Ultra-microporous cotton fiber-derived activated carbon by a facile one-step chemical activation strategy for efficient CO2 adsorption

The CO2 capture by absorbent shows a great promise to remit the pressure of CO2 discharge. The functionalization of N surfaces and the development of the surface area in activation modification have received a great deal of attention as important factors influencing CO2 adsorption performance. However, the role of ultra-micropores in the capture by size matching of CO2 by adjusting the CO2 size and the absorbent pore structure has been less studied to some extent. The study provides a simple one-step chemical activation method, in which cotton fibers were utilized as biomass sources to construct ultra-microporous carbon absorbent with a simple and effective tunable pore structure by changing the alkali-carbon ratio and activation temperature. The series of samples both showed high CO2 adsorption at normal pressure, in particular, the optimal sample CC2-800 affords 4.43 mmol g-1 CO2 uptake at 298 K and 6.58 mmol g-1 CO2 uptake at 273 K. Impressively, the optimal adsorbent was endowed with extremely low adsorption heat, thereby showing good reversibility and reusability during multiple-cycle tests at room temperature. By a comprehensive study of the structural characteristics of the adsorbent, this research further validates the significant role of ultra-micropores in CO2 adsorption. Additionally, the simple one-step preparation process shows crucial significance for sustainable development and environmental friendliness, which provides some interesting insights for the design and development of ultramicroporous activated carbon.