Light-Induced Variation of Lithium Coordination Environment in g-C₃N₄ Nanosheet for Highly Efficient Oxygen Reduction Reactions

The structure and electronic state of the active center in a single-atom catalyst undergo noticeable changes during a dynamic catalytic process. The metal atom active center is not well demonstrated in a dynamic manner. This study demonstrated that Li metal atoms, serving as active centers, can migrate on a C₃N₄ monolayer or between C₃N₄ monolayers when exposed to light irradiation. This migration alters the local coordination environment of Li in the C₃N₄ nanosheets, leading to a significant enhancement in photocatalytic activity. The photocatalytic H₂O₂ process could be maintained for 35 h with a 920 mmol/g record-high yield, corresponding to a 0.4% H₂O₂ concentration, which is far greater than the value (0.1%) of practical application for wastewater treatment. Density functional theory calculations indicated that dynamic Li-coordinated structures contributed to the superhigh photocatalytic activity.