A New Mass Transfer Diagnostic Tool for AEM CO2 Reduction
Sven Brückner a, Wen Ju a, Peter Strasser a
a The Electrochemical Energy, Catalysis, and Materials Science Laboratory, Department of Chemistry, Chemical Engineering Division, Technical University Berlin, Berlin, Germany
nanoGe Fall Meeting
Proceedings of Materials for Sustainable Development Conference (MAT-SUS) (NFM22)
#Suschem- Materials and electrochemistry for sustainable fuels and chemicals
Barcelona, Spain, 2022 October 24th - 28th
Poster, Sven Brückner, 265
Publication date: 11th July 2022

Energy demands increased over the last decades due to population growing and industrialization and according to that the CO2 emissions increased drastically. The electrochemical CO2 reduction can be a key technology for a fossil free future but for industrial applications it is necessary to analyse and understand the cathode. One of the most important things is to understand the relation between the catalyst layer structure, the mass transport and the CO2 consumption.

 

In this work we investigated two NiNC cathode GDEs for CO2 reduction to CO in a zero-gap MEA cell regarding their activity and CO2 consumption. We show that in a zero-gap MEA cell the CO2 access is more important than the active sites and introduced a new diagnostic tool. With a good mass transport regime for our catalyst, we can obtain high selectivity’s at industrial relevant currents.

 

We compared two Ni-NC catalysts with comparable activity in H-cell and noticed a different activity in the MEA. Through our modified set up we are able to measure consumption and like to introduce our new carbon crossover coefficient (CCC) which refer to the average transport ion through the membrane. This new diagnostic tool helps to identify if we have a CO2 accessibility or an active side accessibility problem.

 

In a good mass transport regime, our catalyst can reach nearly 85% FE towards CO at 300 mA cm-2 and a cell potential of 3.6 V. In addition to that, we convert 80 % of the CO2 feed which correspond to a lambda of 1.22, a single pass of 40% and a CO rich outlet stream (around 60% CO) which highlights our really active and CO selective NiNC catalyst.

 

Overall, we provide a direct method to determine the carbon consumption at the cathode and gain information of the transport ion and through- and in-plane mass transport of the GDE of an AEM zero gap CO2 electrolyzer.

The research leading to these results has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 851441, SELECTCO2.

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