CO Oxidation Activities of Ni and Pd-TiO<sub>2</sub>@SiO<sub>2</sub>Core-Shell Nanostructures

Abstract:A formic acid modified catalyst, Co 3 O 4 -CeO 2 , was prepared via facile urea-hydrothermal method and applied in CO oxidation. The Co 3 O 4 -CeO 2 -0.5 catalyst, treated by formic acid at 0.5 mol/L, performed better in CO oxidation with T 50 obtained at 69.5˝C and T 100 obtained at 150˝C, respectively. The characterization results indicate that after treating with formic acid, there is a more porous structure within the Co 3 O 4 -CeO 2 catalyst; meanwhile, despite of the slightly decreased content of Co, there are more adsorption sites exposed by acid treatment, as suggested by CO-TPD and H 2 -TPD, which explains the improvement of catalytic performance.

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“…Low temperature oxidation of carbon monoxide is considered to be the most efficient and cost-effective method for removal of CO [1,2].…”

Section: Introductionmentioning

confidence: 99%

Formic Acid Modified Co3O4-CeO2 Catalysts for CO Oxidation

et al. 2016

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“…According to the results obtained, the symmetric and asymmetric stretching modes of the Si-O-Si bond are visible around 790 and 1110 cm −1 . These two peaks are observed for SiO 2 and all SiO 2 @TiO 2 samples, indicating that the TiO 2 coating thickness is thin enough to detect the IR absorption signal from the core SiO 2 [ 33 , 34 , 35 ]. However, it is also possible to observe the intensity of the Si-O-Si bond as being higher than calcined SiO 2 @TiO 2 compared to the hydrothermal samples, which can be explained by the thickness of the TiO 2 shell being lower for the calcined sample compared to the hydrothermal samples, according to the previous conclusion.…”

Section: Resultsmentioning

confidence: 99%

Development and Upscaling of SiO2@TiO2 Core-Shell Nanoparticles for Methylene Blue Removal

et al. 2023

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SiO2@TiO2 core-shell nanoparticles were successfully synthesized via a simple, reproducible, and low-cost method and tested for methylene blue adsorption and UV photodegradation, with a view to their application in wastewater treatment. The monodisperse SiO2 core was obtained by the classical Stöber method and then coated with a thin layer of TiO2, followed by calcination or hydrothermal treatments. The properties of SiO2@TiO2 core-shell NPs resulted from the synergy between the photocatalytic properties of TiO2 and the adsorptive properties of SiO2. The synthesized NPs were characterized using FT-IR spectroscopy, HR-TEM, FE–SEM, and EDS. Zeta potential, specific surface area, and porosity were also determined. The results show that the synthesized SiO2@TiO2 NPs that are hydrothermally treated have similar behaviors and properties regardless of the hydrothermal treatment type and synthesis scale and better performance compared to the SiO2@TiO2 calcined and TiO2 reference samples. The generation of reactive species was determined by EPR, and the photocatalytic activity was evaluated by the methylene blue (MB) removal in aqueous solution under UV light. Hydrothermally treated SiO2@TiO2 showed the highest adsorption capacity and photocatalytic removal of almost 100% of MB after 15 min in UV light, 55 and 89% higher compared to SiO2 and TiO2 reference samples, respectively, while the SiO2@TiO2 calcined sample showed 80%. It was also observed that the SiO2-containing samples showed a considerable adsorption capacity compared to the TiO2 reference sample, which improved the MB removal. These results demonstrate the efficient synergy effect between SiO2 and TiO2, which enhances both the adsorption and photocatalytic properties of the nanomaterial. A possible photocatalytic mechanism was also proposed. Also noteworthy is that the performance of the upscaled HT1 sample was similar to one of the lab-scale synthesized samples, demonstrating the potentiality of this synthesis methodology in producing candidate nanomaterials for the removal of contaminants from wastewater.

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