Crystalline Dual‐Porous Covalent Triazine Frameworks as a New Platform for Efficient Electrocatalysis

Abstract

AbstractCrystalline covalent triazine frameworks (CTFs) have gained considerable interest in energy and catalysis owing to their well‐defined nitrogen‐rich π‐conjugated porosity and superior physicochemical properties, however, suffer from very limited molecular structures. Herein we report a novel solvent‐free FeCl3‐catalyzed polymerization of 2, 6‐pyridinedicarbonitrile (DCP) to achieve the first synthesis of crystalline, dual‐porous, pyridine‐based CTF (Fe‐CTF). The FeCl3 could not only act as a highly active Lewis acid catalyst for promoting the two‐dimensional ordered polymerization of DCP monomers, but also in situ coordinate with the tridentate chelators generated between pyridine and triazine groups to yield unique Fe‐N3 single‐atom active sites in Fe‐CTF. Abundant few‐layer crystalline nanosheets (Fe‐CTF NSs) could be prepared through simple ball‐milling exfoliation of the bulk layered Fe‐CTF and exhibited remarkable electrocatalytic performance for oxygen reduction reaction (ORR) with a half‐wave potential and onset potential up to 0.902 and 1.02 V respectively, and extraordinary Zn‐air battery performance with an ultrahigh specific capacity and power density of 811 mAh g−1 and 230 mW cm−2 respectively. By combining operando X‐ray absorption spectroscopy with density functional theory calculations, we revealed a dynamic and reversible evolution of Fe‐N3 to Fe‐N2 during the electrocatalytic process, which could further accelerate the electrocatalytic reaction.