Overcoming Low C2+ Yield in Acidic CO2 Electroreduction: Modulating Local Hydrophobicity for Enhanced Performance

Operating electrochemical CO2 reduction reaction (CO2RR) in acidic media has garnered considerable attention due to its sustainable electrolyte cycling and stable performance. Nevertheless, the severe parasitic hydrogen evolution reaction (HER) and decayed multi-carbon species (C2+) yield still hampers efficient CO2RR in acid. Here, this work investigates the influence of local hydrophobicity on the acidic CO2RR. By employing direct electrodeposition, the hydrophobicity of the catalyst layer can be finely tuned over a wide range without additive. It is revealed that the hydrophobic microenvironment significantly suppressed HER, improved CO2RR performance and boosted C2+ yield. A Faradaic efficiency (FE) of approximate to 74% for C2+ is achieved in pH = 2 on electrodeposited copper with a highly hydrophobic environment. Moreover, this phenomenon can be extended to industrial application. An approximate to 81% total FE for the CO2RR, along with a approximate to 62% FE for C2+ species, is achieved even with commercial copper. Remarkably, the system exhibited stable operation for a continuous period exceeding 50 h at an industrially applied current density of 300 mA cm(-2). This work highlights the crucial role of interface hydrophobicity in acidic CO2RR and proposes a facile and universally applicable method for achieving efficient and stable CO2RR to high-value products in acidic media.