Decoding the N-doping mechanism for enhanced CO2 adsorption on biochar

• A new type of biochar was prepared using various organic amine reagents as nitrogen sources. • The 1.2N/BC attains a CO₂ uptake of 4.99 mmol g -1 at 25 °C and 1.6 MPa, attributable to enhanced N-doping. • Computational modeling of the enhancement mechanism for CO₂ adsorption on nitrogen-doped biochar. • The use of biochar adsorbents to capture carbon dioxide in the industrial field is a promising method. The growing demand for efficient carbon capture technologies has led to the exploration of biochar as a promising material for CO 2 adsorption, particularly through modifications such as nitrogen doping to enhance its performance. In this study, a series of biochars were prepared using different types of amine reagents and varying amounts of nitrogen doping. The highest adsorption capacity, 4.99 mmol g -1 , was achieved at 25 °C and 1.6 MPa when ethylenediamine was employed as the nitrogen source, with a mass ratio of the amine reagent to biochar of 1.2. Correlation analysis indicated that both physical and chemical adsorption significantly influenced CO 2 adsorption capacity. Additionally, by constructing biochar models with varying nitrogen contents and different nitrogen doping forms, theoretical calculations revealed that nitrogen doping could enhance the adsorption energy between CO 2 and biochar. This improvement in adsorption performance was more pronounced with higher nitrogen content. In this work, not only N-doped biochar with excellent CO 2 adsorption performance was prepared from waste biomass, but also the promotion mechanism of N-doped was revealed in detail by combining theoretical calculations and experiments.