Amorphous FeOOH Quantum Dots on NiMn‐LDH Nanosheets for Highly Efficient Urea‐Assisted Overall Water Splitting

The development of low‐cost, earth‐abundant electrocatalysts is essential for advancing hydrogen‐based energy technologies, yet conventional water splitting remains constrained by the sluggish oxygen evolution reaction (OER). Substituting OER with the urea oxidation reaction (UOR) offers a more favorable alternative, reducing the reaction potential while simultaneously addressing wastewater remediation. Herein, we develop a heterostructured electrocatalyst of amorphous FeOOH quantum dots (QDs) uniformly anchored on NiMn layered double hydroxide (LDH) nanosheets grown on nickel foam (NF). The ultrathin conductive NiMn‐LDH scaffold offers high surface accessibility and tunable redox activity, while the FeOOH QDs introduce abundant active centers that accelerate charge transfer and optimize OH − and urea adsorption. As a result, FeOOH QDs/NiMn‐LDH/NF requires only a low overpotential of 1.42 V to reach 50 mA cm −2 for OER and 1.33 V for UOR, with small Tafel slopes of 31 and 29 mV dec −1 and exhibits outstanding long‐term durability of 50 h. Moreover, the heterostructured electrocatalyst shows competent activity for the hydrogen evolution reaction ( η 10 = 125 mV) and delivers an average Faradaic efficiency of ≈95.7% during electrolysis, confirming highly selective charge‐to‐hydrogen conversion. This enables efficient urea‐assisted overall water electrolysis at only 1.44 V. This work underscores the synergistic integration of LDH nanosheets with amorphous QDs as a versatile and scalable strategy to engineer next‐generation bifunctional electrocatalysts for energy‐efficient hydrogen production coupled with wastewater treatment.