Optimizing Ru Metallene Catalytic Cathodes via Compressive Strain Engineering for an Improved Li-CO Battery.

Ru-based catalysts have already shown potential advantages in Li-CO batteries. The strain regulation strategy has been widely used in various catalysts to achieve catalytic activity enhancement. In this study, seven different strained Ru metallenes were systemically researched by first-principles calculations, where = ±6, ±4, ±2, and 0%. The structure and electronic properties of Ru metallenes were investigated as well as adsorption energies of reactants, reaction thermodynamics, and electrochemical performance. The results showed that lattice expansion contributed to an upward shift in the d-band center, which enhanced the strength of the CO adsorption on Ru. A linear relationship between CO activation and lattice strain was demonstrated by analyzing the bond lengths, bond strengths of C-O, and bond angles of CO. Specifically, under tensile strain, the CO activation on Ru was gradually improved. Among all Ru, Ru metallene with an appropriate CO adsorption energy exhibited the lowest reaction energy (0.93 eV) for the rate-determining step of LiCO and C formation and the lowest overpotential (0.85 V), demonstrating its excellent catalytic performance in Li-CO batteries. This work elucidated the electrochemical mechanism of strain regulation on Ru metallenes as cathode catalysts for Li-CO batteries and provided valuable insights for designing metal catalysts with improved catalytic activity.