Insights into hydrophobicity‐tuned catalyst microenvironment in gas diffusion electrode for boosting CO₂ electrolysis

Abstract

CO2 electrolysis to value‐added chemicals and fuels shows tremendous potential to store renewable electricity. It features with H2O as the hydrogen source of CO2 electroreduction. Here, we aim at the effect of the hydrophobicity‐tuned catalyst microenvironment in gas diffusion electrode (GDE) on boosting CO2 electrolysis. The hydrophobic polytetrafluoroethylene (PTFE) nanoparticles are introduced in the Sn catalyst layer of GDE. The PTFE‐modified GDE compared to the non‐PTFE electrode delivers a higher HCOOH Faraday efficiency and lower overpotential at current densities of 50–250 mA cm−2. A two‐dimensional axisymmetric model jointly with electrochemical impedance spectroscopy is developed to provide mechanistic insights into the hydrophobicity regulation. The simulated polarization current densities are in keeping with experimental results. The boosted CO2 electrolysis is attributed to the decrease of the distance from the gas–liquid phase boundary to the electrocatalyst. The understanding of the catalyst microenvironment established here can be generalized to other gas‐involved electrocatalytic reactions.