Journal of NanoScience in Advanced Materials

Theoretical Computation of Structural Properties and Electronic Band Gap of CsGeCl3 Perovskite: A DFT-based Simulation

Merve Özcan — Fri, 22 Dec 2023 00:00:00 +0300

This study aimed to explore the structural properties and electronic band gap of CsGeCl3 with cubic structure (Pm-3m space group, No.221). Based on the density functional theory (DFT), all calculations were performed using Ultra Soft Pseudo Potential (USPP) type potential in generalized gradient approach (GGA) with Perdew-Burke-Ernzorhof (PBE) for exchange-correlation function, as implemented in the QUANTUM ESPRESSO code. The primitive cell was used in all calculations for predicting the physical properties of solids. The computation results were compared with available literature data. It was found that the structural properties of the compound were compatible with other reported results. To understand the nature bond of the chemical bond, the bond lengths of Cs-Cl and Ge-Cl atoms were calculated. The electronic band structure was calculated along the high symmetry points (Γ-X-M-R- Γ) using an optimized geometry structure.

In situ Synthesis of 2D Bismuth/Graphitic Carbon Nitride Heterojunctions for the Visible Light-Driven Organic Dye Degradation

Buse Sündü, Ayben Türkkan, Zafer EROĞLU, Onder Metin — Fri, 22 Dec 2023 00:00:00 +0300

In this study, highly efficient photocatalysts were developed by synthesizing binary heterojunctions of 2D Bismuth/Graphitic Carbon Nitride (2D Bi/gCN) in various ratios through a facile in situ synthesis method. Advanced analytical techniques were used to characterize the yielded heterojunctions, and their photocatalytic performance was evaluated in the Methyl Orange (MO) degradation under visible light irradiation. The 2D Bi/gCN heterojunctions provided exceptional photoactivity under visible light illumination, leading to the significantly higher degradation efficiency compared to pristine gCN. To clarify the high photocatalytic dye degradation activity of 2D Bi/gCN heterojunctions, a band diagram that depicts the dynamics of electron-hole migration between the gCN and 2D Bi in the heterojunction structure revealed the formation of a type-I heterojunction. The photophysical and structural characteristics of the 2D Bi/gCN heterojunctions were assessed by utilizing different approaches to authenticate the effective integration of 2D Bi into gCN layers. The 2D Bi/gCN heterojunctions exhibit enhanced light absorption and improved charge separation, with the 2D Bi_0.06/gCN composition exhibiting the highest photocatalytic performance, achieving 61% MO photodegradation efficiency in 30 min. Kinetic analysis demonstrated that the 2D Bi_0.06/gCN composition degraded MO at a rate 2.04 times higher than pristine gCN. Overall, the 2D Bi/gCN heterojunctions showed promising photocatalytic properties with the 2D Bi_0.06/gCN heterojunctions emerging as an exceptionally efficient photocatalyst for MO degradation under visible light illumination. This research contributes to the understanding and application of 2D Bi/gCN heterojunctions as photocatalysts in the development of other sustainable chemical processes.

Chemical and Physical Stability of Carbon Quantum Dots Synthesized from Mahonia aquifolium

Beyhan TAHTA, Ali Burak Sünbül, Serhan Uruş — Fri, 22 Dec 2023 00:00:00 +0300

Carbon quantum dots (CQDs); It is among the most popular carbon-based nanomaterials of recent years due to its low toxicity, eco-friendly nature as opposed to chemically derived carbon nanomaterials, high biocompatibility, easy water solubility, short synthesis time, low cost, and tunable fluorescence properties. In this study, quantum dots were synthesized by the hydrothermal method using Yellow Paint Bush (Mahonia aquifolium) and citric acid as carbon sources. The synthesized CQDs were characterized by using Fourier-transform infrared spectroscopy (FT-IR), photoluminescence spectroscopy (PL), UV–Vis spectroscopy, X-Ray diffraction (XRD), thermal analysis (TG/DTA/DTG). Stability of carbon quantum dots (on the 1st, 5th, 10th, 15th, 20th and 30th days) in the refrigerator, at room conditions, in the dark, and moreover in the UV cabinet at 365 nm wavelength (between 0 and 30 minutes and 1-7 hours). ) and pH (pH=5-12) dependent emission properties were investigated.

Impacts of Fe and Ru Atomic Dopants on the Structural and Electronic Features of a Graphene Flake: DFT Outlook

Muhammad Da'i, Osman Murat Ozkendir, Mahmoud Mirzaei — Fri, 22 Dec 2023 00:00:00 +0300

Density functional theory (DFT) calculations were performed for investigating the impacts of iron (Fe) and ruthenium (Ru) on the structural and electronic features of a graphene (Gr) flake for providing insights into the customization of nanostructures for desired purposes. The results indicated a planar stability for each of FeGr and RuGr models, in which the central area of both models were wider than the pure Gr model. Additionally, the electronic molecular orbital features indicated the variations of frontier molecular orbital levels in the atomic doped models but with different changes for the FeGr and RuGr models in comparison with the pure Gr model. While the FeGr model was proposed to work as a better conductor in comparison with the pure Gr, the RuGr model was proposed to work as a batter capacitor. Variation of molecular orbitals of both models were significant to be monitored by the diagrams of density of states (DOS) and their quantitative values indicated characteristic and unique features for the doped models. Finally, the features of FeGr and RuGr customized them for the specific applications of better conductors of better capacitors.

Modelling the Magnetocaloric Effect Arising from Critical Behavior of Tb2Rh3Ge Rare-Earth

Salha Khadhraoui, Nadia Zaidi, Hanen Hammami — Fri, 22 Dec 2023 00:00:00 +0300

In this paper, we investigated the critical behavior during the transition from the ferromagnetic to paramagnetic phase in Tb2Rh3Ge rare-earth. Utilizing the Landau theory, we produced isothermal magnetization curves, M(H,T), in the vicinity of the ferromagnetic-to-paramagnetic phase transition. Through an iterative program utilizing the Kouvel-Fisher method, we determined the optimized critical exponents to be: γ=1.003; β=0.348. These critical exponents are clear and reasonably consistent, although they do not align with the conventional universality classes. We have successfully simulated the magnetic entropy change curves by combining the Arrott-Noakes equation with the Landau model.