Tobacco stem-derived nitrogen-containing porous carbon with highly dispersed Ni–N sites as an efficient electrocatalyst for CO2 reduction to CO

Abstract

Electrochemical CO₂ reduction is considered as a promising strategy for CO₂ conversion and utilization. However, developing efficient and low-cost electrocatalysts still remains a great challenge. Herein, Ni–N@NPC was prepared using tobacco stem derived nitrogen-containing porous carbon (NPC) as a support and 1,10 phenanthroline as a chelating agent, as well as nickel(II) acetate tetrahydrate as a Ni source. The prepared Ni–N@NPC has highly dispersed Ni–N sites and good CO₂ adsorption capacity. Ni–N@NPC exhibits excellent electrochemical CO₂ reduction property, including high faradaic efficiency for CO (about 98.44%) at a medium overpotential of 670 mV and high activity (current density approximately 30.96 mA cm⁻²), as well as durable stability over 30 hours. In addition, the Ni–N@NPC still maintains a Faraday efficiency over 90.5% at wide potentials (from −0.57 V to −0.87 V). DFT calculation reveals that Ni–N sites decrease the kinetic energy barriers for *CO₂ transition to *COOH, indicating that the high electrochemical CO₂ reduction activity is attributed to the Ni–N sites in electrocatalysts. This work provides a new way to develop biomass carbon materials and promote their application in energy conversion.