Non-invasive current collectors for improved current-density distribution during CO2 electrolysis on super-hydrophobic electrodes

Abstract

Abstract Electrochemical reduction of CO2 presents an attractive way to store renewable energy in chemical bonds in a potentially carbon-neutral way. However, current electrolyzers suffer from intrinsic problems, like flooding and salt accumulation, that must be overcome to industrialize the technology. To resolve flooding and salt precipitation issues, researchers have used ultra-hydrophobic electrodes based on either polytetrafluoroethylene (PTFE) gas-diffusion layers (GDL’s), or carbon-based GDL’s with added PTFE. While the PTFE backbone is highly-resistant to flooding, the non-conductive nature of PTFE means that without additional current collection the catalyst layer itself is responsible for electron-dispersion, which penalizes system efficiency and stability. In this work, we present operando results that illustrate the poor current/potential distribution in thin catalyst layers (~50 nm) deposited onto PTFE GDL’s. We then compare the effects of thicker catalyst layers (~500 nm) and a newly developed non-interfering current collector (NICC). The NICC can maintain even current distribution with 10-fold thinner catalyst layers while improving stability towards ethylene (≥ 30%) by approximately two-fold.