Hydrophobic surface efficiently boosting Cu 2 O nanowires photoelectrochemical CO 2 reduction activity.

The limited mass transfer of CO 2 and the competitive hydrogen evolution reaction (HER) during photoelectrochemical (PEC) CO 2 reduction usually result in low CO 2 reduction activity. Here, we constructed a Cu 2 O/Sn/PTFE photocathode with a hydrophobic surface based on Cu 2 O by physical vapor deposition and a dipping method. The CO faradaic efficiency (FE) increased from 34.5% (Cu 2 O) to 95.1% (Cu 2 O/Sn/PTFE) at -0.7 V vs. RHE, and the FE H2 decreased from 27.9% (Cu 2 O) to 3.8% (Cu 2 O/Sn/PTFE). The introduction of the hydrophobic layer enhances the local CO 2 concentration on the electrode surface and effectively isolates H + from the aqueous electrolyte, thereby enhancing the CO 2 reduction activity.