Janus‐Architected HEA‐Mo ₂ C Heterophase Catalysts with Self‐Optimizing Interfaces for Efficient Alkaline Seawater Electrooxidation

Abstract Direct seawater electrolysis represents a cornerstone technology for sustainable hydrogen production, yet anode materials face persistent challenges from chloride‐induced corrosion and competitive oxidation reactions. Herein, a Janus‐architected heterophase catalyst (HEA‐Mo ₂ C) synthesized through a flash Joule‐heating method is demonstrated. The heterophase architecture enables dynamic interface reconstruction under operational conditions and forms a chloride‐repulsion shield through molybdate (MoO ₄ ²⁻ ) generation on the active high‐entropy alloy (HEA). Crucially, this biphasic configuration demonstrates self‐adaptive surface reconfiguration that synergistically balances corrosion resistance and catalytic efficiency in alkaline seawater. When deployed in anion‐exchange membrane electrolyzers, the heterostructured catalyst achieves industrial‐grade current density (1 A cm ⁻² at 1.96 V) with excellent stability over 1000 h at 500 mA cm ⁻² . Mechanistic studies reveal that the sustained performance originates from the continuous interface remodeling between metallic HEA domains and carbide‐mediated protective layers. This work establishes heterophase interface engineering as a paradigm for designing durable seawater oxidation electrocatalysts.