Constructing Amorphous‐Crystalline Interfacial Bifunctional Site Island‐Sea Synergy by Morphology Engineering Boosts Alkaline Seawater Hydrogen Evolution

Abstract The development of efficient and durable non‐precious hydrogen evolution reaction (HER) catalysts for scaling up alkaline water/seawater electrolysis is highly desirable but challenging. Amorphous‐crystalline (A‐C) heterostructures have garnered attention due to their unusual atomic arrangements at hetero‐interfaces, highly exposed active sites, and excellent stability. Here, a heterogeneous synthesis strategy for constructing A‐C non‐homogeneous interfacial centers of electrocatalysts on nanocages is presented. Isolated PdCo clusters on nanoscale islands in conjunction with Co 3 S 4 A‐C, functioning as a bifunctional site “island‐sea” synergy, enable the dynamic confinement design of metal active atoms, resulting in excellent HER catalytic activity and durability. The hierarchical structure of hollow porous nanocages and nanoclusters, along with their large surface area and multi‐dimensional A‐C boundaries and defects, provides the catalyst with abundant active centers. Theoretical calculations demonstrate that the combination of PdCo and Co 3 S 4 regulates the redistribution of interface electrons effectively, promoting the sluggish water‐dissociation kinetics at the cluster Co sites. Additionally, PdCo‐Co 3 S 4 heterostructure nanocages exhibit outstanding HER activity in alkaline seawater and long‐term stability for 100 h, which can be powered by commercial silicon solar cells. This finding significantly advances the development of alkaline seawater electrolysis for large‐scale hydrogen production.