Remove the innermost atom of a magnetic multi-shell gold nanoparticle for near-unity conversion of CO ₂ to CO

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 [Au₁₂₇I₄(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 Au₁₂₆I₄(TBBT)₄₈ with local ligand arrangement changed (butterfly effect), which could be further transformed into paramagnetic [Au₁₂₆I₄(TBBT)₄₈]⁺ via hydrogen peroxide oxidation. The spin populations of both paramagnetic nanoparticles are more densely distributed on surface iodine than sulfur. Diamagnetic Au₁₂₆I₄(TBBT)₄₈ exhibited a Faradaic efficiency of ~100% at -0.57 volt during the electrocatalytic reduction of carbon dioxide to carbon monoxide, while paramagnetic Au₁₂₇I₄(TBBT)₄₈ and [Au₁₂₆I₄(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.