Fig. 6: Post CO₂R, in-situ measurements and reaction kinetics analysis.

a water contact angle for the five polymer/Cu GDEs after CO₂R at −0.5 A cm⁻². b in-situ XAS measurements. c CO₂R performance of C₂₊ selectivity and cathodic potentials on the function of CO₂ partial pressure at −0.5 A cm⁻², and d the influence of the local H₂O/CO₂ ratio (regulated by changing the CO₂ partial pressure) on CO₂R performances under identical cathodic potentials. The CO₂ partial pressure was adjusted by mixing CO₂ with Ar. A 50% CO₂ partial pressure correlates to a doubled H₂O/CO₂ ratio than that of 100% CO₂ concentration. e Nyquist plots of electrochemical impedance spectroscopy at −0.38 V vs. RHE in flow cell, the inset shows the equivalent circuit used for the curve fitting. The symbols in this figure are original data, the solid lines are fitting data. f Tafel plots for the CO₂R to C₂₊ products for PT/Cu, PCR/Cu, PT95/Cu, PVDF/Cu and Nafion/Cu GDEs. The average equilibrium potential from CO₂R to C₂₊ products was deemed as 0.09 V vs. RHE. All the CO₂R tests here were conducted in a flow cell, and the electrolyte is 2 M KOH. For panels c, d and f, 100% iR correction was applied. Details regarding the iR correction can be found in the Method section. For the overpotential calculation in panel f, the average equilibrium potential for C₂₊ products were set as 0.09 V. The error bars in panel c and d represent standard deviations from at least three independent measurements. Relevant source data are provided as a Source Data file.