Interfacial atomic engineering of epitaxial core-shell heterostructures for high-performance overall water splitting and anion exchange membrane electrolyzer

Alkaline water electrolysis plays a vital role in large-scale hydrogen production. Designing effective and durable bifunctional electrocatalysts are crucial for achieving high-efficiency HER and OER process. Herein, a novel core-shell WS₂@WSe₂ heterostructure with abundant active interfaces is designed and synthesized by in-situ van der Waals epitaxial growth. Numerous characterizations and theoretical simulations prove the successful construction of heterostructure and its advantage on optimizing the adsorption strength of hydrogen and oxygen intermediates, thereby enhancing the reaction kinetics for both HER and OER. Benefiting from the electronic modulation at catalytic interface, the heterostructure achieves a low cell voltage of 1.91 V at 100 mA cm⁻² with a remarkable stability in a water electrolyzer. The anion exchange membrane water electrolyzer (AEMWE) catalyzed by WS₂@WSe₂ can achieve a high current density of 1000 mA cm⁻² at 2.23 V with a long-term stability over 70 h. This study offers a new perspective on designing high-activity electrocatalysts through in-situ van der Waals epitaxial growth in energy conversion applications.