Molecular fluid transport and distribution in porous electrodes for CO2 electrolysis

Electrochemical CO2 conversion into useful chemicals holds great promise to mitigate climate change. This electrochemical process requires the catalyst to be in contact with water, but the water at the same time hinders rapid transport of CO2 to the catalyst surface, due to the low CO2 solubility and diffusivity in water. So-called gas diffusion electrodes largely overcome this issue by supplying CO2 gas directly to the vicinity of the catalyst particles through a dedicated gas transport medium. However, the pores in this medium tend to flood with water, once again hindering gas transport.

Designing gas diffusion electrodes and the operating conditions of the conversion process in such a way that avoids flooding, requires detailed insight into the distribution of liquid and gas components within the porous structure, and how this distribution affects fluid transport in the pores. Such local insight within a porous electrode is experimentally inaccessible, whereas it can be obtained through simulations. This project focused on gaining molecular-level insight into the local reaction environment near the catalytic material within a porous electrode. Using cutting-edge molecular dynamics simulations, supported with experiments, we study the distribution of components across the electrical double layer at the electrode-electrolyte interface. Insight into local concentrations and the local electric field is importat as they largely determine reaction kinetics. Additionally, to gain insight into the distribution of fluid throughout the gas diffision electrode, we also investigate how surface wetting is affected by an applied electrode potential (electrowetting).

This project is coupled to another PhD project in which the fluid distribution throughout the porous electrode will be simulated on a larger scale, using input from this project. Both projects are part of an NWO Vidi grant, which has as a goal to find how to modify gas diffusion electrodes such that flooding is avoided, and performance is improved.

Chair:
Complex Fluid Processing

Involved People:
Dr. Remco Hartkamp 
Prof. Johan Padding
Ir. Fathaah Ansar