Tuning the Properties of N-Doped Biochar for Selective CO₂ Electroreduction to CO

Nitrogen-doped (N-doped)carbon catalysts have been widely studiedfor electrochemical CO2 reduction to CO. However, the correlationbetween the physicochemical properties of N-doped carbon catalystsand their electrocatalytic performance for the CO2RR isstill unclear. Herein, a series of N-doped biochar catalysts withdifferent physicochemical properties were synthesized by tuning thecarbonization temperature and N-doping level and used for the CO2RR to analyze the structure-performance relationship.The prepared catalysts exhibited massive differences in maximum faradaicefficiency to CO from 26.8 to 94.9% at around -0.8 to -0.9V vs RHE. In addition, we find that simply increasing the specificsurface area and N-doping level of the catalysts does not effectivelyimprove the catalytic performance for the CO2RR. A multivariatecorrelation analysis reveals a negative correlation between the N-dopingcontent and the electrochemical performance. The porous structuralproperties exhibit a positive correlation to the FECO butalmost no correlation to j (CO). Interestingly,improving the degree of graphitization, surface hydrophobicity, theabundance of defects, and optimizing the porosity of the N-doped biocharcatalyst can efficiently enhance the catalytic performance for theCO(2)RR. We conclude that comprehensively analyzing the synergisticeffect of various properties of N-doped biochar is critical to revealstructure-activity relationships.