Synthesis of Bimetallic Co–Ni Co‐Doped g‐C ₃ N ₄ and Its Photocatalytic Performance for Nitrogen Fixation Under Visible Light

ABSTRACT Bimetallic Co–Ni co‐doped carbon nitride catalysts (CoNi‐CN) were prepared by a simple one‐step thermal condensation method and used for photocatalytic nitrogen fixation. The obtained catalysts were analyzed by various characterization methods and DFT simulations. The results show that the metal is doped in the interstitial position by forming metal‐N coordination bonds. Compared with mono‐metal Ni‐doped g‐C 3 N 4 (graphite carbon nitride), the addition of cobalt reduces the band gap energy and improves the electron–hole separation efficiency. In addition, the introduction of cobalt promotes the activation of nitrogen molecules and accelerates the transfer of electrons from the catalyst to the activated nitrogen molecules through the “Ni–Co–N bridge”. The NH 4 + formation rate of CoNi‐CN is 1.8 mg·L −1 ·h −1 ·g cat −1 , which is 4.5 and 1.5 times higher than that of neat and mono Ni‐doped g‐C 3 N 4 . This study provides a simple and effective catalyst preparation method for nitrogen photofixation.