When CO2 concentrations are further reduced to the ultimate goal of atmospheric concentrations (420 ppm), optimization of the chemical environment within the porous electrode becomes vital to the performance of the carboxysome inspired system. FEM identified an optimal pH of 7.75 to offer a 2.8× improvement in fuel production over pH 7 (Figure ), with a reduced MOPS concentration of 25 mM to aid formate quantification. From the model, it was apparent that CA acts to greatly increase the current density for CO2R at atmospheric CO2 concentrations (7.8× at the optimal of pH 7.75 and 3.7× at pH 7), and that the bulk pH should be optimized to provide sufficient dissolved carbon without an overly basic pH that would reduce activity. At atmospheric concentrations, the concentration of CO2 is below that of CA, as such the steady state assumptions of the Michaelis-Menten equation may no longer be valid, however modelling of natural carboxysomes have used unmodified Michaelis-Menten kinetics. At atmospheric CO2 concentrations, effective CO2R at quantifiable rates becomes exceedingly challenging, and increased CO2 hydration kinetics become crucial to its viability. To allow for quantification, FDh loading was increased to 100 pmol and experiments were performed for increased times (48 h) on TiO2 electrodes (30 nm anatase, 12 ± 0.8 µm thickness, 0.196 cm 2 , Figure ) that give negligible background currents in constant potential electrolysis (Figure ) at the expense of poor electrochemical performance at more positive potentials >-0.45 vs SHE.