The effect of geometric configuration on fullerene and Fe tandem catalyst for ammonia synthesis

The development of efficient catalysts enabling the Haber–Bosch ammonia (NH 3 ) synthesis process under mild conditions is crucial. However, the competitive activation of co-adsorbates, that is, excessive N 2 or H 2 binding at a single active site, is detrimental to NH 3 synthesis. Herein, we demonstrate that Fe 2 O 3 mediated by fullerenes (C 60 /C 70 ) with varying geometric configurations could facilitate efficient NH 3 synthesis under mild conditions (≤400°C, ≤2 MPa). Our studies indicate that C 70 exhibits a higher curvature than C 60 , which enhances electron transfer through Fe–O–C bridges. This curvature-driven electronic modulation, combined with the spatially separated activation of N 2 (primarily on Fe sites) and H 2 (mainly on C 60 /C 70 ), synergistically enhances the dissociation of N 2 and the desorption of NH 3 . As a consequence, the developed C 70 -Fe 2 O 3 achieves an NH 3 synthesis rate of 19.10 mmol g −1 h −1 . This finding demonstrates a strategy for optimizing dual-functionality sites through selecting fullerenes with different geometric structures.