Size-Dependent Effects of Ru Nanoparticles on Li-CO<sub>2</sub> Batteries

Li-CO<sub>2</sub> batteries capture and convert CO<sub>2</sub> into\na valuable energy storage medium, promoting both energy storage and\nenvironmental sustainability. While Ru-based catalysts exhibit exceptional\ncatalytic activity and are widely deployed in Li-CO<sub>2</sub> batteries,\nthe Ru nanoparticle size effects on electrolysis remains underexplored.\nHerein, we synthesized Ru nanoparticles ranging from ∼1.1 to\n∼7.4 nm to unveil the size-dependent activity in Li-CO<sub>2</sub> batteries. As Ru size decreases, the d-band center of Ru\nis identified upshifted toward the Fermi level, and the Gibbs energy\nchange for the rate-determining step during charge is lowered. The\nbinding energy of CO and Li–O is notably reduced, confirming\nthat a strong interaction between small Ru and Li<sub>2</sub>CO<sub>3</sub> can destabilize Li<sub>2</sub>CO<sub>3</sub> and facilitate\nits decomposition. Furthermore, small Ru nanoparticles can alleviate\n Li<sub>2</sub>CO<sub>3</sub> accumulation on cathodes. This work\nprovides insight and guidance for catalyst design and optimization\nin Li-CO<sub>2</sub> batteries, which can be extended to other battery\nsystems involving solid product formation and decomposition.