Oxygen reduction reaction measurements on platinum electrocatalysts in gas diffusion electrode half-cells: Influence of electrode preparation, measurement protocols and common pitfalls

Impact of the Carbon Substrate for Gas Diffusion Electrodes on the Electroreduction of CO2 to Formate

“…To elucidate additional contributions to the internal resistance, a reference experiment using a silver sheet as a working electrode was performed. As a result, in accordance with literature, a constant and reproducible resistance of 0.7 Ω [39] was found for 1 M KHCO 3 (Figure S6b). This confirms the assumption of additional contributions to the internal resistance other than the iR-drop.…”

“…[38] Furthermore, a commercial, gas-fed electrolyzer setup with static electrolyte was used, which allows for a rapid and highly reproducible screening of custom-made GDEs due to the simple, but precise assembly of the cell. [39] The screening focuses on Toray Paper GDLs exclusively, given their vast coverage in literature, broad variety and good availability worldwide. Furthermore, pretests in comparison with other commercial GDLs such as SIGRACET have shown the suitability of Toray Paper for the intended study in the unsupported gas compartment of the test setup.…”

“…For the investigation, commercial SnO 2 nanoparticles were applied as a CO 2 electroreduction catalyst [38] . Furthermore, a commercial, gas‐fed electrolyzer setup with static electrolyte was used, which allows for a rapid and highly reproducible screening of custom‐made GDEs due to the simple, but precise assembly of the cell [39] . The screening focuses on Toray Paper GDLs exclusively, given their vast coverage in literature, broad variety and good availability worldwide.…”

Which insights can gas diffusion electrode half-cell experiments give into activity trends and transport phenomena of membrane electrode assemblies?

“…For GDE preparation the respective catalyst was deposited on the gas diffusion media (Sigracet 25 BC, SGL Carbon) by using a drop-casting approach, resulting in a catalyst loading of 100 μg Pt cm −2 . Detailed information on the coating technique and the measurement procedure is given in our recent publications 26,45 and in the ESI †. For the investigation of HiSPEC® 3000 catalyst and the IL modified samples, the I/C ratio was set to 0.5.…”

“…So far both variants have been utilized in GDE testing and no standard procedure exists, that was agreed on. 14,15,[24][25][26] Utilizing a solid electrolyte results in an environment that is much more complex and heterogeneous than the environment in aqueous electrolyte cells. Therefore, comparing both systems can introduce uncertainty regarding interfacial phenomena, reactant solubility, differences in local and bulk pH and transport phenomena such as removal of product water.…”