Characterization of Colloidal Quantum Dot Ligand Exchange by X-ray Photoelectron Spectroscopy

Atewologun, Ayomide; Ge, Wangyao

doi:10.1007/s11664-012-2371-4

Cited by 7 publications

(3 citation statements)

References 20 publications

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“…The spectrum shows a strong C1s peak confirming the presence of carbon due to the capping agent on the surface of the nanostructures. The attribution of the carbon peak to the capping agent is consistent with other reported work on capped nanoparticles and XPS has in fact been used to trace ligand exchange on the surface of the nanocrystals [20,21]. The O1s peak is attributed to the oxidation of the capping agent due to the adsorption of oxygen from the atmosphere.…”

Section: Resultssupporting

confidence: 86%

Elucidating the structural properties of gold selenide nanostructures

et al. 2019

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Section: Resultssupporting

confidence: 86%

Elucidating the structural properties of gold selenide nanostructures

et al. 2019

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“…The successful capping of the nanoflowers by the organic ligand OLA was confirmed by the presence of the strong C 1s peak. Atewolegun et al used XPS in their studies to confirm the success of ligand exchange on colloidal quantum dots [30]. The capping of the samples is further confirmed by the large carbon composition (77.4%) of the sample, as seen in Table 1.…”

Section: Characterization Of Ws 2 Nanoflowersmentioning

confidence: 93%

Hierarchical Nanoflowers of Colloidal WS2 and Their Potential Gas Sensing Properties for Room Temperature Detection of Ammonia

et al. 2021

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A one-step colloidal synthesis of hierarchical nanoflowers of WS2 is reported. The nanoflowers were used to fabricate a chemical sensor for the detection of ammonia vapors at room temperature. The gas sensing performance of the WS2 nanoflowers was measured using an in-house custom-made gas chamber. SEM analysis revealed that the nanoflowers were made up of petals and that the nanoflowers self-assembled to form hierarchical structures. Meanwhile, TEM showed the exposed edges of the petals that make up the nanoflower. A band gap of 1.98 eV confirmed a transition from indirect-to-direct band gap as well as a reduction in the number of layers of the WS2 nanoflowers. The formation of WS2 was confirmed by XPS and XRD with traces of the oxide phase, WO3. XPS analysis also confirmed the successful capping of the nanoflowers. The WS2 nanoflowers exhibited a good response and selectivity for ammonia.

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“…The presence of the carbon peak is attributed to the capping agent; this is consistent with other published work on capped nanoparticles. XPS has been used previously to trace ligand exchange on the surface of the nanocrystals [24,25]. The oxygen is due to both the presence of WO3 and the oxidation of the capping agent.…”

Section: Characterization Of Ola/ws2 Nanostructuresmentioning

confidence: 99%

Limiting the Oxidation of WS2 Nanostructures by Oleylamine Surface Passivation for Room Temperature NH3 Sensing

Gqoba¹,

Rodrigues²,

Mphahlele³

et al. 2020

Preprint

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Oleylamine capped WS2 nanostructures were successfully formed at 320 °C via a relatively simple colloidal route. SEM and TEM analyses showed that the 3D nanoflowers that were initially formed disintegrated into 2D nanosheets after prolonged incubation. XPS and XRD analyses confirmed oxidation of WS2 into WO3. Sensors based on these oleylamine capped WS2 nanoflowers and nanosheets still showed a change in electrical response towards various concentrations of NH3 vapour at room temperature in a 25% relative humidity background despite the oxidation. The nanoflowers exhibited n-type response while the nanosheets displayed a p-type response towards NH3 exposure. The nanoflower based sensors showed better response to NH3 vapour exposure than the nanosheets. The sensors showed a good selectivity towards NH3 relative to acetone, ethanol, chloroform and toluene. Meanwhile, a strong interference of humidity to the NH3 response was displayed at high relative humidity levels. The results demonstrated that oleylamine limited the extent of oxidation of WS2 nanostructures. The superior sensing performance of the nanoflowers can be attributed to their hierarchical morphology which enhances the surface area and diffusion of the analyte.

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Characterization of Colloidal Quantum Dot Ligand Exchange by X-ray Photoelectron Spectroscopy

Cited by 7 publications

References 20 publications

Elucidating the structural properties of gold selenide nanostructures

Elucidating the structural properties of gold selenide nanostructures

Hierarchical Nanoflowers of Colloidal WS2 and Their Potential Gas Sensing Properties for Room Temperature Detection of Ammonia

Limiting the Oxidation of WS2 Nanostructures by Oleylamine Surface Passivation for Room Temperature NH3 Sensing

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