Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Covalent triazine frameworks (CTFs) are among the most valuable
frameworks owing to many fantastic properties. However, molten
salt-involved preparation of CTFs at 400–600 °C causes debate on whether
CTFs represent organic frameworks or carbon. Herein, new CTFs based on the
1,3-dicyanoazulene monomer (CTF-Azs) are synthesized using molten ZnCl2
at 400–600 °C. Chemical structure analysis reveals that the CTF-Az prepared at
low temperature (400 °C) exhibits polymeric features, whereas those prepared
at high temperatures (600 °C) exhibit typical carbon features. Even after being
treated at even higher temperatures, the CTF-Azs retain their rich porosity, but
the polymeric features vanish. Although structural de-conformation is a widely
accepted outcome in polymer-to-carbon rearrangement processes, the study
evaluates such processes in the context of CTF systems. A proof-of-concept
study is performed, observing that the as-synthesized CTF-Azs exhibit
promising performance as cathodes for Li- and K-ion batteries. Moreover, the
as-prepared NPCs exhibit excellent catalytic oxygen reduction reaction (ORR)
performance; hence, they can be used as air cathodes in Zn-air batteries. This
study not only provides new building blocks for novel CTFs with controllable
polymer/carbon features but also offers insights into the formation and
structure transformation history of CTFs during thermal treatment.