Selenium‐Doped Hierarchically Porous Carbon Nanosheets as an Efficient Metal‐Free Electrocatalyst for CO2 Reduction

Abstract Electrochemical carbon dioxide reduction reaction (CO 2 RR) provides a promising pathway for both decreasing atmospheric CO 2 concentration and producing valuable carbon‐based fuels. To explore efficient and cost‐effective catalysts for electrochemical CO 2 RR is of great importance, but remains challenging. Se‐doped carbon nanosheets (Se‐CNs) with a micro‐, meso‐, and macroporous structure are proposed for electrochemical CO 2 RR. Such an electrocatalyst combines the advantages of Se optimized active sites, hierarchical pores for facilitating reactant or ion penetration, transport and reaction, and large surface area for more accessible active sites. This Se‐CNs electrocatalyst exhibits over 11‐times enhanced partial current density of CO than the CNs without Se doping and high selectivity (90%) for CO 2 electroreduction to CO at a low potential of −0.6 V versus the reversible hydrogen electrode (vs RHE). Density function theoretical calculations reveal that the Se introduction in CNs lowers the free energy barrier of CO 2 RR and inhibits hydrogen evolution reaction effectively, thus improving the selectivity for CO 2 reduction to CO. This work presents a new member of the metal‐free electrocatalyst family, which is easily prepared, low cost, adjustable, and highly efficient for CO 2 RR.