Boosting Energy Efficiency and Stability of Li-CO Batteries via Synergy between Ru Atom Clusters and Single-Atom Ru-N sites in the Electrocatalyst Cathode.

The Li-CO battery is a novel strategy for CO capture and energy-storage applications. However, the sluggish CO reduction and evolution reactions cause large overpotential and poor cycling performance. Herein, a new catalyst containing well-defined ruthenium (Ru) atomic clusters (Ru ) and single-atom Ru-N (Ru ) composite sites on carbon nanobox substrate (Ru @NCB) (NCB = nitrogen-doped carbon nanobox) is fabricated by utilizing the different complexation effects between the Ru cation and the amine group (NH ) on carbon quantum dots or nitrogen moieties on NCB. Systematic experimental and theoretical investigations demonstrate the vital role of electronic synergy between Ru and Ru-N in improving the electrocatalytic activity toward the CO evolution reaction (CO ER) and CO reduction reaction (CO RR). The electronic properties of the Ru-N sites are essentially modulated by the adjacent Ru species, which optimizes the interactions with key reaction intermediates thereby reducing the energy barriers in the rate-determining steps of the CO RR and CO ER. Remarkably, the Ru @NCB-based cell displays unprecedented overpotentials as low as 1.65 and 1.86 V at ultrahigh rates of 1 and 2 A g , and twofold cycling lifespan than the baselines. The findings provide a novel strategy to construct catalysts with composite active sites comprising multiple atom assemblies for high-performance metal-CO batteries.