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. 2023 Jun 13;28(12):4738.
doi: 10.3390/molecules28124738.

CNTs/Fe-BTC Composite Materials for the CO2-Photocatalytic Reduction to Clean Fuels: Batch and Continuous System

Elizabeth Rojas García  1   2 , Gloria Pérez-Soreque  3 , Ricardo López Medina  4 , Fernando Rubio-Marcos  5   6 , Ana M Maubert-Franco  3
Affiliations

CNTs/Fe-BTC Composite Materials for the CO2-Photocatalytic Reduction to Clean Fuels: Batch and Continuous System

Elizabeth Rojas García et al. Molecules. .

Abstract

CNTs/Fe-BTC composite materials were synthesized with the one-step solvothermal method. MWCNTs and SWCNTs were incorporated in situ during synthesis. The composite materials were characterized by different analytical techniques and used in the CO2-photocatalytic reduction to value-added products and clean fuels. In the incorporation of CNTs into Fe-BTC, better physical-chemical and optical properties were observed compared to Fe-BTC pristine. SEM images showed that CNTs were incorporated into the porous structure of Fe-BTC, indicating the synergy between them. Fe-BTC pristine showed to be selective to ethanol and methanol; although, it was more selective to ethanol. However, the incorporation of small amounts of CNTs into Fe-BTC not only showed higher production rates but changes in the selectivity compared with the Fe-BTC pristine were also observed. It is important to mention that the incorporation of CNTs into MOF Fe-BTC allowed for increasing the mobility of electrons, decreasing the recombination of charge carriers (electron/hole), and increasing the photocatalytic activity. In both reaction systems (batch and continuous), composite materials showed to be selective towards methanol and ethanol; however, in the continuous system, lower production rates were observed due to the decrease in the residence time compared to the batch system. Therefore, these composite materials are very promising systems to convert CO2 to clean fuels that could replace fossil fuels soon.

Keywords: CNTs/Fe-BTC; CO2; CO2-photocatalytic reduction; Fe-BTC; MWCNTs; SWCNTs; clean fuels.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
(A) XRD patterns of the MOF Fe-BTC and of the composite materials with different percentages of MWCNT, and (B) Spectra Raman of MWCNT, MOF Fe-BTC, and composite materials.
Figure 2
Figure 2
Raman spectra of all the materials, (A) MWCNTs’ series, and (B) SWCNTs’ series.
Figure 3
Figure 3
FTIR spectra of the materials, (A) MWCNTs’ series, and (B) SWCNTs’ series.
Figure 4
Figure 4
Identification of the morphology of the CNT/Fe-BTC composite materials. Morphology of (A,B) 1.5% MWCNT/Fe-BTC and (C–E) 1.5% SWCNT/Fe-BTC composite materials.
Figure 5
Figure 5
UV-Vis absorption spectra of (A) MWCNT series and (B) SWCNT series.
Figure 6
Figure 6
CO2 adsorption isotherm at 298 K and low pressure for Fe-BTC pristine and composite materials, (A) MWCNT series, and (B) SWCNT series.
Figure 7
Figure 7
Possible reaction mechanism for the photocatalytic reduction reaction of CO2 using the composite materials.
Figure 8
Figure 8
Reaction system for the photocatalytic reduction of CO2, (A) batch system, and (B) continuous system.
See this image and copyright information in PMC

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