Electrochemical reduction of CO2 to CO offers a sustainable pathway to syngas for synthetic fuels and chemicals. Conducting CO2 electrolysis in pure water simplifies system design and avoids salt precipitation, yet its performance is constrained by sluggish reaction kinetics and limited selectivity. To address these challenges, we constructed a rapid-transport fixed-charge interface (RTFC-I) via electrochemical reconstruction of a polymer-modified Ag electrode, yielding a nanostructured surface coated with a quaternary ammonium polymer layer. This design creates rapid mass transport channels and a positively charged microenvironment, which stabilizes critical reaction intermediates while restricting proton transport. The optimized electrode achieves a CO Faradaic efficiency (FECO) of ∼99% at 500 mA cm-2 (25°C), and maintains 76.4% FECO at 1.0 A cm-2 (60°C). It also exhibits stable continuous operation for 1000 h, along with excellent scalability, as validated in an integrated three-cell stack featuring a total active area of 960 cm2. In situ Fourier-transform infrared (FTIR) spectroscopy, differential electrochemical mass spectrometry (DEMS), and density functional theory (DFT) calculations verify that the RTFC-I reduces the energy barrier for *COOH formation and enhances CO2 reduction activity. This work validates fixed-charge nanostructured interfaces as a robust strategy for alkaline-free CO2 electrolysis in pure water.
Wan et al. (Wed,) studied this question.