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

The growing demand for efficient carbon capture technologies has led to the exploration of biochar as a promising material for CO2 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 CO2 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 CO2 and biochar. This improvement in adsorption performance was more pronounced with higher nitrogen content. In this work, not only N-doped biochar with excellent CO2 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.