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EnglishThe C3N4 -based nanopowders prepared by thermal condensation of melamine (MCN) with subsequent thermal etching (MCN-TE) and H2O2 -treatment were investigated by Q- and X-band EPR spectroscopy in dark and upon in situ UVA or visible-light exposure. Lorentzian signal at g = 2.003, more pronounced in the case of the thermally etched material, dominates EPR spectra of MCN and MCN-TE. More complex spectra were found for H2O2 -treated photocatalysts revealing the presence of signals attributed to the radicals produced via H2O2 interaction with C/N sites in the C3N4 polymeric network. The X-band spectra monitored upon in situ irradiation of the C3N4 -based photocatalysts evidenced the intensity growth of the single line at g = 2.0033 indicating the photoinduced generation of electrons in localized paramagnetic states with the Curie dependence on temperature in the temperature range 100–180 K. The response towards UV or visible-light exposure was significantly limited in the case of H2O2 -treated photocatalysts. EPR spin trapping experiments performed in aqueous suspensions demonstrated the formation of HO2[rad] and HO [rad] spin-adducts, and the increased stability of the primary photogenerated O2 javax.xml.bind.JAXBElement@3a251187 – in aprotic media was well documented by the irradiation of the photocatalysts in the dimethylsulfoxide/water mixed solvent. The highest activities in the production of the non-persistent radical species spin-adducts were found for the thermally etched and pristine photocatalysts, confirming the negative effect of H2O2 -treatment.
| Data di pubblicazione: | 2019 |
| Titolo: | EPR investigations of polymeric and H2O2 -modified C3N4 -based photocatalysts |
| Autori: | |
| Citazione: | Dvoranova, D., Barbierikova, Z., Mazur, M., Garcia-Lopez, E., Marci, G., Luspai, K., et al. (2019). EPR investigations of polymeric and H2O2 -modified C3N4 -based photocatalysts. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. A, CHEMISTRY, 375, 100-113. |
| Rivista: | |
| Digital Object Identifier (DOI): | http://dx.doi.org/10.1016/j.jphotochem.2019.02.006 |
| Abstract: | The C3N4 -based nanopowders prepared by thermal condensation of melamine (MCN) with subsequent thermal etching (MCN-TE) and H2O2 -treatment were investigated by Q- and X-band EPR spectroscopy in dark and upon in situ UVA or visible-light exposure. Lorentzian signal at g = 2.003, more pronounced in the case of the thermally etched material, dominates EPR spectra of MCN and MCN-TE. More complex spectra were found for H2O2 -treated photocatalysts revealing the presence of signals attributed to the radicals produced via H2O2 interaction with C/N sites in the C3N4 polymeric network. The X-band spectra monitored upon in situ irradiation of the C3N4 -based photocatalysts evidenced the intensity growth of the single line at g = 2.0033 indicating the photoinduced generation of electrons in localized paramagnetic states with the Curie dependence on temperature in the temperature range 100–180 K. The response towards UV or visible-light exposure was significantly limited in the case of H2O2 -treated photocatalysts. EPR spin trapping experiments performed in aqueous suspensions demonstrated the formation of HO2[rad] and HO [rad] spin-adducts, and the increased stability of the primary photogenerated O2 javax.xml.bind.JAXBElement@3a251187 – in aprotic media was well documented by the irradiation of the photocatalysts in the dimethylsulfoxide/water mixed solvent. The highest activities in the production of the non-persistent radical species spin-adducts were found for the thermally etched and pristine photocatalysts, confirming the negative effect of H2O2 -treatment. |
| URL: | http://www.elsevier.com/locate/jphotochem |
| Settore Scientifico Disciplinare: | Settore CHIM/07 - Fondamenti Chimici Delle Tecnologie |
| Appare nelle tipologie: | 1.01 Articolo in rivista |
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http://hdl.handle.net/10447/362365
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