Axiomatic Design for Analysis and Noniterative Engineering of Photoelectrochemical Cells for CO₂ Conversion at High...

An Axiomatic Design (AD) theoretical protocol is proposed for the analysis and noniterative engineering of photoelectrochemical (PEC) cells that can convert CO₂ toward C₂₊ products. AD provides criteria for identifying and selecting materials based on data commonly available in the literature. In addition, it establishes a design order for how to achieve optimal integration of materials for catalysis and light-induced charge separation with a proton-transporting membrane in a noniterative manner by matching relevant fluxes with concentration at interfaces across the design. For a hypothetical tandem PEC flow cell reactor for ethylene as an example, the AD protocol predicts an upper bound of 31 μmol h^-1 cm^-2 at 12% solar-to-product efficiency following PEC process optimization with a design path comprising five steps, starting from data for an O-(II)-D-Cu CO₂ reduction reaction (CO₂RR) catalyst and including current concentration to tailor the overpotential. The computational procedure provides models with high yield and robustness by balancing high selectivity with low overpotential and a broad operation range of 0.5-1.2 Sun with a dual absorber with bandgaps of 1.90 and 1.35 eV and a fill factor of 0.85. The procedures are implemented in Python and use a decoupled design matrix that eliminates interdependencies between components.