| 1. |
- Al Alawai, Reem, et al.
(författare)
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Role of bonding mechanisms during transfer hydrogenation reaction on heterogeneous catalysts of platinum nanoparticles supported on zinc oxide nanorods
- 2016
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; , s. 200-206
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Tidskriftsartikel (refereegranskat)abstract
- For supported heterogeneous catalysis, the interface between a metal nanoparticle and the support plays an important role. In this work the dependency of the catalytic efficiency on the bonding chemistry of platinum nanoparticles supported on zinc oxide (ZnO) nanorods is studied. Platinum nanoparticles were deposited on ZnO nanorods (ZnO NR) using thermal and photochemical processes and the effects on the size, distribution, density and chemical state of the metal nanoparticles upon the catalytic activities are presented. The obtained results indicate that the bonding at Pt-ZnO interface depends on the deposition scheme which can be utilized to modulate the surface chemistry and thus the activity of the supported catalysts. Additionally, uniform distribution of metal on the catalyst support was observed to be more important than the loading density. It is also found that oxidized platinum Pt(IV) (platinum hydroxide) provided a more suitable surface for enhancing the transfer hydrogenation reaction of cyclohexanone with isopropanol compared to zero valent platinum. Photochemically synthesized ZnO supported nanocatalysts were efficient and potentially viable for upscaling to industrial applications.
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| 2. |
- Al-Hamdi, Abdullah M., et al.
(författare)
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Efficient photocatalytic degradation of phenol in aqueous solution by SnO2:Sb nanoparticles
- 2016
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 370, s. 229-236
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Tidskriftsartikel (refereegranskat)abstract
- Photodegradation of phenol in the presence of tin dioxide (SnO2) nanoparticles under UV light irradiation is known to be an effective photocatalytic process. However, phenol degradation under solar light is less effective due to the large band gap of SnO2. In this study antimony (Sb) doped tin dioxide (SnO2) nanoparticles were prepared at a low temperature (80 degrees C) by a sol-gel method and studied for its photo catalytic activity with phenol as a test contaminant. The catalytic degradation of phenol in aqueous media was studied using high performance liquid chromatography and total organic carbon measurements. The change in the concentration of phenol affects the pH of the solution due to the by-products formed during the photo-oxidation of phenol. The photoactivity of SnO2:Sb was found to be a maximum for 0.6 wt.% Sb doped SnO2 nanoparticles with 10 mg L-1 phenol in water. Within 2 h of photodegradation, more than 95% of phenol could be removed under solar light irradiation.
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| 3. |
- Laxman, Kunjali Karthik, et al.
(författare)
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Supported versus colloidal zinc oxide for advanced oxidation processes
- 2017
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Ingår i: Applied Surface Science. - : Elsevier B.V.. - 0169-4332 .- 1873-5584. ; 411, s. 285-290
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Tidskriftsartikel (refereegranskat)abstract
- Photocatalysis is a green technology which typically utilizes either supported or colloidal catalysts for the mineralization of aqueous organic contaminants. Catalyst surface area and surface energy are the primary factors determining its efficiency, but correlation between the two is still unclear. This work explores their relation and hierarchy in a photocatalytic process involving both supported and colloidal catalysts. In order to do this the active surface areas of supported zinc oxide nanorods (ZnO NR's) and colloidal zinc oxide nanoparticles (having different surface energies) were equalized and their phenol oxidation mechanism and capacity was analyzed. It was observed that while surface energy had subtle effects on the oxidation rate of the catalysts, the degradation efficiency was primarily a function of the surface area; which makes it a better parameter for comparison when studying different catalyst forms of the same material. Thus we build a case for the use of supported catalysts, wherein their catalytic efficiency was tested to be unaltered over several days under both natural and artificial light, suggesting their viability for practical applications.
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| 4. |
- Myint, M. T. Z., et al.
(författare)
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Hydrophobic/hydrophilic switching on zinc oxide micro-textured surface
- 2013
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 264, s. 344-348
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Tidskriftsartikel (refereegranskat)abstract
- Switchable wettability of zinc oxide (ZnO) microrod coated surfaces was controlled in two different ways: (1) by physical geometry (surface coverage area SA: the area covered by solid) and (2) by irradiation with ultraviolet (UV) light followed by infrared (IR) or furnace heating. In the first approach, the threshold coverage area for achieving hydrophobic surfaces was found to be <40%, which is in good agreement with predicted values in the literature leading to a metastable Cassie-Baxter regime. The transformation of hydrophobic to hydrophilic surfaces was studied by alternating cycles of 3 h exposure to ultraviolet (λpeak ∼ 253 nm) light followed by 1 h of annealing or IR irradiation alone. Three different annealing temperatures (120 °C, 200 °C and 250 °C) were utilized. Results of this work can be applied for designing surfaces with controlled wettability.
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