Tandem stepwise electrocatalytic reduction of CO ₂ to CH ₄ by monoatomic-nanocluster Cu dual active centers

Electrochemical CO₂ conversion to methane requires a multi-step hydrogenation and involves a complex cascade reaction. It would be vital to achieve efficient catalytic performance if one could construct tandem active centers towards the multiple intermediates. Herein, we provided a pyrolysis-free synthetic strategy to fabricate monoatomic-nanocluster Cu dual active centers for highly selective methanation of CO₂. Expectedly, the tandem active centers realized the stepwise electrocatalytic reduction, during which the atomic Cu increased the dissociation of H₂O while the Cu nanoclusters with a high electron density promoted the activation of CO₂, synergistically accelerating the hydrogenation of *CO into *CHO, suppressing H₂ generation and favoring the formation of CH₄. The as-prepared catalysts demonstrated a superior faradaic efficiency of 78.8% with a large partial CH₄ current density of 111.5 mA cm^-2 at -1.3 V <em>vs</em>. RHE, providing an avenue for the rational design and controllable synthesis of highly selective and active Cu-based CO₂RR catalysts.