Thiadiazole-based 3D covalent organic framework for efficient anhydrous proton conduction†

The design and synthesis of three-dimensional (3D) covalent organic frameworks (COFs) with exceptional stability and high proton conductivity are critical for advancing high-temperature fuel cells but remain significantly challenging. In this study, thiadiazole groups were successfully incorporated into a novel 3D COF featuring a five-fold interpenetrated diamond network through a bottom-up self-assembly strategy. The proton conduction of the thiadiazole-based 3D COF (NUST-28) under anhydrous conditions reached up to 8.40 × 10⁻² S cm⁻¹ at 120 °C after phosphoric acid doping. Furthermore, the NUST-28 conductor demonstrated good stability at constant temperature and in cyclic experiments. This work paves the way for the design and construction of 3D COFs as platforms for fast ion transportation using reticular chemistry.