Efficient Hydrogen and Oxygen Evolution: Dual-Functional Electrocatalyst of Zinc Iron Layered Double Hydroxides and Nickel Cobalt Sulfides on Nickel Foam for Seawater Splitting

Hydrogen, derived from water splitting, holds promise as a sustainable energy carrier. However, replacing fossil fuels demands large volumes of pure water, a resource that is scarce in numerous regions globally. This study focuses on developing an efficient electrocatalyst for seawater splitting, aiming to conserve freshwater resources and overcome the challenges associated with direct utilization of seawater. Zinc iron layered double hydroxides combined with nickel cobalt sulfides on nickel foam (ZnFe LDH@NiCoS/NF) are produced to operate efficiently in alkaline seawater splitting, which involves the evolution reactions of hydrogen and oxygen. Through the utilization of an alkalinized electrolyte and suitable nickel foam substrates, the adverse effects of corrosion and chlorine oxidation reactions are effectively mitigated. The composite ZnFe LDH@NiCoS/NF exhibits exceptional electrocatalytic efficacy in alkaline seawater, needing remarkably minimal overpotentials of 246.3 mV for the hydrogen evolution reaction (HER) and 284.8 mV for the oxygen evolution reaction (OER) to attain the targeted current density. Additionally, the composite electrocatalyst exhibits decreased Tafel values of 74.6 mV dec^–1 for the hydrogen evolution reaction (HER) and 81.5 mV dec^–1 for the oxygen evolution reaction (OER), suggesting enhanced kinetics. This improved electrocatalytic performance is attributed to the increased surface area and decreased charge transfer resistance. Additionally, the catalytic electrode exhibits impressive long-term stability, maintaining efficiency for approximately 50 h at a constant current density for both the HER and the OER. This study emphasizes the innovative character of ZnFe LDH@NiCoS/NF as a crucial breakthrough in research on bifunctional electrocatalysts for the HER and the OER, presenting a hopeful direction for harnessing renewable energy from seawater.