Ultramicroporous silicon nitride ceramics for CO2 capture

Carbon dioxide (CO2) capture is regarded as one of the biggest challenges of the 21st century; therefore, intense research effort has been dedicated in the area of developing new materials for efficient CO2 capture. Here, we report high CO2 capture capacity in the low region of applied CO2 pressures observed with ultramicroporous silicon nitride-based material. The latter is synthesized by a facile one-step NH3-assisted thermolysis of a polysilazane. Our newly developed material for CO2 capture has the following outstanding properties: (i) one of the highest CO2 capture capacities per surface area of micropores, with a CO2 uptake of 2.35 mmol g−1 at 273 K and 1 bar (ii) a low isosteric heat of adsorption (27.6 kJ mol−1), which is independent from the fractional surface coverage of CO2. Furthermore, we demonstrate that the pore size plays a crucial role in elevating the CO2 adsorption capacity, surpassing the effect of Brunauer–Emmett–Teller specific surface area.