1D/2D nitrogen-doped carbon nanorod arrays/ultrathin carbon nanosheets: outstanding catalysts for the highly efficient electroreduction of CO2 to CO

Abstract

The electroreduction of carbon dioxide (CO₂) to value-added chemicals is a promising strategy for alleviating both the greenhouse effect and the energy crisis. However, conventional electrocatalysts generally suffer from low energy efficiency and poor product selectivity and durability. Herein, one/two-dimensional nitrogen-doped carbon nanorod arrays/ultrathin carbon nanosheet catalysts (1D/2D NR/CS-X) with high specific surface area and N doping were designed and prepared by in situ polymerization of aniline in the presence of ultrathin carbon nanosheets originating from the thermal expansion of calcium gluconate and acid treatment, followed by pyrolysis. 1D/2D NR/CS-900 was capable of converting CO₂ to CO with the Faraday efficiency of up to 94.2% at −0.45 V vs. RHE, retaining its activity for at least 30 h, and exhibited an onset overpotential as low as 97 mV, which surpassed all the reported doped carbon materials and was comparable to single-atom metal catalysts. The Tafel slope of 1D/2D NR/CS-900 was only 65 mV dec⁻¹, which indicated a rapid pre-equilibrating one-electron transfer followed by a rate-determining reaction step. DFT calculations revealed that the pyridinic N and unique 1D/2D structure of NR/CS-X could significantly lower the free energy barriers of *COOH and *CO intermediate formation and boost CO desorption; this led to the highly efficient electroreduction of CO₂ to CO.