In-situ pyrolysis of Taihu blue algae biomass as appealing porous carbon adsorbent for CO2 capture: Role of the intrinsic N

An environment-friendly, cost-effective, and facile N self-doping porous carbon (NC) were prepared through in-situ pyrolysis of nitrogen abundant Taihu blue algae biomass for CO2 uptake. It was found that the CO2 sorption capacity of porous carbon prepared through carbonization at 800 °C with KOH activation (N-C-800) exhibit higher CO2 uptake capacity of 4.88 (1 bar and 0 °C) and 2.76 mmol/g (1 bar and 25 °C) respectively, with the CO2/N2 selectivity of N-C-800 attaining 39.3. Besides, the adsorption capacity of N-C-800 remained stable even after 7 repeated cycles, with a slight loss of nearly 6%. Moreover, total graphitic N (Ntg) sources from the intrinsic N in N-C-800 is not only higher than other agro-sourced porous carbon materials, but the graphitic N performed a sound correlation with the CO2 uptake capacity. Combining experiments with Density Functional Theory (DFT) calculations, higher adsorption energy of N-C-800 (−13.6 kJ/mol, comparing with −6.9 kJ/mol of N-free carbon framework) would render the efficient adsorption of CO2 molecular onto the graphitic N site. The current study not only provides a new option for the reclamation of Taihu blue algae biomass as N self-doping material, but a proof-of-concept investigation employing NC materials as an appealing candidate for CO2 capture.