Microenvironmental Tuning in Isostructural Conjugated Metal–Organic Frameworks for Superior Photocatalytic H ₂ O ₂ Generation

Photocatalytic hydrogen peroxide (H 2 O 2 ) generation via sunlight‐driven water and oxygen reduction reactions presents a sustainable alternative to the energy‐intensive anthraquinone process. Although metal–organic frameworks (MOFs) offer tunable platforms for photocatalysis, the influence of metal–ligand microenvironment modulation within isostructural systems remains largely unexplored. In this work, we report two chemically robust conjugated 3D MOFs, Mn‐Tp and Fe‐Tp , synthesized via a scalable, solvent‐free mechanochemical route and their exploration as photocatalysts. Despite sharing identical topologies and morphologies, Mn‐Tp exhibits markedly superior photocatalytic performance, achieving a remarkable H 2 O 2 yield of 10,487 µmol g −1 h −1 , an apparent quantum yield of 9.94% at 467 nm, and a solar‐to‐chemical conversion efficiency of 0.45%. Mechanistic investigations, supported by theoretical calculations, reveal that subtle differences in the metal‐node microenvironment modulate the electronic structure, promote dual‐channel H 2 O 2 generation via oxygen reduction and water oxidation, and suppress decomposition pathways. This study highlights the crucial role of local redox tuning in enhancing photocatalytic functionality, providing a strategic blueprint for designing next‐generation MOF‐based catalysts for the sustainable production of oxidants.