Synthesis of porous electrodes with bimodal pore size distribution to address transport limitations in next generation electrochemical reactors

In many electrochemical systems, complex single and multi-phase mass transport phenomena can occur. Often, they pose challenging to address since they are accompanied by additional restraints towards material properties such as corrosion resistance as well as electrical and thermal conductivity. Conventionally, porous structures are employed in the form of carbon fiber meshes or sintered metal particles. While sufficient to perform the task, these structures are commonly not optimized from a mass transport point of view.

Adapting these existing structures to better carry out the task required of them is ultimately always limited by their underlying structure. In this work, alternative, tailor made structures which are designed to better handle the mass transport are investigated in the form of structures with bimodal pore size distributions. An example of this form of structure is depicted in the figure below. In (a) a dynamic masking process is schematically depicted whereby dendritic coper structures are generated by the simultaneous deposition of copper from solution and gas evolution on the same surface. The resulting structure (b) displays not only a micro porous backbone but also a macro porous void structure which changes its pore size throughout the depth of the structure. Evaluating these types of materials and making them compatible with a broad range of electrochemical systems has the potential to significantly improve mass transfer and thus efficiency.