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Author: search.filters.author.Seeharaj, PanpailinSubject: search.filters.subject.composite

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    Magnetically separable CeO2/CoFe2O4 heterojunction photocatalysts for dye degradation: characterization and mechanism
    (2024-01-01)
    Seeharaj, Panpailin
    ;
    Pasupong, Patchara
    ;
    Choojun, Kittisak
    This study developed magnetically separable CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> heterojunction photocatalysts for dye degradation to reduce water pollution. The CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> nanocomposites with different CeO<inf>2</inf> ratios (10, 20, and 30 wt%) were prepared by a precipitation method. The nanocrystalline 20%CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> photocatalyst with a surface area of 117 m<sup>2</sup>.g<sup>−1</sup>, E<inf>g</inf> 2.37 eV, and uniform distribution of quasi-spherical CeO<inf>2</inf> minor phase (cubic fluorite structure with particle size 3 ± 1 nm) throughout the distorted spherical CoFe<inf>2</inf>O<inf>4</inf> major phase (cubic spinel structure with particle size 9 ± 3 nm) showed the best photocatalytic performance for methylene blue (MB) degradation under UV light irradiation at the efficiency of 88.7% and the apparent rate constant (k) of 0.0138 min<sup>−1</sup>. The 20%CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> photocatalyst had a good magnetic response and could be easily separated from the dye solution by applying an external magnetic field. The reusability test showed lower photodegradation efficiency due to the adsorption of residual MB dye on the photocatalyst surface. The formation of heterojunction at the interfaces of CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> facilitated the photogenerated charge separation and increased availability of active species of holes (h<sup>+</sup>) and hydroxy radicals (<sup>∙</sup>OH), which were the key factors in improving the photocatalytic activity.
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    CeO2/CuO/TiO2heterojunction photocatalysts for conversion of CO2to ethanol
    (2021-09-10)
    Seeharaj, Panpailin
    ;
    Vittayakorn, Naratip
    ;
    Morris, John
    ;
    Kim-Lohsoontorn, Pattaraporn
    An attempt to reduce CO2 emissions has led to the development of CeO2/CuO/TiO2 heterojunction photocatalysts for photoconversion of CO2 to useful products, e.g. ethanol. Composite photocatalysts were simply prepared by mixing TiO2 (P25) with different mass ratios of CeO2 (1 wt%) and CuO (2 or 3 wt%) by ball milling. The prepared photocatalysts had uniformly distributed CeO2 and CuO phases, throughout the TiO2 phase. The integration of CeO2 and CuO into TiO2 at 1 wt% CeO2 and 3 wt% CuO produced a composite, with a reduced band gap of 2.88 eV, allowing absorption of lower energy light and a lower electron-hole recombination rate. The 1%CeO2/3%CuO/TiO2 photocatalysts yielded ethanol at 30.5 μmol gcat-1 h-1, almost three times higher than the yield from pure TiO2. This improved CO2 conversion efficiency was due to contributions from properties of both additives: CeO2 increased light absorption, while CuO acted as an electron trap and enhanced CO2 adsorption. In addition, the heterojunction at the interfaces facilitated the photogenerated charge separation, which, in turn, increased the charge participation in the catalyzed conversion reactions.