Fig. 2: Electrochemical performance evaluation under various cathode and anode temperature combinations and concept verification using a MEA-based electrolyzer.

a Linear sweep voltammetry measurement for OER with Tafel slopes shown in the inset figure for a three-electrode H-type cell consisted of IrO₂-Ti as the working electrode, platinum film as the counter electrode, and Hg/HgO as the reference electrode. b CO₂R intrinsic performance, FE_CO, and j_CO, on Ag film electrode as a function of temperature in H-type electrolyzer without iR compensation. The catalytic reaction leans toward hydrogen evolution at high temperature, thereby undermining product selectivity and CO partial current density. c Influence of temperature on ionic conductivity of anion exchange membrane (bule line) measured by four-electrode method as well as CO₂ solubility in water (red dash line⁵⁵ and solid line⁵⁶). Characteristics of electrochemical performance with CO partial current density (d) and CO Faradaic efficiency (e) in isothermal and non-isothermal operations with an Ag-NPs cathode and IrO₂-Ti anode using 1 M KOH as the anolyte for CO₂ conversion into CO. f Schematic of GDE configuration of the multi-physics model composed of a 5 μm catalyst layer (CL), a 10 μm micro porous layer (MPL), and a 300 μm gas diffusion layer (GDL). The liquid CO₂ concentration is mainly in the CL and MPL with the magnitude inversely related to temperature. g Voltage efficiency (η_V), CO Faradaic efficiency (FE_CO), and energy efficiency (η_E) as a function of current density under various isothermal and non-isothermal cases. Source data are provided as a Source Data file.