Ni-Cu bimetallic alloy anchored on nitrogen-doped carbon nanotubes for CO₂-to-CH₄ electrochemical conversion

Electrocatalytic CO₂ reduction to CH₄ remains challenging due to multi-electron transfer and intermediates adsorption. Herein, we synthesized electrocatalysts by growing Ni-Cu alloy structure on nitrogen-doped carbon nanotubes (Ni_xCu_y-NCNT) for electrocatalytic CO₂ reduction reaction (CO₂RR) via hydrothermal method followed by pyrolysis. The optimized Ni₁Cu₁-NCNT demonstrated a superior CO₂RR performance, achieving 99.7% \(\text{FE}_{\text{CH}_{4}}\) $${\text{FE}}_{{\text{CH}}_4}$$ (FE = Faradaic efficiency) and 11.54 mA • cm⁻² current density at −1.2 V vs. reversible hydrogen electrode (RHE), which outperformed single metal counterparts. Its outstanding performance was due to the electrons transferred from Cu to Ni and Ni-Cu alloy shifted the d-band center toward the Fermi level, which was more conducive to the intermediate formation. In situ electrochemical attenuated total reflection (EC-ATR) and density functional theory (DFT) calculations revealed the appearance of *CHO intermediate and the pathway during the CO₂RR process. The design of the bimetallic electrocatalyst in this study provides a new perspective for the highly selective reduction of CO₂.