LAUSR

The limited mass transfer of CO2 and the competitive hydrogen evolution reaction (HER) during photoelectrochemical (PEC) CO2 reduction usually result in low CO2 reduction activity. Here, we constructed a Cu2O/Sn/PTFE photocathode with a hydrophobic surface based on Cu2O by physical vapor deposition and a dipping method. The CO faradaic efficiency (FE) increased from 34.5% (Cu2O) to 95.1% (Cu2O/Sn/PTFE) at -0.7 V vs. RHE, and the FEH2 decreased from 27.9% (Cu2O) to 3.8% (Cu2O/Sn/PTFE). The introduction of the hydrophobic layer enhances the local CO2 concentration on the electrode surface and effectively isolates H+ from the aqueous electrolyte, thereby enhancing the CO2 reduction activity.