Steering the Reaction Pathway of CO 2 Electroreduction by Tuning the Coordination Number of Copper Catalysts.

Cu-based catalysts are optimal for the electroreduction of CO 2 to generate hydrocarbon products. However, controlling product distribution remains a challenging topic. The theoretical investigations have revealed that the coordination number (CN) of Cu considerably influences the adsorption energy of *CO intermediates, thereby affecting the reaction pathway. Cu catalysts with different CNs were fabricated by reducing CuO precursors via cyclic voltammetry (Cyc-Cu), potentiostatic electrolysis (Pot-Cu), and pulsed electrolysis (Pul-Cu), respectively. High-CN Cu catalysts predominantly generate C 2+ products, while low-CN Cu favors CH 4 production. For instance, over the high-CN Pot-Cu, C 2+ is the main product, with the Faradaic efficiency (FE) reaching 82.5% and a partial current density ( j ) of 514.3 mA cm -2 . Conversely, the low-CN Pul(3)-Cu favors the production of CH 4 , achieving the highest FE CH4 value of 56.7% with a j CH4 value of 234.4 mA cm -2 . In situ X-ray absorption spectroscopy and Raman spectroscopy studies further confirm the different *CO adsorptions over Cu catalysts with different CN, thereby directing the reaction pathway of the CO 2 RR.