Fe3+ doping promoted N2 photofixation ability of honeycombed graphitic carbon nitride: The experimental and density functional theory simulation analysis.

Honeycombed iron doped graphitic carbon nitride with outstanding N 2 photofixation ability is synthesized in this work. Characterization results indicate that Fe 3+ inserts at the interstitial position and is stabilized in the electron-rich g-C 3 N 4 through the coordinative Fe-N bonds. Fe 3+ sites can chemisorb and activate N 2 molecules, then transfer the photogenerated electrons from the g-C 3 N 4 to adsorbed N 2 molecules. Fe0.05-CN displays the highest NH 4 + generation rate, which is approximately 13.5-fold higher than that of neat g-C 3 N 4 . Density functional theory simulations prove the N 2 activation effect of Fe 3+ sites due to the high adsorption energy and prolonged N N bond. Charge density difference result confirms the electrons transfer process from the Fe 3+ doping sites to N 2 molecule. DOS results indicate that the electrons of σ g 2p orbital (HOMO) in nitrogen atom is delocalized significantly when N 2 adsorbed on Fe 3+ doping sites, leading to its orbital energy almost connects to that of π g * 2p orbital (LUMO), which confirming that Fe 3+ doping sites can activate the N 2 molecule effectively. The Mulliken charge of nitrogen is −3.1 when the N 2 adsorbed on Fe 3+ doping sites, indicating that N 2 molecule is enriched by large number of electrons, which is beneficial to the H + attack to form NH 4 + . [ABSTRACT FROM AUTHOR]