Shaping the electric field: overcoming geometric inhomogeneities in the electrochemical fabrication of mesoporous materials

Journal
ACS applied engineering materials
Citation
Applied Engineering Materials (in Press): (2026)
Publisher DOI
10.1021/acsaenm.6c01020
Publisher
ACS Publications
Is Supplemented By
10.15480/882.18502
Integrating porous systems such as mesoporous silicon (pSi) into reliable macroscopic devices for sensing, photonics and energy storage requires stringent control over their structural homogeneity. While radial variations in layer thickness and porosity are frequently attributed to edge sealing effects or pinned gas, the macroscopic impact of the electrochemical cell’s internal geometry is largely overlooked. Using pSi as a model system, we demonstrate that the insulating cell body acts as a significant field-shaping component. Combining 2D axisymmetric finite element simulations of the current distribution with spatially resolved near-infrared (NIR) spectrometry, we investigate distortions caused by standard cell features. We reveal that the internal container widening step, commonly used to accommodate counter electrodes, strongly compresses the electric field and generates localized, ring-shaped zones of accelerated etching. Optimizing this step height reduced the radial thickness deviation of a pSi layer 6-fold to just 2%. Furthermore, predictive simulations demonstrate that internal obstacles, such as stirring rods, can be deliberately positioned to either prevent unwanted current shadows or actively manipulate the current distribution for precise three-dimensional structuring. Ultimately, mindful hardware design that prioritizes spatial current distribution is a critical and efficient strategy to maximize the yield of highly homogeneous porous media, directly enhancing their scalability and performance in functional nanomaterial applications.
DDC Class
620: Engineering