The synergy between oxidized molybdenum and covalent triazine frameworks
for electrocatalytic nitrogen fixation
Although Mo-dependent nitrogenase and synthetic molecular complexes have
attracted widespread attention in electrochemical nitrogen reduction,
the activity of Mo-based catalysts for nitrogen reduction is low.
Herein, molybdenum oxide nanoparticles were supported on
charge-modulated conjugated triazine frameworks (Mo/CTF-I) via ion
exchange reaction. Compared with Mo/CTF, the modified Mo/CTF-I maintains
high specific surface area and microporous structure after metal loading
and thermal treatment, and exposes high density MoOx as active sites.
This strong interaction between MoOx and CTF-I induces the electron
transfer from Mo to support to form MoOx with a valence state of 5+ and
lowers the energy barrier to transfer the donated electrons to the empty
anti-bonding π orbitals of N≡N. Electrochemical measurements proved that
5% Mo/CTF-I exhibited the highest NRR activity with a faradaic
efficiency of 27.3% and an NH3 yield rate of 7.23 mg h-1 gcat.-1 at
-0.405 V vs. RHE.