Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 1Citation - Scopus: 1Thickness-Dependent Characteristics and Oxidation of 2d-Cadmium(Royal Soc Chemistry, 2024) Gulucu, Arda; Sahin, HasanIn this study, the structural, electronic, and vibrational properties of the thinnest crystal structure that can be obtained by thinning bulk Cd down to a monolayer are investigated by performing first-principles calculations. Total energy optimization and dynamic stability calculations reveal that the single layer crystal structure has a hexagonal unitcell with a two-atomic basis where alternating layers are formed by trigonal arrangements of Cd atoms. Softening occurs with decreasing zone center optical phonon frequencies as a result of structural relaxation when going from a bulk to a single layer (SL) structure. It is also shown that the thinnest structure obtained from bulk Cd crystals maintains its metallic features despite the dimensional crossover. In addition, it is predicted through calculations that the SL Cd crystal strongly interacts with oxygen and that the oxidized regions even undergo chemical transformation to form a CdO crystal. In the double-layer CdO crystal resulting from the oxidation of individual Cd layers, the layers are connected to each other with partially covalent bonds, and this structure is a semiconductor with a band gap of 2.10 eV. On the one hand, the robust metallic structure of the thinnest possible Cd crystal provides flexibility for its use in nanoscale applications, on the other hand, the fact that its electronic properties can be changed by oxidation is important for optoelectronic device applications. In this study, the structural, electronic, and vibrational properties of the thinnest crystal structure that can be obtained by thinning bulk Cd down to a monolayer are investigated by performing first-principles calculations.Article Citation - WoS: 1Citation - Scopus: 1Experimental and Theoretical Investigation of Synthesis and Properties of Dodecanethiol-Functionalized Mos<sub>2</Sub>(Royal Soc Chemistry, 2023) Duran, Tuna A.; Şahin, Hasan; Sabani, Denis; Milosevic, Milorad V.; Sahin, HasanHerein, we investigate the DDT (1-dodecanethiol) functionalization of exfoliated MoS2 by using experimental and theoretical tools. For the functionalization of MoS2, DDT treatment was incorporated into the conventional NMP (N-methyl pyrrolidone) exfoliation procedure. Afterward, it has been demonstrated that the functionalization process is successful through optical, morphological and theoretical analysis. The D, G and 2LA peaks seen in the Raman spectrum of exfoliated NMP-MoS2 particles, indicate the formation of graphitic species on MoS2 sheets. In addition, as the DDT ratio increases, the vacant sites on MoS2 sheets diminish. Moreover, at an optimized ratio of DDT-NMP, the maximum number of graphitic quantum dots (GQDs) is observed on MoS2 nanosheets. Specifically, the STEM and AFM data confirm that GQDs reside on the MoS2 nano-sheets and also that the particle size of the DDT-MoS2 is mostly fixed, while the NMP-MoS2 show many smaller and distributed sizes. The comparison of PL intensities of the NMP-MoS2 and DDT-MoS2 samples states a 10-fold increment is visible, and a 60-fold increment in NIR region photoluminescent properties. Moreover, our results lay out understanding and perceptions on the surface and edge chemistry of exfoliated MoS2 and open up more opportunities for MoS2 and GQD particles with broader applications.