Overview and evaluation of crossover phenomena and mitigation measures in proton exchange membrane (PEM) electrolysis

Model-Based Investigation of Recombination Interlayers in PEM Water Electrolysis: Concentration Profiles, Efficiency, and Operational Limits

“…Generally, the oxygen crossover is far less studied because it is assumed to be less detrimental to Faradaic losses and less critical in safe operation than hydrogen crossover. 6 In addition, it is hard to measure because permeating oxygen recombines at the cathode Pt-catalyst. For this reason, there are hardly any measurements and knowledge about the oxygen crossover that can be used to parameterize and validate the proposed model.…”

“…Fahr et al provide a comprehensive review on the modeling of hydrogen crossover. 6 The transport of the dissolved gases in the water of the ionomer is only considered for the layers containing the ionomer, which are both the catalyst layers and the membrane, including the IL. In these layers, Fick's law is assumed according to Eq.…”

“…The correlations presented are merely a first attempt to describe the recombination reaction, as no model for IL exists in the literature yet. 6 The reaction of hydrogen and oxygen on Pt-catalysts has been studied extensively for many years (see e.g. [26][27][28][29][30] ).…”

“…Hence, gas crossover has to be mitigated to ensure a safe, efficient, and long-term stable operation of PEM electrolysis cells. 6 Many mitigation strategies are possible, e.g. improved membrane properties such as lower permeability, anode purging with air, or the usage of gas recombination catalysts like platinum, e.g.…”

“…A recently published paper by Fahr et al gives a comprehensive overview of crossover phenomena and mitigation measures, including ILs. 6 Despite this growing number of publications regarding the topic of ILs, there are still several open questions that are frequently discussed at conferences and also partially raised in the review by Fahr et Many of these aspects cannot be addressed solely through experiments; models are also needed to gain a better understanding, for example, resolving local effects, which experiments cannot achieve (e.g. local temperature distribution within a cell during operation).…”