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Conductive Graphitic Carbon Nitride as an Ideal Material for Electrocatalytically Switchable CO2 Capture.

Tan X, Kou L, Tahini HA, Smith SC - Sci Rep (2015)

Bottom Line: At saturation CO2 capture coverage, the negatively charged g-C4N3 nanosheets achieve CO2 capture capacities up to 73.9 × 10(13) cm(-2) or 42.3 wt%.In addition, these negatively charged g-C4N3 nanosheets are highly selective for separating CO2 from mixtures with CH4, H2 and/or N2.These predictions may prove to be instrumental in searching for a new class of experimentally feasible high-capacity CO2 capture materials with ideal thermodynamics and reversibility.

View Article: PubMed Central - PubMed

Affiliation: Integrated Materials Design Centre (IMDC), School of Chemical Engineering, UNSW Australia, Sydney, NSW 2052, Australia.

ABSTRACT
Good electrical conductivity and high electron mobility of the sorbent materials are prerequisite for electrocatalytically switchable CO2 capture. However, no conductive and easily synthetic sorbent materials are available until now. Here, we examined the possibility of conductive graphitic carbon nitride (g-C4N3) nanosheets as sorbent materials for electrocatalytically switchable CO2 capture. Using first-principle calculations, we found that the adsorption energy of CO2 molecules on g-C4N3 nanosheets can be dramatically enhanced by injecting extra electrons into the adsorbent. At saturation CO2 capture coverage, the negatively charged g-C4N3 nanosheets achieve CO2 capture capacities up to 73.9 × 10(13) cm(-2) or 42.3 wt%. In contrast to other CO2 capture approaches, the process of CO2 capture/release occurs spontaneously without any energy barriers once extra electrons are introduced or removed, and these processes can be simply controlled and reversed by switching on/off the charging voltage. In addition, these negatively charged g-C4N3 nanosheets are highly selective for separating CO2 from mixtures with CH4, H2 and/or N2. These predictions may prove to be instrumental in searching for a new class of experimentally feasible high-capacity CO2 capture materials with ideal thermodynamics and reversibility.

No MeSH data available.


The adsorption energies of CO2, CH4, H2, N2 and H2O on neutral, 1 e– and 2 e– negatively charged g-C4N3.
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f7: The adsorption energies of CO2, CH4, H2, N2 and H2O on neutral, 1 e– and 2 e– negatively charged g-C4N3.

Mentions: CH4, H2, N2 are three types of gas mixtures that are currently most interesting for CO2 capture technologies, namely, postcombustion (predominantly CO2/N2 separation), natural gas sweetening (CO2/CH4), and precombustion (CO2/H2) capture37. In order to demonstrate the high selectivity of negatively charged g-C4N3 nanosheets for CO2 capture, we calculated the adsorption energies of CH4, H2 and N2 on neutral and negatively charged g-C4N3 and compared with those of CO2. In Fig. 7 we list the comparative adsorption energies of CO2, CH4, H2, and N2 on neutral, 1 e− and 2 e− negatively charged g-C4N3 (corresponding lowest-energy configurations are shown in Figure S2 of the Supporting Information). Clearly, the adsorptions of CH4, H2 and N2 on neutral, 1 e− and 2 e− g-C4N3 are all physical rather than chemical. The distance between the carbon atom of CH4 (the hydrogen atom of H2, the nitrogen atom of N2) and g-C4N3 is 3.157–3.159 (2.111–2.539, 2.865–3.236) Å, respectively. The adsorption energies of CH4, H2 and N2 on neutral, 1 e− and 2 e− g-C4N3 range from 0.06 to 0.39 eV. In contrast, although CO2 is physically adsorbed at neutral and 1 e− g-C4N3 with small adsorption energy in the range from 0.24 to 0.32 eV, CO2 is tightly chemisorbed on 2 e− g-C4N3 with large adsorption energy of 1.20 eV. The above comparisons demonstrate that negatively charged g-C4N3 has very high selectivity for capturing CO2 from CH4, H2 and/or N2 mixtures.


