Interplay of [C₆₀]Fullerene and Cu₂O Nanocrystals for Stable CO₂ Electroreductionto C₂₊ Products

Abstract

Copper oxides such as Cu₂O are promising catalysts for the electrochemical CO₂ reduction reaction (CO₂RR) to C₂₊ products, yet their intrinsic susceptibility to Cu⁺ reduction and morphology degradation severely limits their long-term performance. Herein, we report a facile two-step wet-chemical route to interface [C₆₀]fullerene with cubic Cu₂O (c-Cu₂O), octahedral (o-Cu₂O), and dodecahedral (d-Cu₂O) crystals. The resulting composite optimal c-Cu₂O–C₆₀ achieves substantial Faradaic efficiencies of 60.4% in an H-cell and 65.6% in a flow-cell for C₂₊ products, which is 3-fold higher than pristine c-Cu₂O, while maintaining stable operation for 100 h at –1.2 V versus RHE without detectable activity loss. Our experimental results and theoretical study demonstrate that the strategic incorporation of C₆₀ during the synthesis of Cu₂O directly endows the surfaces of the resultant Cu₂O crystals with abundant Cu⁺/Cu⁰ grain boundaries. Additionally, the presence of C₆₀ induces the formation of more Cu⁺/Cu⁰ boundaries during the CO₂RR process, which synergistically facilitate the generation of C₂₊ products. Moreover, C₆₀ acts as an electron buffer, preventing Cu⁺ from being over-reduced during the reduction process, thereby sustaining active Cu⁺/Cu⁰ interfaces and maintaining the catalytic activity for C₂₊ products. Extension to hydroxylated and fluorinated fullerene derivatives delivers comparable C₂₊ selectivity, underscoring the generality of this fullerene-mediated stabilization strategy for designing robust Cu-based CO₂RR catalysts.