Activation of Fe species on graphitic carbon nitride nanotubes for efficient photocatalytic ammonia synthesis

Photocatalytic ammonia synthesis, as a suitable alternative to traditional Haber-Bosch artificial nitrogen reduction process, has aroused widespread interest. Graphitic carbon nitride (g-C3N4) has emerged as an attractive metal-free photocatalyst, but its development in photocatalytic ammonia synthesis field is greatly shackled to the low photocatalytic activity. In this work, a highly active Fe-doped tubular graphitic carbon nitride (Fe-TCN) is reported, which demonstrates transformative performance on photosynthesis of NH3 from N2. Such excellent photocatalytic activity is derived from the incorporation of Fe species as the active sites to efficiently adsorb and activate N2 molecules on the surface of TCN. Simultaneously, surface-active Fe species are also regarded as the trap sites of electrons, and the concentrated electrons at surface-active Fe species can significantly improve the NH3 conversion efficiency. Impressively, Fe-TCN realized a 9.5-fold enhancement of NH3 production rate with the yield of 647 μmol g−1 h−1 (λ ≥ 420 nm), and the corresponding reaction pathways are also established.