Fig. 2

N₂ reduction reaction performance of the electrocatalysts. a The linear sweep voltammogram (LSV) curves of Cu/PI-300 (catalyst loading: 5 mg cm⁻²) measured at a scan rate of 10 mV s⁻¹ under the Ar and N₂ atmosphere. b The Faradaic efficiencies of bare PI-300, Cu/PI-300, and Cu/C for NH₃ generation at −0.3 V vs. RHE within 6 h. The Faradaic efficiencies (spheres) and NH₃ yield rates (bars) of Cu/PI-300 with varied catalyst loadings at −0.3 V vs. RHE c or with a fixed catalyst loading (5 mg cm⁻²) at different work potentials d within 6 h. Insets: a ¹H NMR spectra of both ¹⁴NH₄⁺ and ¹⁵NH₄⁺ produced from the NRR reaction using ¹⁴N₂ and ¹⁵N₂ gas respectively