Highly Selective Electrocatalytic CO 2 Conversion to Tailored Products through Precise Regulation of Hydrogenation and C-C Coupling.

The electrochemical reduction reaction of carbon dioxide (CO 2 RR) into valuable products offers notable economic benefits and contributes to environmental sustainability. However, precisely controlling the reaction pathways and selectively converting key intermediates pose considerable challenges. In this study, our theoretical calculations reveal that the active sites with different states of copper atoms (1-3-5-7-9) play a pivotal role in the adsorption behavior of the *CHO critical intermediate. This behavior dictates the subsequent hydrogenation and coupling steps, ultimately influencing the formation of the desired products. Consequently, we designed two model electrocatalysts comprising Cu single atoms and particles supported on CeO 2 . This design enables controlled *CHO intermediate transformation through either hydrogenation with *H or coupling with *CO, leading to a highly selective CO 2 RR. Notably, our selective control strategy tunes the Faradaic efficiency from 61.1% for ethylene (C 2 H 4 ) to 61.2% for methane (CH 4 ). Additionally, the catalyst demonstrated a high current density and remarkable stability, exceeding 500 h of operation. This work not only provides efficient catalysts for selective CO 2 RR but also offers valuable insights into tailoring surface chemistry and designing catalysts for precise control over catalytic processes to achieve targeted product generation in CO 2 RR technology.