Synergistic regulation of hydrophobicity and basicity for copper hydroxide‐derived copper to promote the CO ₂ electroreduction reaction

Abstract A simple method was proposed to activate alkaline Cu(OH) 2 with an acidic ionomer, Nafion, to regulate its surface microenvironment, including hydrophobicity and local basicity. In particular, the direct complete neutralization reaction between Cu(OH) 2 and Nafion in aqueous solution induces the exposing of vast anions which can exclude the in‐situ‐formed hydroxides and raise the local basicity. Remarkably, the optimal Nafion‐activated Cu(OH) 2 ‐derived Cu can efficiently suppress the hydrogen evolution reaction (HER) and improve the selectivity for multi‐carbon products in the CO 2 electroreduction reaction (eCO 2 RR). The H 2 Faradaic efficiency (FE) decreased to 11% at a current density of 300 mA/cm 2 (−0.76 V vs. RHE) in a flow cell, while the bare one with H 2 had an FE of 40%. The total eCO 2 RR FE reaches as high as 83%, along with an evidently increased C 2 H 4 FE of 44% as compared with the bare one (24%), and good stability (8000 s), surpassing that of most of the reported Cu(OH) 2 ‐derived Cu. The experimental and theoretical results both show that the strong hydrophobicity and high local basicity jointly boosted the eCO 2 RR as acquired by felicitously introducing ionomer on the Cu(OH) 2 ‐derived Cu surface.