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    Enhanced photocatalytic hydrogen evolution from band-gap tunable Ag2S:X (X?=?Ni, Co, Zn, Mn) nanocrystals: Effect of transition metal ions
    (Elsevier B.V., 2020) Yanalak, Gizem; Sarılmaz, Adem; Karanfil, Gizem; Aslan, Emre; Ozel, Faruk; Hatay Patir, Imren
    In the present work, Ni, Co, Zn and Mn doped Ag2S nanocrystal catalysts were prepared via the hot-injection technique which is one of the top-down approach. The nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), diffuse reflectance spectroscopy (DRS), UV?vis spectroscopy (UV) and cyclic voltammetry (CV) to illuminate the crystal properties and the photocatalytic mechanism. The presence of doping each of the transition metals on Ag2S nanocrystals were tested for their performance in the photocatalytic hydrogen evolution from water containing TEOA and EY as a hole scavenger and photoabsorber, respectively. The results demonstrated that Ni, Co, Zn and Mn doped Ag2S nanocrystals were showed higher photocatalytic activity as compared with the Ag2S under visible light irradiation source. In addition, transition metal consisting Ag2S catalysts, which in view of the limited literatures, provides new insights for expanding the application of chalcogenide catalysts. © 2020 Elsevier B.V.
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    One Material-Opposite Triboelectrification: Molecular Engineering Regulated Triboelectrification on Silica Surface to Enhance TENG Efficiency
    (Mdpi, 2023) Arkan, Mesude Zeliha; Kinas, Zeynep; Yalcin, Eyup; Arkan, Emre; Ozel, Faruk; Karabiber, Abdulkerim
    Molecular engineering is a unique methodology to take advantage of the electrochemical characteristics of materials that are used in energy-harvesting devices. Particularly in triboelectric nanogenerator (TENG) studies, molecular grafting on dielectric metal oxide surfaces can be regarded as a feasible way to alter the surface charge density that directly affects the charge potential of triboelectric layers. Herein, we develop a feasible methodology to synthesize organic-inorganic hybrid structures with tunable triboelectric features. Different types of self-assembled monolayers (SAMs) with electron-donating and withdrawing groups have been used to modify metal oxide (MO) surfaces and to modify their charge density on the surface. All the synthetic routes for hybrid material production have been clearly shown and the formation of covalent bonds on the MO's surface has been confirmed by XPS. The obtained hybrid structures were applied as dopants to distinct polymer matrices with various ratios and fiberization processes were carried out to the prepare opposite triboelectric layers. The formation of the fibers was analyzed by SEM, while their surface morphology and physicochemical features have been measured by AFM and a drop shape analyzer. The triboelectric charge potential of each layer after doping and their contribution to the TENG device's parameters have been investigated. For each triboelectric layer, the best-performing tribopositive and tribonegative material combination was separately determined and then these opposite layers were used to fabricate TENG with the highest efficiency. A comparison of the device parameters with the reference indicated that the best tribopositive material gave rise to a 40% increase in the output voltage and produced 231 V, whereas the best tribonegative one led to a 33.3% rise in voltage and generated 220 V. In addition, the best device collected similar to 83% more charge than the reference device and came up with 250 V that corresponds to 51.5% performance enhancement. This approach paved the way by addressing the issue of how molecular engineering can be used to manipulate the triboelectric features of the same materials.
