Influence of PTFE Content in Gas Diffusion Layers Used for Gas-Phase Hydrogen Chloride Electrolysis with Oxygen Depolarized Cathode

In the present contribution, the influence of varying PTFE contents in the gas diffusion layer (GDL) on the overall performance of a polymer electrolyte membrane (PEM) electrolyzer for gas-phase hydrogen chloride electrolysis was investigated. It was found that the water management needs to be carefully adjusted to achieve an optimal performance of this new process. The GDL is one of the crucial components of the reactor influencing the water management due to the hydrophilic/hydrophobic properties. Different ex-situ characterization techniques (e.g. porosity, contact angle, water vapor adsorption) were applied to characterize GDLs with different PTFE contents. The performance during electrolysis was investigated by measuring voltage-current curves, half-cell potentials and electrochemical impedance spectroscopy. Diffusion limitations, and even more importantly, the sluggish oxygen reduction kinetics on the cathode were identified as bottlenecks of this process. Overall, a PTFE content between 20 and 30 wt% is recommended for GDLs employed in anhydrous hydrogen chloride electrolysis. (C) 2016 The Electrochemical Society. All rights reserved.