Dynamic Status Analysis of Porous Gas Diffusion Electrodes
Subproject (SP) 2 comprises the dynamic system analysis of macrokinetic processes on porous silver gas diffusion electrodes (GDE).
During the first funding period the processes of the oxygen reduction reaction (ORR) on silver gas diffusion electrodes were successfully characterized by dynamic experimental measurements and analyzed with a model-based approach. The generated knowledge resulted in a completely new understanding of the relevant and limiting processes and gave impulses for the improvement of the electrode design.
In the second funding period, the gained insights about reaction and transport processes on silver gas diffusion electrodes will be intensified, this time by investigating the CO2 reduction reaction (CO2RR). The ORR three-phase model will be extended and modified for the CO2RR in order to get a fundamental understanding of the interaction between current and voltage, macrokinetics, pH-value and selectivity. Simulating and analyzing specially chosen scenarios will facilitate detailed insights into the dynamic processes in the GDE under load and will make it possible to identify operating and rate limiting processes in the CO2RR. Additionally, model and simulations will be supported by dynamic electrochemical experiments coupled with concentration measurements to quantify material conversion during electrolysis and to identify relevant time constants. The given information will be used for parameterization and validation of the three-phase model. Overall, the proposed studies will be a valuable contribution to a better understanding of the mechanism and processes in the GDE and the CO2RR.
This SP will be strongly interconnected with SP1 for data comparison from dynamic modelling and simulation with the stationary electrode characterization. Moreover, there will be a strong interchange of model parameters with TP1 as well as an information transfer regarding mass transport with SP 4 & SP 5 and microkinetics with SP 6 & SP 7.