Modulated synthesis of N-doped porous carbons via rational design of the poly(ionic liquid) precursors towards efficient CO2 separation

A ternary copolymerized poly(ionic liquid) of bis-imidazolium-based ionic liquid and crosslinking agents (divinylbenzene (DVB), N, N′-methylene bisacrylamide (MBA)) was rationally designed as versatile precursor to synthesize nitrogen-doped porous carbons by self-templating method for efficient CO 2 separation. The ionic liquid monomer and MBA could serve as nitrogen sources to enhance the surface polarity through in-situ doping, while the self-decomposed functional groups (especially -CONH-) along with halogen anions could promote the formation of pores during carbonization . By adjusting the molar ratio of ionic liquid to DVB and MBA, carbonization temperature and activator dosage (KOH), the obtained CVDM 0.5 -700 (0.5:1:1, 700 °C, 2 mol/L) owned a considerable specific surface area (1835 m 2 /g), plentiful (ultra)micropores and moderate nitrogen content (3.05 wt%). The strong van der Waals force arising from ultra-micropores (d<0.7 nm) within a narrow distribution improved the ability to capture CO 2 and the abundant CO 2 -philic N species further strengthened the binding interactions. Consequently, CVDM 0.5 -700 was endowed with satisfactory CO 2 uptake capacity (4.11 mmol/g), desirable CO 2 /N 2 (15%/85%) adsorption selectivity (23.6) and excellent cyclic stability at 25 °C and normal pressure. This work provided a new pathway for the modulated fabrication of heteroatoms-doped porous carbon materials by precise design of poly(ionic liquid)-based precursors for appealing applications.