Recent Advances in Biomimetic Electrocatalysts for Water Splitting: Emerging Trends and Outlook

Electrochemical water splitting offers a sustainable pathway for green hydrogen production; however, it remains constrained by the sluggish kinetics of the hydrogen evolution and oxygen evolution reactions. Nature's metalloenzymes, such as [FeFe] hydrogenases and the Mn₄CaO₅ cluster in photosystem II, exemplify exceptional catalytic efficiency using earth-abundant metals via proton-coupled electron transfer and cooperative metal-site interactions. This review highlights the advances in biomimetic electrocatalysts and traces their evolution from molecular analogs to heterogeneous systems, including oxygen-evolving complex mimic Mn/Ca clusters, biomimetic metal-porphyrinoids, metal-organic and covalent frameworks, nanostructured layered double hydroxides, Janus chalcogenides, high-entropy alloys, and single-atom catalysts. Hierarchical, self-healing, and dynamically stable architectures that sustain catalytic activity under operational stress are emphasized, supported by ultrafast operando spectroscopies that capture real-time active-site transformations. Emerging strategies, such as decoupled water splitting, direct seawater electrolysis, and the integration of machine learning and digital twin frameworks, are accelerating predictive catalyst design and system-level optimization. Adapting bioinspired design principles into electrolyzer architectures further enhances system efficiency. Despite meaningful advances, biomimetic systems remain hampered by their constrained durability, synthetic scale-up challenges, and unresolved mechanistic intricacies. Their progress toward practical electrolyzer technologies hinges on the concerted integration of bioinspired design, material innovation, and high-fidelity characterization.