Abstract: Photocatalytic nitrogen fixation has been explored as a feasible pathway for ammonia synthesis. However, the convenient and efficient preparation of photocatalysts for nitrogen fixation remains a challenge. Meanwhile, the reaction pathway and mechanism of photocatalytic nitrogen fixation are unclear. Herein, single-atom Fe-porous g-C₃N₄ (FPx) samples were manufactured using a one-step anneal technique via bubble template and direct metal atomization. Characterization results indicate that FPx has a porous structure and single-atom Fe. The porous structure exposed more active centers. Simultaneously, single-atom Fe changes the adsorption mode of N₂ from physical to chemical and turns the photocatalytic nitrogen fixation from the associative distal pathway to the associative alternating pathway. Consequently, without any sacrificial agent or cocatalysts, FPx presents a prominent increase in photocatalytic activity, reaching 62.42 µmol h^-1 g^-1, over fivefold larger than that of bulk g-C₃N₄. This work provides new insights into photocatalytic nitrogen fixation and achieves efficient N₂ photoreduction by constructing single-atom photocatalysts.

Key words: Single-atom Fe, Porous, Graphitic carbon nitride, Photocatalytic nitrogen fixation