Facile synthesis of Fe single-atom porous photocatalysts via direct metal atomization achieving efficient photocatalytic nitrogen fixation.

• A single-atom Fe-porous g-C 3 N 4 (FPx) photocatalyst was synthesized by one-step calcination using NH 3 and HCl from NH 4 Cl as the bubble template and acidic HCl gas as the acidic gas template. • The porous structure provides more active sites and isolated Fe sites, changes the adsorption mode of N 2 from physical to chemical, and turns the photocatalytic nitrogen reduction reaction from the associative distal pathway to the associative alternating pathway. • The as-prepared samples showed excellent photocatalytic nitrogen reduction activity. 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-C 3 N 4 (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 N 2 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-C 3 N 4. This work provides new insights into photocatalytic nitrogen fixation and achieves efficient N 2 photoreduction by constructing single-atom photocatalysts. [Display omitted] [ABSTRACT FROM AUTHOR]