Tuning electronic and composition effects in ruthenium-copper alloy nanoparticles anchored on carbon nanofibers for rechargeable Li-CO₂ batteries

Rechargeable Li-CO₂ batteries are attracting increasing attention due to their high energy density and ability to capture greenhouse gas CO₂. However, the difficulty in decomposing electronically insulating and electrochemically sluggish Li₂CO₃ discharge products under low charge voltages is still a major challenge. Herein, for the first time, a composite of intermixed ruthenium-copper alloy nanoparticles uniformly anchored on carbon nanofibers (i-RuCu/CNFs) as efficient cathode electrocatalysts for Li-CO₂ batteries is well designed. Remarkably, the Li-CO₂ batteries with i-Ru₄Cu₁/CNFs cathodes can be steadily cycled for over 110 cycles without capacity decay. And they show record-high rate capability along with much decreased overpotentials of 1.45 and 1.56 V even at current densities of 1000 and 2000 mA g⁻¹, respectively. Moreover, a high discharge capacity of 15,753 mAh g⁻¹ is obtained for Li-CO₂ batteries based on i-Ru₄Cu₁/CNFs, and 99.3% of discharged capacity could be reversibly charged, giving the significant Coulombic efficiency. This work demonstrates the powerfully catalytic activity of intermixed RuCu nanoalloys for easily decomposing discharge products in Li-CO₂ batteries and provides more insights to design more highly efficient cathode electrocatalysts for Li-CO₂ batteries and beyond.