Fig. 4: Performance of Sn₂/NCB in NO₃RR and mechanisms.

a LSV curves of Sn₂/NCB with and without NO₃⁻, Sn₁/NCB with NO₃⁻, and NCB with NO₃⁻. The voltages were not iR corrected. b NO₃⁻ conversion rates and N₂ selectivity of Sn₂/NCB, Sn₁/NCB, and NCB. c NO₃⁻ conversion rates and N₂ selectivity of Sn₂/NCB under varied potentials. The voltages were not iR corrected (electrode surface area = 1 cm², resistance value = 3 Ω). The data in (b) and (c) are presented as mean values ± s.d. (n = 3). In situ ATR-SEIRAS and the corresponding contour maps of (d) Sn₁/NCB and (e) Sn₂/NCB during NO₃RR. f The charge density difference plots of NO₃⁻ on Sn₂/NCB and Sn₁/NCB. g The adsorption energies of NO₃⁻ on CB, NCB, Sn₁/NCB, and Sn₂/NCB. h Gibbs free energy curves of NO₃⁻ reduction on Sn₂/NCB. The inset molecular structures represent the most thermodynamically favorable N₂ generation path on Sn₂/NCB. Transition state energy diagrams of (i) *H and (j) *N spillover on Sn₂/NCB and Sn₁/NCB. Red, blue, white, and grey atoms represent O, N, H, and C elements respectively. Source data are provided as a Source Data file.