Synergistic Integration of Metal‐Organic Ring and Cyano‐COF in Z‐Scheme for Stable H ₂ Production With Single‐Atom Pd Sites

The development of robust and efficient photosystems is crucial for solar‐driven H 2 production. Herein, a supramolecular photosystem is constructed by immobilizing a photosensitive metal‐organic ring (MAC‐KB1) onto a cyano‐functionalized covalent organic framework (BT‐CN‐COF). The formed heterointerface facilitates supramolecular interactions and enables the formation of a direct Z‐scheme charge transfer pathway. The optimal composite achieves an excellent H 2 evolution rate of 32.13 mmol g −1 h −1 and shows no significant activity decay after 130 h of reaction, representing one of the most stable COF‐based photocatalysts. Mechanism studies reveal that the cyano groups in the COF optimize electron distribution, while the single‐atom Pd sites in the metal‐organic ring act as highly active catalytic centers. The synergistic effect of enhanced light absorption, efficient Z‐scheme charge separation, and atomic‐level utilization of Pd contributes to the superior and stable photocatalytic performance. This work provides a novel design strategy for constructing highly efficient and stable supramolecular photosystems for solar‐to‐fuel conversion.