Steering the Reaction Pathway of CO₂ Electroreduction by Tuning the Coordination Number of Copper Catalysts

Abstract

Cu-based catalysts are optimal for the electroreduction of CO2 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 C2+ products, while low-CN Cu favors CH4 production. For instance, over the high-CN Pot-Cu, C2+ 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 CH4, achieving the highest FECH4 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 CO2RR.

Selective CO2 electroreduction to formate over a Cu-based catalyst in S2−-containing electrolyte

“…Cu-based catalysts, especially oxide-derived Cu catalysts, have shown great performance in CO 2 electroreduction to C 2+ products due to their moderate *CO intermediate adsorption. 19–22 In contrast, sulfur doping into Cu-based catalysts has been proven to change the CO 2 RR pathway for selective formate production. 23–27 In a previous work, we developed S-doped Cu 2 O catalysts for CO 2 electroreduction to formate and have proven that a dynamic equilibrium of S exists at the Cu 2 O-electrolyte interface.…”