An Ultra‐Robust and 3D Proton Transport Pathways iHOF with Single‐Crystal Superprotonic Conductivity Around 0.4 S cm−1

• Published in: Advanced functional materials Vol. 34; no. 49
• Main Authors: Cao, Xiao‐Jie, Cao, Li‐Hui, Bai, Xiang‐Tian, Hou, Xiao‐Ying, Li, Hai‐Yang
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.12.2024
• Subjects: anisotropic; Bonding strength; Charge materials; Chemical bonds; Density functional theory; density functional theory calculations; Hydrogen; Hydrogen bonding; Intermolecular forces; ionic hydrogen‐bonded organic frameworks; Protons; Robustness; Self-assembly; Single crystals; superprotonic conductivity
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202409359

The weak intermolecular forces of hydrogen‐bonded organic frameworks (HOFs) make it relatively difficult to synthesize and design HOFs with superprotonic conductivity and robustness. The self‐assembly of ionic hydrogen bonding organic frameworks (iHOFs) through acid–base pairing strategies are possible on account of the rich hydrogen bonding, strong ionic bonding, and π–π stacking interactions and so on. Herein, a case of iHOF (iHOF‐16) with a three‐dimensional (3D) hydrogen bonding network is reported, the doughty ionic bond interactions in the structure and π–π stacking interactions between layers make it exhibits excellent thermal and chemical stability, it can maintain high crystallinity and robust structure even under extreme conditions. Importantly, iHOF‐16 exhibits highly anisotropic proton conductivity of 0.388, 5.56 × 10−3, and 3.25 × 10−4 S cm−1 in the direction of a‐axis, b‐axis, and c‐axis, respectively. The proton transfer paths of single crystal on each axis are calculated using density functional theory (DFT) and, supported by joint experimental–theoretical calculations, protons are most easily transported in the a‐axis direction resulting in superprotonic conductivity. The present study provides a promising approach for the design of stable superprotonic conductivity materials through a simple yet effective charge‐assisted synthesis strategy. A case of iHOF (iHOF‐16) with a three‐dimensional (3D) hydrogen bonding network is reported, which exhibits excellent thermal and chemical stability. Importantly, iHOF‐16 exhibits highly anisotropic proton conductivity of 0.388, 5.56 × 10−3, and 3.25 × 10−4 S cm−1 in the direction of a‐axis, b‐axis, and c‐axis, respectively. And the proton conductivity of the powder is 2.11 × 10−2 S cm−1.