Fig. 4: Further improvement strategies.

a The model predicted temperature difference (blue curve) and efficiency, including voltage efficiency (green curve) and CO Faradaic efficiency (red curve) as a function of membrane thickness under a typical current density of 200 mA cm⁻². b The effects of membrane thickness and ionic conductivity at 200 mA cm⁻². The purple dashed line indicates the peak value of energy efficiency at the corresponding thickness. c Contour plot of the salting-out current density as a function of ionic conductivity magnification and membrane thickness. The purple contour indicates the conditions required to achieve 1 A cm⁻² current density. d The model predicted temperature difference (blue curve) and efficiency, including voltage efficiency (green curve) and CO Faradaic efficiency (red curve) as a function of thermal conductivity under a typical current density of 200 mA cm⁻². e Energy efficiency as a function of thermal conductivity and membrane thickness. When the thermal conductivity was reduced by an order of magnitude compared to the reference case condition of 0.2 W m⁻¹ K⁻¹ thermal conductivity, the energy efficiency was increased from 40% to 43% under 50 μm membrane thickness. f Contour plot of the salting-out current density as a function of thermal conductivity and membrane thickness. g Techno-economic with single-variable sensitivity analysis for the CO production cost under the comparison of the reference case (blue bars) and non-isothermal 60 °C case (red bars). Source data are provided as a Source Data file.