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Probing the role of O-containing groups in CO2 adsorption of N-doped porous activated carbon

Abstract

Porous activated carbons (PAC) are promising candidates to capture CO2 through physical adsorption because of their chemical stability, easy-synthesis, cost-effectiveness and good recyclability. However, low CO2 adsorption capacity, especially low CO2/N2 selectivity, limits their practical applications. In this work, an optimized PAC with large specific surface area, small micropore size, and large micropore volume has been synthesized by one-step carbonization/activation of casein using K2CO3 as a mild activation agent. And it showed a remarkably enhanced CO2 adsorption capacity as high as 5.78 mmol g-1 and excellent CO2/N2 selectivity of 144 (25 oC, 1 bar). Based on DFT calculation and experimental results, the coexistence of adjacent pyridinic N and -OH/-NH2 species was proposed for the first time to make an important contribution to the ultra-high CO2 adsorption performance, especially CO2/N2 selectivity. This work provides an effective guidance to design PAC adsorbents with high CO2 adsorption performance. The content of pyridine N combined with -OH/-NH2 was further elevated by additional nitrogen introduction, resulting further enhanced CO2 adsorption capacity up to 5.96 mmol g-1 (25 oC, 1 bar). All these results suggest that, in addition to the well-defined pore structure, pyridinic N with neighboring OH or NH2 species played an important role in enhancing the CO2 adsorption performance of PAC, thus providing an effective guidance for the rational design of CO2 adsorbents.

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Publication details

The article was received on 12 Aug 2017, accepted on 11 Oct 2017 and first published on 11 Oct 2017


Article type: Paper
DOI: 10.1039/C7NR05977A
Citation: Nanoscale, 2017, Accepted Manuscript
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    Probing the role of O-containing groups in CO2 adsorption of N-doped porous activated carbon

    M. Wang, X. Fan, L. Zhang, J. Liu, B. Wang , R. Cheng, M. Li, J. Tian and J. Shi, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR05977A

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