Defect-Rich\nUltrathin Cobalt–Iron Layered Double\nHydroxide for Electrochemical Overall Water Splitting

Abstract

Efficient and durable electrocatalysts\nfrom earth-abundant elements\nplay a vital role in the key renewable energy technologies including\noverall water splitting and hydrogen fuel cells. Here, generally used\nCoFe based layered double hydroxides (LDHs) were first delaminated\nand exfoliated in the DMF-ethanol solvent (CoFe LDH-F), with enhancement\nboth in oxygen evolution reaction (OER) and hydrogen evolution reaction\n(HER). The exfoliation process creates more coordinatively unsaturated\nmetals and improves the intrinsic electronic conductivity, which is\nimportant in water electrolyzer reactions. In the basic solution,\nthe CoFe LDH-F catalyst outperforms the commercial iridium dioxide\n(IrO₂) electrocatalyst in activity and stability for OER\nand approaches the performance of platinum (Pt) for HER. The bifunctional\nelectrocatalysts can be further used for overall water splitting,\nwith a current density of ∼10 mA/cm² at the applied\nvoltage of 1.63 V for long-term electrolysis test, rivalling the performance\nof Pt and IrO₂ combination as benchmarks. Our findings\ndemonstrate the promising catalytic activity of LDHs for scale-up\nalkaline water splitting.