Defect Engineering of Metal–Organic Frameworks for Enhanced Proton Conductivity

This study successfully synthesized a metal–organic framework (MOF) material with high‐density defects, which exhibits exceptional proton conductivity (4.15 × 10 ⁻³  S cm ⁻¹ at 99% RH)—nearly two orders of magnitude higher than its low‐defect counterpart. Mechanistic investigations reveal that this enhancement originates from the HCOO ^– /HCOOH groups introduced at defect sites. These functional groups not only serve as strong acidic sites providing abundant proton sources but also establish continuous and robust hydrogen‐bonding networks with water molecules, enabling the MOF to achieve Grotthuss‐type proton conduction mechanism. This work demonstrates that constructing defects with specific functional groups represents an effective design strategy for developing high‐performance MOF‐based proton‐conductive materials.