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

Abstract

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.

Colloidal Synthesis of Zirconium Disulphide Nanostructures and their Stability Against Oxidation

“…The surface oxidation of TMDCs has been reported by many authors; the other oxygen peaks can be ascribed to the oxidation of the ligand used during the synthesis. A similar finding has been reported in our group [19,21] . The C1s peak also has 3 peaks at 284.6 eV, 286.3 eV and 288.1 eV which are ascribed to C−C, C−O and O−C=O respectively.…”

“…A similar finding has been reported in our group. [19,21] The C1s peak also has 3 peaks at 284.6 eV, 286.3 eV and 288.1 eV which are ascribed to CÀ C, CÀ O and OÀ C=O respectively. The highest peak is CÀ C bonds from the alkyl group of OA, the CÀ O and OÀ C=O are as a result of the oxidation of the ligand.…”

“…Colloidal synthesis of other 2D nanomaterials is relatively simpler. The Moloto group has fabricated several 2D nanomaterials including InSe, In 2 S 3 , AuSe, MoSe 2 and WS 2 among many others using the colloidal method of synthesis [17–21] . This method also provided the Moloto group an avenue to fabricate hierarchical nanostructures in the form of nanoflowers of MoSe 2, NbSe 2 and WS 2 by varying the reaction parameters.…”

Microjunction-Modulated Selective Ammonia Sensor with P-Type Oxides-Decorated WS2 Microflakes

“…The transition metal dichalcogenides (TMDs) have gained tremendous attention because of their unique two-dimensional nanostructures. , The TMDs have the advantages of larger specific surface area, thereby promoting the gas adsorption ability and possibly owning good gas sensing properties . Among them, WS 2 shows a potential to be developed for a low temperature chemical gas sensors . It has a tunable narrow band gap from 1 to 2 eV, good optoelectronic, thermal, and mechanical stability .…”

“…8 Among them, WS 2 shows a potential to be developed for a low temperature chemical gas sensors. 9 It has a tunable narrow band gap from 1 to 2 eV, good optoelectronic, thermal, and mechanical stability. 10 (RT).…”