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

The low solubility of CO2 molecules and the competition of the hydrogen evolution reaction (HER) in aqueous electrolytes pose significant challenges to the current photoelectrochemical (PEC) CO2 reduction reaction. In this study, inspired by the bilayer phospholipid molecular structure of cell membranes, we developed a Cu2O/Sn photocathode that was modified with the bilayer surfactant DHAB for achieving high CO2 permeability and suppressed HER. The Cu2O/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 Cu2O/Sn/DHAB photoelectrode is 83.3%, significantly higher than that achieved with the Cu2O photoelectrode (FEHCOOH = 30.1%). Furthermore, the FEH2 produced by the Cu2O/Sn/DHAB photoelectrode is only 2.95% at -0.6 V vs RHE. The generation rate of HCOOH by the Cu2O/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 CO2 reduction.