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Article Citation - WoS: 2Citation - Scopus: 2Investigation of Tungsten-Based Seleno-Chevrel Compounds With Different Compositions for Efficient Water Splitting(Wiley-v C H verlag Gmbh, 2023) Dag, Tugce Sevinc; Surucu, Gokhan; Gencer, Aysenur; Surucu, Ozge; Ozel, Faruk; Ciftci, YaseminThis study investigates the photocatalytic water splitting performance for NixW6Se8(x=1,2,3,4)${\mathrm{N}}{{\mathrm{i}}_{\mathrm{x}}}{{\mathrm{W}}_6}{\mathrm{S}}{{\mathrm{e}}_8}\;( {x = 1, 2, 3, 4} )$ Chevrel phases with the chemical formula M(x)Mo(6)Ch(8), where M is a metal and Ch is a chalcogen, with x being 0, 1, 2, 3, or 4. Density Functional Theory (DFT) is used to study the NixW6Se8(x=1,2,3,4)${\mathrm{N}}{{\mathrm{i}}_{\mathrm{x}}}{{\mathrm{W}}_6}{\mathrm{S}}{{\mathrm{e}}_8}{\mathrm{\;}}( {x = 1, 2, 3, 4} )$ Chevrel phases, which includes earth-abundant elements for this specific study as an essential consideration for photocatalytic water splitting. The electronic properties are calculated for the NiW6Se8 and Ni2W6Se8 compounds with thermodynamical, mechanical, and dynamic stabilities. For photocatalytic water splitting, the band gaps below 1.23 eV are excluded, and the conduction and valence band levels are determined to examine the reduction and oxidation potentials for efficient photocatalytic water-splitting materials. An examination of the selected band gaps, along with the conduction and valence band levels, reveals that NiW6Se8 is suitable for both reduction and oxidation reactions; whereas, Ni2W6Se8 is a convenient material only for the reduction reaction. This is the first attempt, as far as the literature reveals, to study Chevrel phases in detail and to identify a suitable compound for photocatalytic water splitting.Article Citation - WoS: 35Citation - Scopus: 35Invisible Thin-Film Patterns With Strong Infrared Emission as an Optical Security Feature(Wiley-v C H verlag Gmbh, 2018) Bakan, Gokhan; Ayas, Sencer; Serhatlioglu, Murat; Elbuken, Caglar; Dana, AykutluSpectrally selective thermal emission is in high demand for thermophotovoltaics, radiative cooling, and infrared sensing applications. Spectral control of the emissivity is historically achieved by choosing the material with suitable infrared properties. The recent advancements in nanofabrication techniques that lead to enhanced light-matter interactions enable optical properties like infrared emissivity that are not naturally available. In this study, thermal emitters based on nanometer-thick dielectrics on field-enhancement surfaces as optical security features are proposed. Such a function is achieved by generating patterns by ultrathin dielectrics that are transparent in the visible and exhibit strong infrared absorption in the spectral range of thermal cameras. The invisible patterns are then revealed by thermal imaging. The field-enhancement surfaces enhance the emissivity of the patterns, in turn reduce the minimum temperature to detect the thermal emission down to approximate to 30 degrees C from >150 degrees C to exploit ubiquitous heat sources like the human body. The study provides a framework for the use of thermal emitters as optical security features and demonstrates applications on rigid and flexible substrates.Article Citation - WoS: 3Citation - Scopus: 2Establishing the nimo6se8< Chevrel Phase as a Promising Material Using Dft(Wiley-v C H verlag Gmbh, 2024) Surucu, Gokhan; Surucu, Ozge; Usanmaz, Demet; Oezel, Faruk; Gencer, AysenurIn this study, the NiMo6Se8 Chevrel phase is analyzed using Density Functional Theory (DFT) and the Vienna Ab-initio Simulation Package (VASP). The analysis focuses on the phase's structural, electrical, and mechanical characteristics to fill gaps in the current literature. The presence of a rhombohedral crystal structure confirms its thermodynamic stability, as indicated by a negative formation enthalpy, which suggests that it can be synthesized under favorable conditions. The electronic properties of the phase are analyzed, indicating that it exhibits semiconductor characteristics with a bandgap of 1.07 eV. This makes it appropriate for various technological applications. The estimated elastic constants provide an indication of mechanical strength and flexibility, with a noticeable presence of anisotropic elasticity. The confirmation of dynamical stability is achieved by analyzing the phonon dispersion curve, which reveals the absence of any negative frequencies. Furthermore, the material has a low thermal conductivity, increasing its suitability for thermoelectric applications. The analysis emphasizes the versatile capabilities of the NiMo6Se8 Chevrel phase, especially in thermoelectric and energy storage applications, showcasing its promising potential for future technological implementation.Article Citation - WoS: 143Citation - Scopus: 149A Novel Neutral State Green Polymeric Electrochromic With Superior N- and P-Doping Processes: Closer To Red-Blue (rgb) Display Realization(Wiley-v C H verlag Gmbh, 2008) Cihaner, Atilla; Algi, FatihTwo donor-acceptor systems, 4,7-di-2-thienyl-2,1,3-benzoselenadiazole (TSeT) and 4,7-di-2,3-dehydrothieno[3,4-b][1,4]dioxin-5yl-2,1,3-benzoselenadiazole (ESeE) are synthesized and electropolymerized to give polymers PTSeT and PESeE, respectively. One of the polymers, PTSeT, is blue-green in the neutral state and soluble, exhibiting a deep-red emission color. The other, PESeE, is the first 2,1,3-benzoselenadiazole-based neutral state green polymer with a narrow bandgap (1.04eV). Furthermore, PESeE has superior and durable n- and p-doping processes. Beyond the stability and the robustness, both of the polymer films exhibit multi-electrochromic behavior.
