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. 2022 Jan 27;14(3):523.
doi: 10.3390/polym14030523.

Methylene Blue Dye as Photosensitizer for Scavenger-Less Water Photo Splitting: New Insight in Green Hydrogen Technology

Nasser A M Barakat  1 , Gehan M K Tolba  1 , Khalil Abdelrazek Khalil  2
Affiliations

Methylene Blue Dye as Photosensitizer for Scavenger-Less Water Photo Splitting: New Insight in Green Hydrogen Technology

Nasser A M Barakat et al. Polymers (Basel). .

Abstract

In this study, hydrogen generation was performed by utilizing methylene blue dye as visible-light photosensitizer while the used catalyst is working as a transfer bridge for the electrons to H+/H2 reaction. Silica NPs-incorporated TiO2 nanofibers, which have a more significant band gap and longer electrons lifetime compared to pristine TiO2, were used as a catalyst. The nanofibers were prepared by electrospinning of amorphous SiO2 NPs/titanium isopropoxide/poly (vinyl acetate)/N, N-dimethylformamide colloid. Physicochemical characterizations confirmed the preparation of well morphology SiO2-TiO2 nanofibers with a bandgap energy of 3.265 eV. Under visible light radiation, hydrogen and oxygen were obtained in good stoichiometric rates (9.5 and 4.7 mL/min/gcat, respectively) without any considerable change in the dye concentration, which proves the successful exploitation of the dye as a photosensitizer. Under UV irradiation, SiO2 NPs incorporation distinctly enhanced the dye photodegradation, as around 91 and 94% removal efficiency were obtained from TiO2 nanofibers containing 4 and 6 wt% of the used dopant, respectively, within 60 min.

Keywords: electrospinning; hydrogen; photosensitizer; silica nanoparticles; water photo splitting.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Conceptual illustration for the electron transfer mechanisms in the heterogeneous catalytic reactions. (A). direct electron transfer mechanism, (B). Sensitizer-assisted electron transfer mechanism and (C). Photocatalyst-assisted electron transfer mechanism.
Figure 2
Figure 2
Schematic diagram for SiO2 NPs–incorporated TiO2 nanofibers synthesis process.
Figure 3
Figure 3
XRD pattern for the produced SiO2 NPs-incorporated TiO2 nanofibers.
Figure 4
Figure 4
EDX analysis for the produced SiO2 NPs–incorporated TiO2 nanofibers. The inset table displays the elemental analysis data, and the image represents the FE SEM result.
Figure 5
Figure 5
Normal; (A) and high resolution; (B) TEM images for the produced nanofibers. The inset represents the SAED result.
Figure 6
Figure 6
UV-vis. spectra for SiO2 NPs, and pristine and SiO2–incorporated TiO2 nanofibers (A); and Tauc plots for determination the bandgap energies for the pristine and SiO2–incorporated TiO2 nanofibers ((B) and (C), respectively).
Figure 7
Figure 7
Natural methylene blue dye removal rate (UV only) and in the presence of the prepared nanofibers photocatalysts under U.V. irradiation; (A), and linear plot of Ln(C/C0) vs. time for the photocatalytic degradation results using SiO2–incorporated TiO2 nanofibers; (B).
Figure 8
Figure 8
Hydrogen and oxygen production rates under visible light irradiation using SiO2–incorporated TiO2 nanofibers (6 wt% sample) and methylene blue as photosensitizer; (A), and dye photodegradation rate during the water splitting process; (B).
Figure 9
Figure 9
Conceptual illustration for the mechanism of water splitting under visible light radiation using methylene blue dye as a photosensitizer.
Figure 10
Figure 10
Conceptual illustration for the mechanism of methylene blue dye photo degradation under UV light irradiation using the prepared SiO2–incoportaed TiO2 nanofibers as photocatalyst.
See this image and copyright information in PMC

References

    1. Morrison S.R. The Chemical Physics of Surfaces. Springer Science & Business Media; New York, NY, USA: 2013.
    1. White J.L., Baruch M.F., Pander J.E., III, Hu Y., Fortmeyer I.C., Park J.E., Zhang T., Liao K., Gu J., Yan Y. Light-driven heterogeneous reduction of carbon dioxide: Photocatalysts and photoelectrodes. Chem. Rev. 2015;115:12888–12935. doi: 10.1021/acs.chemrev.5b00370. - DOI - PubMed
    1. Kampouri S., Stylianou K.C. Dual-functional photocatalysis for simultaneous hydrogen production and oxidation of organic substances. ACS Catal. 2019;9:4247–4270. doi: 10.1021/acscatal.9b00332. - DOI
    1. Kaliakin D.S., Fedorov D.G., Alexeev Y., Varganov S.A. Locating minimum energy crossings of different spin states using the fragment molecular orbital method. J. Chem. Theory Comput. 2019;15:6074–6084. doi: 10.1021/acs.jctc.9b00641. - DOI - PubMed
    1. Linkous C.A., Huang C., Fowler J.R. UV photochemical oxidation of aqueous sodium sulfide to produce hydrogen and sulfur. J. Photochem. Photobiol. A. 2004;168:153–160. doi: 10.1016/j.jphotochem.2004.03.028. - DOI

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