From All-Triazine C₃N₃ Framework to Nitrogen-Doped Carbon Nanotubes: Efficient and Durable Trifunctional Electrocatalysts

A new all-triazine C3N3 framework was synthesized via triflic acid-mediated polymerization of 2,4,6-tricyano-1,3,5-triazine in solution, followed by ionothermal treatment in ZnCl2. Complexation of C3N3 with FeCl3, followed by reduction, gave the Fe3O4/C3N3 composite. Subsequent pyrolysis of the composite afforded the iron-species-encapsulated, nitrogen-doped carbon nanotubes, which turned out to be efficient and durable trifunctional electrocatalysts. The optimized catalyst showed a half-wave potential of the oxygen reduction reaction similar to that of platinum/carbon and higher oxygen evolution reaction activity than IrO2. The catalyst also exhibits good hydrogen evolution reaction activity.