Dimensional Engineering of Covalent Organic Frameworks Enables Chain–Chain Cooperative Water Adsorption for Selective Electrosynthesis of Hydrogen Peroxide

ABSTRACT The adsorption and dissociation of water molecules at the catalyst‐electrolyte interface dictate the activity and selectivity of the electrochemical two‐electron oxygen reduction reaction to H 2 O 2 . In this work, we report the deliberate dimensional engineering of phenanthrenequinone‑based covalent organic frameworks (PQ‑COFs) to boost H 2 O 2 electrosynthesis via chain–chain cooperative water adsorption. Two isomeric COFs with well‑defined 1D and 2D architectures were constructed via condensation of V‑shaped or linear PQ di‐amines with a tetra‑aldehyde linker. Comprehensive characterizations confirm the formation of crystalline, imine‑linked frameworks with integrated redox‑active PQ units. Electrochemical evaluations reveal that the 1D COF exhibits superior activity and selectivity (H 2 O 2 selectivity up to 87.7%) compared to its 2D analogue, delivering a stable H 2 O 2 yield of 244 mg L −1 after 100 min of electrolysis in an H‑type cell. Mechanistic studies demonstrate that the closely packed 1D chains enable cooperative inter‑chain interactions, which strengthen interfacial water adsorption and reorganize hydrogen‐bonded water networks. The dynamic aqueous microenvironment accelerates water dissociation and proton transport, while optimizing the binding energy of critical intermediates to favor selective H 2 O 2 generation.