N/S Dually Doped Nanoporous Carbon for CO2 Adsorption

In this study, we prepared N/S-codoped porous carbon materials via a one-step doping method using lignin as the carbon source, thiourea as the N and S source, and KOH as the activator. The synthesized material exhibited a rich N content and a certain S content. The important reason the CO2 adsorption characteristic of the carbon materials were investigated by modulating the thiourea proportion and doping temperature. Results indicate that at a thiourea ratio of 1:4 and a doping temperature of 700 °C, the material exhibited an outstanding CO2 adsorption capacity of 3.49 mmol/g. Various characterizations revealed that such a high adsorption capacity is attributed to the combination of a microporous structure and excellent surface chemical properties. The doping of S atoms resulted in the formation of effective active sites, increased the defect density of the material, and promoted the generation of N functional groups, thereby enhancing the efficiency of CO2 adsorption. In addition, the material exhibits high CO2/N2 selectivity and cycling stability. The overall results indicate that lignin-derived N/S-codoped porous carbon can serve as a potential adsorbent for CO2 capture.