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

Abstract

Nitrogen-doped (N-doped) carbon catalysts have been widely studied for electrochemical CO 2 reduction to CO. However, the correlation between the physicochemical properties of N-doped carbon catalysts and their electrocatalytic performance for the CO 2 RR is still unclear. Herein, a series of Ndoped biochar catalysts with different physicochemical properties were synthesized by tuning the carbonization temperature and N-doping level and used for the CO 2 RR to analyze the structure−performance relationship. The prepared catalysts exhibited massive differences in maximum faradaic efficiency to CO from 26.8 to 94.9% at around −0.8 to −0.9 V vs RHE. In addition, we find that simply increasing the specific surface area and N-doping level of the catalysts does not effectively improve the catalytic performance for the CO 2 RR. A multivariate correlation analysis reveals a negative correlation between the Ndoping content and the electrochemical performance. The porous structural properties exhibit a positive correlation to the FE CO but almost no correlation to j CO . Interestingly, improving the degree of graphitization, surface hydrophobicity, the abundance of defects, and optimizing the porosity of the N-doped biochar catalyst can efficiently enhance the catalytic performance for the CO 2 RR. We conclude that comprehensively analyzing the synergistic effect of various properties of N-doped biochar is critical to reveal structure−activity relationships.

One-pot synthesis of biomass-derived porous carbons for multipurpose energy applications

“…, N) doping on the biochar matrix. 233–235 Recently, Fu et al 236,237 prepared N-doped carbons from biomass for the CO 2 RR. The correlation between activators, properties, and electrocatalytic performance was investigated.…”

“…236 Improving the graphitization degree, surface hydrophobicity, abundance of defects, and porosity of the N-doped biochar catalyst can efficiently enhance its CO 2 RR performance. 237 Therefore, metal-free carbon materials with oxygen, nitrogen, boron, sulfur or phosphorus functionalities have emerged as sustainable and cost-efficient heterogeneous catalysts. The detailed information regarding the design of metal-free carbon materials from biomass and the relationship between their structure and activity in electro-, photo-, and thermo-catalysis can be found in the recent review paper.…”

From Waste to Resource: Valorization of Lignocellulosic Agri-Food Residues through Engineered Hydrochar and Biochar for Environmental and Clean Energy Applications—A Comprehensive Review

“…This superiority was evident through the increased selectivity for CO and the heightened current density achieved at the ZnO/Chitosan electrode (75.6 mA/cm 2 at −1.3 V vs. RHE). Fu et al [160] prepared a series of N-doped biochars derived from sugarcane bagasse for evaluation as CO 2 -RR catalysts. The prepared catalyst showcased substantial disparities in their maximum faradaic efficiency concerning CO, ranging from 26.8% to an impressive 94.9% within the voltage range of approximately −0.8 to −0.9 V vs. RHE.…”

Benefits of Using Rapid Microwave Heating in the Synthesis of Metal-Free Carbon Electrocatalysts

“…However, traditional methods of heating, which rely on bulk heating, have limitations when it comes to tuning the desired properties of carbon materials. For example, recent studies on electrochemical reduction of O 2 or CO 2 indicate the general significance of high electron conductivity and pore hydrophobicity for carbon-based electrocatalysts. , One way to achieve this goal involves subjecting the carbon material to heat treatment above 1100 °C. , However, this process unavoidably eliminates the necessary nitrogen dopants and carbon defects as well . An alternative is to heat the carbon material in the presence of NH 3 .…”