Fig. 3: Mechanistic studies.
a K+ concentration-dependent FE and C2+ current density of ER-CuNS at −1.45 VRHE. b Free energy diagrams of CO2RR-to-CO pathway on Cu (111) slab (Cu), Cu (111) slab with H2O (Cu–H2O), and Cu (111) slab with H2O and K+ species (Cu–H2O–K+) on the surface. c Reaction energy barriers of *CO dimerization on different slabs. IS, initial state. TS, transition state. FS, final state. d Integrated projected crystal orbital Hamilton population (-IpCOHP) curves of C 2p-Cu 3d bond for *OCCO intermediate adsorbed on Cu–H2O and Cu–H2O–K+ slab. e The charge density analysis of *OCCO on Cu–H2O–K+ slab according to the calculation of Bader charge. The blue, brown, red, white, and purple balls represent Cu, C, O, H, and K atoms, respectively. f CO2RR FE and C2+ current density of ER-CuNS in 0.05 M H2SO4 with 3 M alkali metal cations at −1.45 VRHE. g ECSA-normalized K+ number on F-CuNS and ER-CuNS. The inset is the operation method. h, i K+ distribution on ER-CuNS (h) and F-CuNS (i) models obtained from COMSOL Multiphysics finite-element-based simulations. All FE, current density, and K+ numbers values are means with error bars (standard deviations) from three replicates.
