Amorphous Fe2CoOx cocatalysts enable efficient photocatalytic nitrogen reduction reaction: Synergistic nitrogen activation, charge separation and reaction pathway modulation.

Developing high-performance photocatalytic systems for nitrogen fixation is a crucial yet challenging for sustainable ammonia synthesis. Herein, an amorphous Fe2CoOx cocatalyst is successfully loaded onto Bi2MoO6 (BMO) to construct a highly efficient photocatalytic nitrogen reduction reaction (NRR) system. Visible-light-driven ammonia production over the optimized 1.0Fe2CoOx/BMO composite reaches 860.7 μmol g-1 h-1, about 15.4 times that of pristine BMO, outperforming most reported photocatalysts. The results of comprehensive characterizations and density functional theory calculations demonstrate that the amorphous Fe2CoOx cocatalyst not only rapidly captures photogenerated electrons and suppresses charge recombination, but also provides abundant Fe sites as dominant active centers that boost N2 adsorption and activation. More importantly, the introduction of Fe2CoOx unlocks the previously kinetically blocked distal pathway in addition to the intrinsic alternating pathway, thereby broadening the reaction pathways and significantly accelerating the overall NRR kinetics. In addition, the universal performance enhancement capability of this amorphous cocatalyst is verified on multiple representative photocatalysts, including ZnIn2S4, Bi2WO6, TiO2 and g-C3N4. This work demonstrates that engineering amorphous bimetallic oxide cocatalysts is an effective strategy for developing highly efficient photocatalytic NRR systems.