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Effective electrochemical conversion of CO2 to value-added liquid multi-carbon products driven by renewable energy is a promising approach to alleviate excessive CO2 emission and achieve large-scale renewable energy storage. However, the selectivity and catalytic activity towards liquid multi-carbon products of CO2 electroreduction reaction are still unsatisfactory due to the sluggish C–C coupling process and the formation of complex oxygen-containing intermediates. Hence, designing and fabricating highly effective electrocatalysts is crucial for practical applications in this field. Here, we developed Cl-modified Cu catalyst (Cu-Cl) for efficient electrochemical reduction of CO2 to ethanol. The optimal Faradaic efficiency and partial current density of ethanol on the Cu-Cl sample reached 26.2% and 343.2 mA·cm−2 at −0.74 V (vs. reversible hydrogen electrode (RHE)), which were 1.66 and 1.76 times higher than those of the catalyst without Cl decoration, outperforming those in most previously reported works. Density functional theory (DFT) calculations revealed that the Cl-modified Cu surface suppressed the parasitic hydrogen evolution reaction (HER) and reduced the energy barrier for the C–C coupling process, making the formation of key intermediates favorable for ethanol production. Thus, the decoration of Cl on the Cu surface facilitated ethanol formation. [ABSTRACT FROM AUTHOR]

The electrocatalytic reduction of CO2 presents a promising strategy in addressing environmental and energy crisis. Significant progress has been achieved via CO2 gas diffusion electrolysis, to react at high selectivity and high rate. However, the gas diffusion layer (GDL) of the gas diffusion electrode (GDE) still suffers from low tolerance and limited active sites. Here, the hydrophobic 1-octadecanethiol molecular was functionalized over the Cu catalyst layer of the GDE, which simultaneously stabilizes the GDL and exposes abundant active solid-liquid-gas three-phase interfaces. The resultant GDE exhibits multi-carbon (C2+) product selectivity over faradaic efficiency (FE) of 70.0% in the range of 100 to 800 mA·cm−2, with the peak FEC2+ of 85.2% at 800 mA·cm−2. Notably, the strengthened GDE could continuously drive high-current electrolysis for more than 100 h without flooding. This work opens a new way to improve CO2 gas diffusion electrolysis via surface molecular engineering. [ABSTRACT FROM AUTHOR]