Atomically-Scattered Active Centers Accelerating Photocatalytic Evolution of Ammonia

Photocatalytic N2 reduction to ammonia rises as a cost-effective, environmentally benign, and efficient route to generate ammonia as a transportable/storable energy carrier and essential fertilizer. Recently, photocatalysts anchored with various atomically scattered active centers (ASACs), such as Ru, Fe, Au, Pt, Cu, Mo, and La, are extensively explored in photocatalytic N2-to-ammonia transformation. This review critically summarizes the current achievements in the synthesis of various photocatalyst supports (such as metal oxide, carbon nitride, metal-organic framework, and covalent organic framework) anchored with the above-mentioned ASACs for N2 reduction to form ammonia. The synthesis routes, structural/compositional characteristics, and performances of these ASACs anchored photocatalysts are summarized and introduced. Furthermore, the atomic-scale relationship between the structure/composition and performance of these ASACs anchored photocatalysts is also introduced. The reaction mechanism including the reaction kinetics/thermodynamics, reaction pathways, and charge carrier kinetics, especially those revealed by various state-of-art characterization techniques, have been highlighted. This review also outlines the basic principles for the synthesis of novel photocatalysts aimed at ammonia evolution. Finally, the current challenges, opportunities, and future outlooks of ASACs anchored photocatalysts for ammonia evolution are introduced. This review introduces the current achievements of atomically scattered active centers (ASACs) anchored photocatalysts for N2 reduction to ammonia. The synthesis technique, structure/composition, structure-activity correlation, and reaction mechanism of these ASACs anchored photocatalysts are carefully summarized. And the challenges and future outlooks in this area are introduced at last. image