Atomically Precise Cu(I) Clusters Facilitated by CeO<sub>2</sub>-Derived Reverse Hydrogen Spillover for Selective Electrochemical CO<sub>2</sub> Methanation
Jun-Kang Li, Jingjing Ma, Yu Chen, Shu‐Na Zhao, Shuyan Song, Shuang‐Quan Zang
Abstract
Atomically precise Cu clusters with stabilized low-coordinated Cu + species demonstrate promising deep CO 2 reduction capability, although product selectivity requires enhancement. To address this, two Cu clusters, [Cu 15 (PPh 3 ) 6 (PET) 13 ](BF 4 ) 2 and [Cu 18 S(PPh 3 ) 4 (PET) 16 ] (denoted as Cu 15 and Cu 18, respectively) were constructed via ligand-mediated assembly of Cu 3 triangular units. Both clusters effectively catalyze deep CO 2 reduction, with CH 4 as the dominant product (FE CH4 = 60.8 ± 1.6% at −1.4 V for Cu 15 and 50.5 ± 4.3% at −1.5 V for Cu 18 ). Notably, CeO 2 incorporation dramatically enhances CH 4 selectivity, elevating FE CH4 to 78.5 ± 0.4% at −1.3 V for Cu 15 /CeO 2 and 64.3 ± 1.9% at −1.4 V for Cu 18 /CeO 2 . In situ XAS and ex situ XPS analysis validate stabilized Cu + species within Cu clusters under CO 2 RR, favoring *CO intermediate stabilization. Kinetic analysis identifies isolated Cu sites within Cu 15 clusters as the active center for both CH 4 and C 2 H 4 formation, mediating the hydrogenation reaction via the Langmuir–Hinshelwood mechanism while suppressing C–C coupling. Theoretical calculations elucidate that CeO 2 facilitates water activation to generate abundant *H species, which subsequently migrate to sulfur sites in Cu 15 clusters through a reverse hydrogen spillover mechanism. This synergistic process significantly accelerates *CO hydrogenation kinetics, thereby enhancing the CH 4 selectivity.