NiFe Layered Double Hydroxide Electrocatalysts for an Efficient Oxygen Evolution Reaction

Alkaline electrolysis is one of the most promising among gas-to-power technologies to produce hydrogen energy where the oxygen evolution reaction (OER) plays an important role. It has recently been demonstrated that the OER activity of layered double hydroxide (LDH) could be enhanced by accommodating more abundant active sites that offer optimal binding energies between intermediates. Here, we report a study of nickel iron layered double hydroxides by varying the Ni:Fe atomic ratio of the Ni_1-xFe_x-LDH to induce changes to their physiochemical properties through which the optimum OER performance is determined. Optimized NiFe-LDH-38 (Ni_0.62Fe_0.38LDH) shows an excellent OER performance in alkaline electrolyte, demonstrating a potential of 1.45 V (vs RHE) at 100 mA cm^-2, which outperforms the commercial RuO₂catalyst. Also, computational simulations support the OER performance of the single NiFe-LDH phase (NF-LDH-38). This work provides not only a fundamental understanding of the effect of the Ni:Fe atomic ratio of the Ni_1-xFe_x-LDHs on OER performance but also the design strategy of low-cost, earth abundant, and active electrocatalysts toward water oxidation.