Structural optimization of ZIF-8-derived porous N-doped carbon materials for effective CO2 capture

Abstract

In this research, ZIF-8-derived porous nitrogen-doped carbon materials (ZNCs) with adjustable pore width structures and N/O functional groups are prepared via low temperature carbonization with the help of different additives. By introducing different compounds (C₉H₆O₆, C₃H₂N₂, C₁₆H₃₂O₂, C₁₂H₂₂O₁₁, C₂H₄N₄, C₃H₆N₆, Na₃PO₄, Na₂SO₄, CH₃COONa, KOH, Na₂CO₃, and KHCO₃) during the pyrolysis process, it is feasible to modulate the BET specific surface area, pore structure, and content of different N/O species of ZNCs. The influence of pore size ranges and contents of different N/O species on the CO₂ capture efficiency of ZNCs is investigated. A multiple linear regression equation is constructed with V_0–10 Å, V_7–9 Å, pyrrole-N content, COOH content, and O–H content as the independent variables, and CO₂ capture performance of ZNCs as the dependent variable. The results show that V_0–10 Å serves as a critical determinant of CO₂ capture performance under standard conditions (25 °C, 1 bar), with pyrrole-N content and O–H content playing a secondary role. Among all the samples, 2ZNC–KHCO₃-600 has the most excellent CO₂ capture efficiency, demonstrating adsorption capacities of 4.60 mmol g⁻¹ at 25 °C and 6.55 mmol g⁻¹ at 0 °C under 1 bar pressure. In addition, 2ZNC–KHCO₃-600 exhibits remarkable CO₂/N₂ selectivity (38.2) and cycling stability. This study provides valuable insights into the development of nitrogen-doped porous carbon materials with excellent CO₂ capture capacity, as well as new insights into the understanding of the determining factors influencing the CO₂ capture ability of nitrogen-doped porous carbon.