Enhancing Proton Conductivity in Covalent Organic Frameworks: The Dual Role of Azole in Enriching Proton Carriers and Inducing Structural Tautomerization

ABSTRACT This study explores a novel approach to enhance proton (H + ) conduction in covalent organic frameworks (COFs), key to advancing proton exchange membrane fuel cells (PEMFCs). Traditional strategies to improve H + conductivity involve increasing carrier concentration or optimizing conduction pathways, but these approaches are often applied separately. Here, azole‐induced tautomerization is proposed as a combined strategy that both boosts H + carrier density and improves conduction via active ordering within COF pores. Specifically, loading imidazole into the pristine thiourea‐bridged COF ( COF‐S ) transformed it from an insulator into a highly conductive material, boosting its H + conductivity by 5 orders of magnitude and yielding the proton‐conducting COF‐S‐T . Spectroscopic analyses reveal greater tautomerization in COF‐S‐T than in other analogues reported in this work, with solid‐state pulsed‐field gradient nuclear magnetic resonance (PFG‐NMR) indicating a more ordered arrangement of H + carriers. Complementary density functional theory (DFT) and molecular dynamics (MD) simulations provide insight into the mechanisms, demonstrating how azole‐induced tautomerization promotes H + conduction at both microscopic and dynamic levels. This work introduces an unprecedented way for manipulating guest molecules to achieve active ordering of H + carriers, thereby significantly advancing the development of high‐performance COFs for fuel cell applications.