Fig. 2: Electrocatalytic NO₃RR performance of Co₆Ni₄.

a LSV curves (without iR compensation) of Co₆Ni₄, Co, and Ni catalysts for NO₃RR and HER. b FE, c Yield rate, and d Energy efficiency of NH₃ for Co₆Ni₄, Co, and Ni catalysts (potentials are not iR-corrected). The chronoamperometry tests were performed in various applied potentials for 1 h to evaluate the NO₃RR performance of prepared catalysts. e Stability test of Co₆Ni₄ catalyst for 120 h continuous NO₃RR at − 0.476 V (vs. RHE) (without iR compensation), during which the electrolyte was sampled for FE and yield calculation every 3 h, and then the cell chambers were filled with fresh electrolyte. The electrolyte for NO₃RR and HER is 1 M KOH solution with and without 0.3 M KNO₃. f ¹H NMR spectra of the electrolytes after NO₃RR using 0.1 M K¹⁴NO₃ and K¹⁵NO₃ as the nitrogen sources or without nitrate. g Comparison of FE and yield rate of NH₃ produced by Co₆Ni₄ catalyst measured by UV-vis spectrophotometer and NMR. h Comparisons of NO₃RR performances between Co₆Ni₄ and recent reported catalysts. The overpotential corresponding to the 1 A cm⁻² is inversely proportional to the color intensity. The error bar represents the standard deviation of the data from three independent experiments. The source data for the above figures are provided as a Source Data file.