Fig. 4. Electrochemical CO₂RR performances.

a LSV curves at scan rate of 10 mV/s in H-cell with pure CO₂ saturated 0.5 M KHCO₃ solution. b FE_CO at different potentials in H-cell under pure CO₂. c FE_CO and J_CO of Ni@C₃N₄-CN at different potentials under 30% CO₂ concentration. d In situ XANES spectra of Ni@C₃N₄-CN measured at different potentials. e In situ k³ weighted Fourier transform EXAFS spectra of Ni@C₃N₄-CN. f The potentials and FE_CO at different current densities of Ni@C₃N₄-CN in flow cell under pure CO₂. g Stability of Ni@C₃N₄-CN at a current density of −100 mA/cm² in flow cell under pure CO₂. h CO₂ TPD curves of Ni@C₃N₄-CN, Ni@C₃N₄, C₃N₄-CN catalyst. i In situ ATR-IR spectra of Ni@C₃N₄-CN. The error bars correspond to the standard deviations of measurements over three separately prepared samples under the same testing conditions.