Optimizing Ru Metallene Catalytic Cathodes via Compressive Strain Engineering for an Improved Li–CO₂ Battery

Ru-based catalysts have already shown potential advantages in Li–CO 2 batteries. The strain regulation strategy has been widely used in various catalysts to achieve catalytic activity enhancement. In this study, seven different strained Ru X metallenes were systemically researched by first-principles calculations, where X = ±6, ±4, ±2, and 0%. The structure and electronic properties of Ru X 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 2 adsorption on Ru X . A linear relationship between CO 2 activation and lattice strain was demonstrated by analyzing the bond lengths, bond strengths of C–O, and bond angles of CO 2 . Specifically, under tensile strain, the CO 2 activation on Ru X was gradually improved. Among all Ru X, Ru –2 metallene with an appropriate CO 2 adsorption energy exhibited the lowest reaction energy (0.93 eV) for the rate-determining step of Li 2 CO 3 and C formation and the lowest overpotential (0.85 V), demonstrating its excellent catalytic performance in Li–CO 2 batteries. This work elucidated the electrochemical mechanism of strain regulation on Ru X metallenes as cathode catalysts for Li–CO 2 batteries and provided valuable insights for designing metal catalysts with improved catalytic activity.