Switching CO 2 Electroreduction Pathways via Polyvinylpyrrolidone‐Mediated Water Configuration Control

Abstract The water configuration plays a critical role in steering the CO 2 electroreduction pathway, yet achieving precise control over water arrangement remains a significant challenge. In this study, we demonstrate that introducing trace amounts of polyvinylpyrrolidone (PVP) into 3 M KCl enables targeted control over the CO 2 electroreduction product distribution by simply adjusting the PVP concentration. Using a Cu 19 CeO x (molar ratio of Cu:Ce = 19:1) electrode, in the absence of PVP, multicarbon (C 2+ ) products dominate, but substantial CO and H 2 are also generated, with negligible CH 4 formation. Remarkably, the addition of just 25 ppm PVP shifts the primary product to CH 4 , achieving a Faradaic efficiency (FE) of 60.4% at 500 mA cm −2 . Further increasing the PVP concentration to 125 ppm switches the dominant product back to C 2+ , with an impressive FE of 90.8% at 800 mA cm −2 . This trend is consistent across various Cu‐based catalysts, highlighting the universality of this approach. Mechanistic studies reveal that PVP reconstructs the water configuration at the cathode surface, modulating not only the adsorption strength and coverage of *CO intermediates but also the kinetics of water dissociation, thereby dictating the reaction pathway.