Scalable synthesis of pyrazine-linked conjugated microporous polymers for high-performance proton conduction†

The development of high-performance proton-conducting materials with outstanding chemical/physical stability is critical for the fabrication of proton-exchange membrane fuel cells (PEMFCs), and remains a significant challenge. Herein, a one-pot in situ oxidation strategy is developed to construct a pyrazine-linked conjugated microporous polymer (HD-CMP) at the gram scale from hexahydroxy triphenylene and benzenetetramine tetrahydrochloride in the presence of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in the autoclave. The obtained HD-CMP not only exhibits extended π-conjugated structures and exceptional chemical stability under harsh conditions, but also nitrogen sites on the pyrazine functional groups could serve as binding sites for anchoring H₃PO₄ as proton carriers. Furthermore, contact angle measurements and water adsorption isotherms indicate the high water uptake capacity and hydrophilic properties of H₃PO₄@HD-CMP. Attributed to these features, the resulting H₃PO₄@HD-CMP exhibits a high proton conductivity of 1.05 × 10⁻¹ S cm⁻¹ at 80 °C under 100% RH, which can be comparable to those of most materials currently reported.