Adaptation of a PEMFC Reference Electrode to PEMWE: Possibilities and Limitations

Abstract

This work presents a platinum wire micro-reference electrode suitable for recording in-operando individual electrochemical impedance spectra of both the anode and the cathode in a proton exchange membrane water electrolyzer. The setup enables the protonic membrane potential to be accessed outside the active area. The reference electrode allows for the analysis of kinetic parameters for anode and cathode reactions separately. However, the exact location of the measured membrane potential is unknown due to a potentially asymmetric potential distribution, which makes the calculation of exact kinetic parameters non-trivial. Qualitative analyses of the potential distribution behavior over temperature, cell compression, and current density are shown.

Review—Reference Electrodes in Proton Exchange Membrane Water Electrolysis: Previous Approaches, Current Application, and Perspectives

“…Nafion™'s proton concentration (c H+ ) is not exactly determined as discussed in a recent work. 34 External RE.-An external RE is characterized by a stable and precisely defined electrochemical potential. In the context of this study, it pertains to a system, often commercially available, designed for use in electrochemical cells.…”

“…10 and 11, polarization curves are constructed, elucidating the measurable half- Figure 8. RE configuration outside the active area at the membrane (a) setup with a membrane strip and external RE, 58 (b) set up with single wire RE, as designed in recent work by this group, 34 (c) electronic and protonic potential distribution with a typical 5-layer PEM water electrolysis cell, indication of potential measurements. cell potentials in Fig.…”

“…58 Abdelrahman et al also used a membrane strip for PEMWE but used a RHE with an external H 2 feed. 84 Furthermore, finally, recent work from this group took a system from FC research and adopted a PEMWE cell to measure the stability and the limitations of the RE 34 and carry out a degradation study. 85 This retrospective analysis of previous implementations demonstrates the versatility of the setup, which can be realized in various configurations.…”

“…Previous studies have addressed this by implementing platinization of the wire or adding an extra platinum catalyst patch on the membrane. 34 When opting for a DHE, cathodic polarization of the Pt wire is necessary, leading to specific setup requirements. Hydrogen generation at the wire may result in a slight polarization of the wire.…”

“…External hydrogen feed systems necessitate humidified hydrogen streams, allowing precise control over parameters such as temperature and humidification. 34 In the case of an external RE, establishing contact with a liquid electrolyte is essential. This involves selecting an appropriate acidic solution and concentration; historically, 0.5 M H 2 SO 4 solutions have been utilized.…”