In Situ Observation of the pH Gradient near the Gas Diffusion Electrode of CO2 Reduction in Alkaline Electrolyte

• DOI: 10.1021/jacs.0c06779
• Publication Date: 2020-07-21T21:49:13Z
• Authors: Xu Lu; Chongqin Zhu; Zishan Wu; Jin Xuan; Joseph S. Francisco; Hailiang Wang
• Keywords: Overpotential; Gas diffusion electrode; Diffusion layer; Supporting electrolyte

The local pH variation near the surface of CO2 reduction electrodes is important but hard to study. We develop a continuous-flow Raman electrochemical cell that enables first experimental study gas diffusion electrode under reaction conditions. At zero current, chemically reacts with 1 M KOH electrolyte at interface form HCO3- and CO32-. on cathode 7.2, concentration profile extends distance 120 μm into electrolyte, which verifies nominal overpotential from using alkaline originates Nernst potential gradient layer cathode/electrolyte interface. CO2-OH- neutralization still persist, albeit reduced extent, current densities up 150 mA/cm2.