Synthesis and CO2 capture properties of mesoporous carbon nitride materials

► Mesoporous carbon nitrides and carbon nitride–carbon composites were synthesized for CO2 capture. ► High CO2 adsorption capacity with good reusability and CO2/N2 selectivity is obtained. ► The introduction of carbon coating layer improved the microporosity, favoring the CO2 capture. ► Both the high surface area and the presence of N contributed to the high CO2 capture capacity. Mesoporous carbon nitride (MCN) and carbon nitride–carbon (MCN/C) composites with a partly graphitized structure are synthesized by using mesoporous silica SBA-15 as a hard template and ethylenediamine and carbon tetrachloride as precursors, possessing uniform mesopore size of 6.3nm, high surface area of 278–338m2/g, and high nitrogen content of 20.5–24.9% with abundant basic sites. The synthesized MCN and MCN/C composites are used as adsorbents for CO2 capture, showing high adsorption capacity and good reusability. The presence of carbon coating layer in MCN/C composites introduced more micropores, which favored the capture of CO2, exhibiting high CO2 capture capacity of 3.05mmol/g at 0°C and 2.35mmol/g at 25°C and 760mmHg, with good CO2/N2 selectivity and excellent regeneration stability.