Given the high energy density and eco-friendly characteristics, lithium-carbon dioxide (Li-CO₂) batteries have been considered to be a next-generation energy technology to promote carbon neutral and space exploration. However, Li-CO₂batteries suffer from sluggish reaction kinetics, causing large overpotential and poor energy efficiency. Here, we observe enhanced reaction kinetics in aprotic Li-CO₂batteries with unconventional phase 4H/face-centered cubic (fcc) iridium (Ir) nanostructures grown on gold template. Significantly, 4H/fcc Ir exhibits superior electrochemical performance over fcc Ir in facilitating the round-trip reaction kinetics of Li⁺-mediated CO₂reduction and evolution, achieving a low charge plateau below 3.61 V and high energy efficiency of 83.8%. Ex situ/in situ studies and theoretical calculations reveal that the boosted reaction kinetics arises from the highly reversible generation of amorphous/low-crystalline discharge products on 4H/fcc Ir via the Ir-O coupling. The demonstration of flexible Li-CO₂pouch cells with 4H/fcc Ir suggests the feasibility of using unconventional phase nanomaterials in practical scenarios.

Few reports on paramagnetic metal nanoparticles with atomic precision and their difficult tailoring retard the insightful investigation of metal nanoparticle paramagnetism. Herein, we introduced a thiol-iodine mixture ligand–protecting strategy to successfully synthesize multi-shell paramagnetic [Au ₁₂₇ I ₄ (TBBT) ₄₈ (I: iodine, TBBT: 4-tert-butylphenylthiolate)]. The innermost Au atom was successfully removed via thiol induction without altering the structure framework to produce diamagnetic Au ₁₂₆ I ₄ (TBBT) ₄₈ with local ligand arrangement changed (butterfly effect), which could be further transformed into paramagnetic [Au ₁₂₆ I ₄ (TBBT) ₄₈ ] ⁺ via hydrogen peroxide oxidation. The spin populations of both paramagnetic nanoparticles are more densely distributed on surface iodine than sulfur. Diamagnetic Au ₁₂₆ I ₄ (TBBT) ₄₈ exhibited a Faradaic efficiency of ~100% at −0.57 volt during the electrocatalytic reduction of carbon dioxide to carbon monoxide, while paramagnetic Au ₁₂₇ I ₄ (TBBT) ₄₈ and [Au ₁₂₆ I ₄ (TBBT) ₄₈ ] ⁺ exhibited the maximum Faradaic efficiency of 87% at −0.67 volt and 90% at −0.57 volt, respectively, indicating the spin-catalytic activity correlation.