Fig. 5: Influence of surfactant capping and charge on CO₂R.

a In-situ ATR-SEIRAS spectra illustrating the adsorption behavior of CTAC and CO₂ on AuNTs during electrocatalytic reactions at −1.0 V vs. RHE. b Zeta potential distributions for AuNTs capped with CTAC, PVP, and SDS. CTAC-capped AuNTs exhibit positive zeta potential, PVP-capped AuNTs show neutral potential, and SDS-capped AuNTs display negative potential. c FE_CO for AuNTs capped with different surfactants. d Migration rate of H⁺ as a function of charge density within the surfactant layer, measured at an electrode potential of −1.0 V vs. RHE, at 15 μm outside surfactant layer. The cationic surfactant layer significantly reduces the migration rate of H⁺. e pH profiles near the cathode at −1.0 V vs. RHE for different surfactant charges. A positively charged surfactant layer leads to a higher pH near the electrode surface. f Local pH at the outer Helmholtz plane (OHP) for different potentials on AuNTs catalysts covered by surfactant layers with different charge density (unit: C·cm⁻³) in H₂SO₄ (pH 1.0). The presence of a positively charged surfactant layer increases the local pH at the OHP.