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

Abstract

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.