Unravelling Electronic Structure, Surface Reconstruction, and Local Environment Effects in NiFe-LDH Anodes for Direct Seawater Electrolysis

Abstract Seawater electrolysis offers an effective and transformative paradigm to enable sustainable and renewable green hydrogen generation at the commercial scale. Nonetheless, seawater has a complex chemistry, which hinders the efficiency of seawater electrolysis. The constituents that complicate seawater chemistry include halide ions, heavy metallic Ca2+ and Mg2+ ions, organic compounds, and microorganisms, among others. Cl– ions are known for their corrosive impacts in seawater electrolysis due to competing chlorine evolution reactions (ClER). Multivalent cations such as Ca2+ and Mg2+ cause cathodic precipitation, which leads to severe fouling. The seawater impurities trigger many side reactions to make the process less efficient. Through this critical review, we explore the fundamentals of rationally designing nickel–iron layered double hydroxide (NiFe-LDH) anode materials for highly efficient and durable oxygen evolution reaction (OER). The review disclosed three interconnected issues, including (i) electronic structure engineering, (ii) surface reconstruction pathways, and (iii) local environment effects. A critical discussion is provided on the electronic modulation via an in-depth survey of d-band center intonations, heteroatom (metal, nonmetal, and dual atom) doping, and heterostructure or nanocomposite formation. These modulations efficiently optimize the intermediate adsorption energetics and OER selectivity. Discussion on various types of surface reconstruction mechanisms explores the dynamic evolution of interfacial changes on the catalyst, which can be controlled to fabricate durable chloride-resistant active phases. Also, case studies were used to discuss the impact of electrolytic composition, pH gradients, and electric field effects on the local environment and electrode stability. Besides, we also discussed the importance of developing operando characterization and ab initio modeling, essential for exploring structure–activity–selectivity relationships during long-term OER testing. At the end, we translated these principles into a comprehensive design framework and outlined critical directions for realizing industrially viable seawater electrolysis systems.