Ligand‐Engineered Metal–Organic Cages Boost Charge Separation for Efficient Photocatalytic Synthesis of Hydrogen Peroxide in Pure Water

ABSTRACT Photocatalytic synthesis of hydrogen peroxide (H 2 O 2 ) offers a sustainable alternative to the traditional anthraquinone process, yet its efficiency is often hampered by the rapid recombination of photogenerated charges and the instability of reactive intermediates. Herein, we report a tetrahedral Zn(II) ion coordinated metal−organic cage ( MOC ) C3 constructed from a C 3 ‐symmetric terpyridine ligand incorporating pyridinium units. In pure water under an O 2 atmosphere and without sacrificial agents, C3 exhibits an H 2 O 2 generation rate of 678.15 µmol L −1 h −1 . Moreover, the confined cavity of the MOC is proposed to help stabilize crucial intermediates (*OH from water oxidation and *OOH from oxygen reduction), thereby further promoting the catalytic performance. This work illustrates a ligand‐engineering strategy for photocatalyst design by employing functionalized ligands to construct MOC that primarily improve charge‐separation efficiency and create directional electron‐transfer channels within the cage framework, while the confined microenvironment secondarily stabilizes key reactive intermediates, thus offering a route toward advanced photocatalytic H 2 O 2 generation.