Building Ultrathin MOL/MOL S‐Scheme Heterostructures Toward Boosted Photocatalytic Charge Kinetics for Efficient H2 Evolution

Photocatalytic efficiencies highly depend on the kinetic behaviors of photogenerated electrons in catalysts. Herein, based on the promising metal‐organic frameworks (MOFs), we design and build an advantageous architecture of ultrathin MOF‐layer (MOL) heterojunctions by a facile pH‐adjusted electrostatic assembling of pre‐exfoliated porphyrinic and pyrene‐based MOLs. Such an architecture constitutes an S‐scheme junction to drive interfacial charge separation, features ultrathin structures to shorten charge transfer distances, and maximizes accessible metal sites to facilitate terminal charge reaction, thoroughly promoting the charge kinetics in materials. The resulting MOL/MOL composites perform a significantly enhanced catalytic activity for visible‐light‐driven H2 evolution, 8.5 and 106 times that of individual MOLs. Further fine‐tuning into more reactive metal nodes achieves an optimal H2 production (2027 μmol·h‐1·g‐1) with a high apparent quantum yield of 2.75% without additional cocatalysts, ranking among state‐of‐the‐art activities from all‐MOF photocatalysts. This work demonstrates an accessible and universal methodology to realize a superior ultrathin MOL/MOL heterojunction architecture toward accelerated charge kinetics, providing valuable insights for the development of efficient photocatalyst systems for solar‐to‐chemical energy conversions.