In Situ Mechanistic Study of Plasmon‐Governed Reaction Pathways in Li−O 2 Batteries With a Au@MOF Cathode

ABSTRACT Lithium–oxygen (Li–O 2 ) batteries offer a high theoretical energy density (~3600 Wh kg −1 ) but remain hindered by large recharge (RC) overpotentials, low efficiency, and limited cycle life. Integrating solar energy through localized surface plasmon resonance (LSPR) provides a sustainable route to overcome these challenges. Here, gold nanoparticles (Au NPs) were embedded into a UiO‐66‐NH 2 metal–organic framework via a one‐step “ship‐in‐a‐bottle” method without capping agents, yielding Au@UiO‐66‐NH 2 with high structural integrity, enhanced visible‐light absorption, and improved charge transport. Under illumination, the plasmon‐governed Li–O 2 battery exhibited striking morphological changes in discharge (DC) products, forming thin and film‐like lithium peroxide (Li 2 O 2 ) that decomposed more readily during RC. In Situ Fourier transform infrared spectroscopy confirmed LSPR‐driven selective Li 2 O 2 formation with suppressed lithium carbonate and carboxylate side‐products. UV‐vis, band alignment, and time‐resolved photoluminescence studies revealed efficient electron transfer from UiO‐66‐NH 2 to adjacent Au sites. Density functional theory further showed that electron‐rich Au@UiO‐66‐NH 2 interfaces lower energy barriers for both oxygen reduction and evolution reactions. The system delivered a low overpotential of 1.05 V in the first DC‐RC cycle and stable performance for over 600 h under light irradiation, with minimal Au loading (3.04 wt%). This work establishes a new benchmark for efficient, durable, and solar‐integrated Li–O 2 energy storage.