 245 mV to reach 50 mA cm^-2 and retains outstanding kinetics with a small Tafel slope of 39 mV dec^-1. The electrochemical impedance spectroscopy (EIS) spectrum reveals a lower charge transfer resistance (0.81 Ω), which is significantly lower than that of CNFL-B (8.1 Ω). Moreover, the exfoliation strategy shows a higher electrochemical active surface area (ECSA) of 13.5 cm² and exhibits outstanding electrocatalytic stability over 100 h at 100 mA cm^-2 current density during a chronoamperometric test, which demonstrates the robustness of the catalyst. This remarkable finding provides a platform for exfoliating LDH NS and depositing LDH NS as a highly efficient electrocatalyst thin film for OER.