Tandem catalysis involves two or more catalysts arranged in proximity within a single reaction vessel, with the aim of synergistically aligning the catalysts' reaction pathways to maximize overall system performance. This study presents a proof of concept showing the integration of continuum transport modeling with design optimization in a simplified two-dimensional flow reactor setup for electrochemical CO2 reduction. Ag catalysts provide the CO2→ CO reaction capability, and Cu catalysts provide the CO → high-value products reaction capability. Given a set of input parameters, the optimization algorithm uses adjoint methods to modify the Ag/Cu surface patterning in order to maximize the current density toward high-value products, such as ethylene. The optimized designs yield significant performance enhancement especially at more negative applied voltages (i.e., stronger surface reactions) and for larger numbers of patterning sections. For an applied voltage of −1.7 V vs. SHE, the 12-section optimized design increases the current density towards ethylene by up to 65% compared to the unoptimized 2-section design. For the optimized cases, observed differences in the production and consumption of CO (the key intermediate species) and minimized zones of low CO reactant surface concentration on Cu sections explain the improved reactor performance.
@article{arxiv.2511.07638,
title = {Optimized tandem catalyst patterning for CO$_2$ reduction flow reactors},
author = {Jack Guo and Thomas Roy and Nitish Govindarajan and Joel B. Varley and Jonathan Raisin and Jinyoung Lee and Ji-Wook Jang and Dong Un Lee and Thomas F. Jaramillo and Tiras Y. Lin},
journal= {arXiv preprint arXiv:2511.07638},
year = {2026}
}