Conductive Graphitic Carbon Nitride as an Ideal Material for Electrocatalytically Switchable CO2 Capture.

Tan X, Kou L, Tahini HA, Smith SC - Sci Rep (2015)

The adsorption energies of CO2, CH4, H2, N2 and H2O on neutral, 1 e– and 2 e– negatively charged g-C4N3.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4664948&req=5

f7: The adsorption energies of CO2, CH4, H2, N2 and H2O on neutral, 1 e– and 2 e– negatively charged g-C4N3.
Mentions: CH4, H2, N2 are three types of gas mixtures that are currently most interesting for CO2 capture technologies, namely, postcombustion (predominantly CO2/N2 separation), natural gas sweetening (CO2/CH4), and precombustion (CO2/H2) capture37. In order to demonstrate the high selectivity of negatively charged g-C4N3 nanosheets for CO2 capture, we calculated the adsorption energies of CH4, H2 and N2 on neutral and negatively charged g-C4N3 and compared with those of CO2. In Fig. 7 we list the comparative adsorption energies of CO2, CH4, H2, and N2 on neutral, 1 e− and 2 e− negatively charged g-C4N3 (corresponding lowest-energy configurations are shown in Figure S2 of the Supporting Information). Clearly, the adsorptions of CH4, H2 and N2 on neutral, 1 e− and 2 e− g-C4N3 are all physical rather than chemical. The distance between the carbon atom of CH4 (the hydrogen atom of H2, the nitrogen atom of N2) and g-C4N3 is 3.157–3.159 (2.111–2.539, 2.865–3.236) Å, respectively. The adsorption energies of CH4, H2 and N2 on neutral, 1 e− and 2 e− g-C4N3 range from 0.06 to 0.39 eV. In contrast, although CO2 is physically adsorbed at neutral and 1 e− g-C4N3 with small adsorption energy in the range from 0.24 to 0.32 eV, CO2 is tightly chemisorbed on 2 e− g-C4N3 with large adsorption energy of 1.20 eV. The above comparisons demonstrate that negatively charged g-C4N3 has very high selectivity for capturing CO2 from CH4, H2 and/or N2 mixtures.

Bottom Line: At saturation CO2 capture coverage, the negatively charged g-C4N3 nanosheets achieve CO2 capture capacities up to 73.9 × 10(13) cm(-2) or 42.3 wt%.In addition, these negatively charged g-C4N3 nanosheets are highly selective for separating CO2 from mixtures with CH4, H2 and/or N2.These predictions may prove to be instrumental in searching for a new class of experimentally feasible high-capacity CO2 capture materials with ideal thermodynamics and reversibility.

View Article: PubMed Central - PubMed

Affiliation: Integrated Materials Design Centre (IMDC), School of Chemical Engineering, UNSW Australia, Sydney, NSW 2052, Australia.

ABSTRACT
Good electrical conductivity and high electron mobility of the sorbent materials are prerequisite for electrocatalytically switchable CO2 capture. However, no conductive and easily synthetic sorbent materials are available until now. Here, we examined the possibility of conductive graphitic carbon nitride (g-C4N3) nanosheets as sorbent materials for electrocatalytically switchable CO2 capture. Using first-principle calculations, we found that the adsorption energy of CO2 molecules on g-C4N3 nanosheets can be dramatically enhanced by injecting extra electrons into the adsorbent. At saturation CO2 capture coverage, the negatively charged g-C4N3 nanosheets achieve CO2 capture capacities up to 73.9 × 10(13) cm(-2) or 42.3 wt%. In contrast to other CO2 capture approaches, the process of CO2 capture/release occurs spontaneously without any energy barriers once extra electrons are introduced or removed, and these processes can be simply controlled and reversed by switching on/off the charging voltage. In addition, these negatively charged g-C4N3 nanosheets are highly selective for separating CO2 from mixtures with CH4, H2 and/or N2. These predictions may prove to be instrumental in searching for a new class of experimentally feasible high-capacity CO2 capture materials with ideal thermodynamics and reversibility.

No MeSH data available.