Pulsed Laser Transformed High-Entropy Metal (Oxy)Hydroxide for Highly Active Seawater Oxidation with an Operational Robustness over 400 Hours

Oxygen evolution reaction (OER) is critical to renewable energy conversion technologies such as water electrolyzers, though OER remains constrained by sluggish kinetics and catalyst instability. High-entropy materials (HEMs) have emerged as promising catalysts due to their multi-elemental synergistic effects. However, their synthesis often involves complex processes or ingot precursors with complicated preparation procedures. Herein, we develop a versatile strategy for synthesizing high-entropy metal (oxy)hydroxide (HEMO) catalysts starting with solution-processable multi-metallic hydroxide (MMOH) precursors generated by co-precipitation, followed by nanosecond pulsed laser transformation under a 5% H2/N2 atmosphere. This direct method ensures product homogeneity by using well-mixed precursors, and the mild preparation conditions of MMOHs circumvent HEM synthesis complexity, enabling exploration of diverse metal combinations. In this work, high-entropy NiCoFeMnBi (oxy)hydroxide (HEMO-NiCoFeMnBi) is synthesized from MMOH-NiCoFeMnBi and serves as an efficient OER catalyst with double the mass activity compared to its precursor. HEMO-NiCoFeMnBi exhibits an onset potential of 1.46 V vs. RHE in alkaline and >400-hour durability in simulated seawater. This work not only establishes a scalable laser transformation platform for fabricating HEMOs as efficient and stable OER catalysts but also accelerates the discovery and application of HEMs to realize sustainable energy frameworks.