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

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 (NiNxCNT), 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 NiNxCNT 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–Nx 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.