Novel folic acid complex derived nitrogen and nickel co-doped carbon nanotubes with embedded Ni nanoparticles as efficient electrocatalysts for CO2 reduction

Abstract

Electrochemical reduction of CO₂ to value-added products with high selectivity has attracted significant research interest. The development of earth-abundant and low-cost electrocatalysts is the key in this process. Herein, an efficient CO₂ reduction electrocatalyst, comprising Ni and N in situ co-doped into porous and Ni nanoparticle-embedded carbon nanotubes (NiN_xCNT), is developed from a sustainable and representative bioligand – folic acid. The synthesis process is straightforward, with the crucial step being the chelation of folic acid and Ni ions into uniform tubular metal–organic complex precursor. The resulted NiN_xCNT catalyst exhibits a CO partial current density of 9.0 mA cm⁻² at −0.676 V versus RHE and a high selectivity towards CO (>98%) in a wide potential range of −0.676 to −0.976 V versus RHE. Furthermore, the electrode shows little current decay over a period of total 44 h continuous operation at different potentials. The notable performance here is attributed to the synergistic effect of rich Ni–N_x sites and hierarchically porous nanotube structure. The findings of this study will open new avenues for developing inexpensive and high-performance CNT-based electrocatalysts for CO₂ utilization.