Modulating the Cu2O Photoelectrode/Electrolyte Interface with Bilayer Surfactant Simulating Cell Membranes for Boosting Photoelectrochemical CO2 Reduction

The low solubility of CO 2 molecules and the competition of the hydrogen evolution reaction (HER) in aqueous electrolytes pose significant challenges to the current photoelectrochemical (PEC) CO 2 reduction reaction. In this study, inspired by the bilayer phospholipid molecular structure of cell membranes, we developed a Cu 2 O/Sn photocathode that was modified with the bilayer surfactant DHAB for achieving high CO 2 permeability and suppressed HER. The Cu 2 O/Sn/DHAB photocathode stabilizes the *OCHO intermediate and facilitates the production of HCOOH. Our findings show that the Faradaic efficiency (FE) of HCOOH by the Cu 2 O/Sn/DHAB photoelectrode is 83.3%, significantly higher than that achieved with the Cu 2 O photoelectrode (FE HCOOH = 30.1%). Furthermore, the FE H2 produced by the Cu 2 O/Sn/DHAB photoelectrode is only 2.95% at −0.6 V vs RHE. The generation rate of HCOOH by the Cu 2 O/Sn/DHAB photoelectrode reaches 1.52 mmol·cm –2 ·h –1 ·L –1 at −0.7 V vs RHE. Our study provides a novel approach for the design of efficient photocathodes for CO 2 reduction.