Dear Dinesh, many thanks for sharing this very interesting technical question with the RG community. In this context please have a look at the following potentially useful review article which might help you in your analysis. The challenges of this method are clearly addressed in this study:

Recent Progresses in Electrocatalysts for Water Electrolysis

Article Recent Progresses in Electrocatalysts for Water Electrolysis

The review has been published Open Access. thus it is freely available as public full text (please see attached pdf file).

Good luck with your work and best wishes!

Respected Professor Frank T. Edelmann

I am so grateful and obliged for your response. The article you provided helps me a lot for my research.

even though noble metal catalysts are the workhorses of catalysis which play a vital role in everything concerning catalysis, at the same time, like you have mentioned in the question, it is expensive. Moreover, they are not ubiquitously available unlike earth abundant metals, which leads to them being expensive, again. Also, they are toxic, and their emissions are tough to remove.

Ergo, it is preferable to use non-noble metals. The challenge is to find a non-noble-metal catalyst that can compete with noble-metal catalysts in terms of catalysis. Regulations have made it even more critical to improve the efficiency of catalysts. This makes it difficult to find a non-noble-metal catalyst because they are less effective than noble-metal catalysts. There are non-noble-metal catalysts with good potential for emission reduction, such as the CuO/CeO2 catalyst. However, the disadvantage of these catalysts is their short lifetime.

I hope this answers your question.

Dear Doctor

Go To

Current Challenges in Catalyst Development for PEM Water Electrolyzers Maximilian Bernt, Alexandra Hartig-Weiß, Mohammad Fathi Tovini, Hany A. El-Sayed, Carina Schramm, Jonas Schro¨ ter, Christian Gebauer , and Hubert A. Gasteiger

DOI: 10.1002/cite.201900101

"Conclusions

In this work, an overview of the current challenges in catalyst development for PEM-WEs is given. Due to the limited availability of iridium which is currently the only viable option as an oxygen evolution reaction (OER) catalyst, a reduction of the iridium loading from currently » 2 mgIr cm–2 to only » 0.05 mgIr cm–2, i.e., by a factor of 40 is required in order to enable a large-scale application of PEM-WEs. While the activity of current Ir-based catalysts would generally be sufficient to achieve the proposed target values for Ir loading at only minor performance losses (only 4 % increase of the cell energy consumption to produce 1 kg of H2), the development of catalyst structures with a much lower iridium packing density compared to current catalyst materials is absolutely required to realize homogeneous catalyst layers at very low Ir loadings. Several pathways to develop such high-structured catalysts (i.e., catalysts with a low iridium packing density) have been proposed in the literature. Here we show first results that demonstrate that for a high-structured catalyst a reduction of the Ir loading by a factor » 8 is possible, even with a slightly improved efficiency compared to a commercial Benchmark catalyst. With this new OER catalyst developed by Heraeus, the Ir-specific power density at an efficiency of 70%LHV (≡ 1.79 V) of » 0.05 gIr kW–1 can be achieved at > 3 A cm–2 with a 50 mm thick Nafion membrane. To make the development of new catalyst materials more efficient, activity and durability screening methods are required to allow a fast identification of promising materials. The rotating disk electrode (RDE) method which is commonly used to evaluate catalyst performance is shown to be suitable for a characterization of catalyst activity, while OER catalyst stability tests are affected by measurement artefacts and, hence, do not give meaningful information about catalyst lifetime. Consequently, accelerated stress tests (AST) on the membrane electrode assembly (MEA) level are required to evaluate catalyst stability at realistic operating conditions. A test protocol simulating an intermittent power supply by cycling between open circuit voltage (OCV) and operating potentials is presented as an example for such an AST. Here, the recurring transition between reducing and oxidizing conditions leads to the dissolution of Ir and the formation of a contact resistance between electrode and PTL resulting in a much higher degradation rate compared to a reference experiment without OCV periods. The information gained from this experiment helps to identify harmful operating conditions that need to be avoided in real PEM-WE systems."