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    Photo-enhanced piezocatalytic hydrogen evolution using in situ silver piezodeposited scheelite-type BaMoO4 and BaWO4
    (Royal Soc Chemistry, 2023) Kuru, Talha; Sarilmaz, Adem; Aslan, Emre; Ozel, Faruk; Patir, Imren Hatay
    Piezocatalysis shows promise to diversify hydrogen production methods and solve problems in photocatalysis such as high charge recombination and low solar light absorption by waste mechanical energy. Scheelite type BaWO4 and BaMoO4 have been used in piezocatalytic hydrogen production due to their non-centrosymmetric crystal structure and piezoelectric and electrochemical properties for the first time. Piezocatalytic hydrogen production of BaMoO4 and BaWO4 was observed to be 198 and 313 mu mol g(-1) h(-1), respectively, under ultrasonic sound. In order to increase the piezocatalytic hydrogen production activities, in situ Ag piezodeposition was performed on BaMoO4 and BaWO4 catalyst surfaces, and the hydrogen production was found to be 365 and 469 mu mol g(-1) h(-1), respectively. Schottky junctions between BaWO4 and Ag (or BaMoO4 and Ag) enhanced the separation and migration of piezoelectric polarization charges formed on the non-centrosymmetric unit cells. Moreover, photopiezocatalytic hydrogen production of BaMoO4 and BaWO4 was investigated by application of both visible light irradiation and ultrasonic sound, and then it reached 789 and 1103 mu mol g(-1) h(-1), respectively. The bending of valence and conduction bands of BaWO4 and BaMoO4 occurs under mechanical stress, can lead to a reduced band gap energy. BaWO4 and BaMoO4 generate photoexcited charges under visible light illumination, providing support for the piezocatalytic hydrogen evolution reaction. The most enhanced hydrogen production rates were obtained under photopiezocatalytic conditions by using BaMoO4/Ag and BaWO4/Ag as 1560 and 2146 mu mol g(-1) h(-1), respectively. Piezocatalytic hydrogen production of piezocatalysts was examined for 6 hours under mechanical stress, and it was observed that piezocatalytic hydrogen production continued to increase significantly during the 6-hour reaction. In addition, reusability tests of piezocatalysts for hydrogen production were carried out and it was determined that all catalysts sustained meaningful stability throughout 6 cycles. These piezocatalytic hydrogen production activities among catalysts are confirmed by piezoresponse force microscopy, electrochemical impedance spectroscopy and chronoamperometry measurements. This study will pave the way for light induced piezocatalytic applications by different heterojunctions, nanocomposite catalysts etc.
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    Quaternary nanorods: promising versatile agents for cancer therapy, antimicrobial strategies and free radical neutralization
    (Taylor & Francis Inc, 2023) Ulusu, Funda; Sarilmaz, Adem; Ulusu, Yakup; Ozel, Faruk
    Cu2XSnS4 (CXTS; X: Zn, Mn or Co) nanorods (NRs) were prepared by a simple hot-injection method and their cytotoxic activities on human breast adenocarcinoma (MCF-7), metastatic melanoma (451Lu) and embryonic kidney (HEK-293) cell lines were investigated for the first time. The antibacterial activities of these nanoparticles on both gram-positive (S. aureus) and gram-negative (E. coli) pathogenic bacteria as well as their DPPH (2,2-diphenyl-1- picrylhydrazyl) scavenging activities were evaluated. The structural characterizations show that the obtained nanoparticles have the same crystal structure and are shaped as nanorods with an average 10-40 nm edge length. The data obtained in cytotoxicity studies revealed that the synthesized CXTS NRs have a significant inhibition effect, especially on cancer cell lines (MCF-7 and 451Lu), in a dose-dependent manner over a period of 24 h, demonstrating their potential for use as anticancer agents. In addition, the findings indicate that the synthesized nanorods possess strong antibacterial properties against the pathogenic microorganisms tested and display a marked antioxidant effect through efficient elimination of DPPH activity. This comprehensive study sheds light on the creation and development of CXTS NRs as promising versatile agents in various biomedical and environmental applications such as cancer therapy, antimicrobial strategies and the neutralization of free radicals.
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    Triboelectric Nanogenerator with Nanofiber Dielectric Layer Enriched through Novel Zinc Phthalocyanine Carrying Four O-Carboranyl Units
    (Wiley-V C H Verlag Gmbh, 2023) Ozen, Abdurrahman; Karabiber, Abdulkerim; Sener, Sevil; Ipek, Osman; Ozel, Faruk
    Triboelectric nanogenerator (TENG) technology is one of the new, low-cost, and simple methods used to convert mechanical energy into electrical energy. Despite having so many advantages, the energy efficiency of this technology is extremely low. Therefore, their current performance needs to be improved so that they can be used more in daily life. Nanofibers (NFs) are one of the most important material groups that can be used for this technology due to their large surface area-volume ratio, easy production, low cost, and simplicity. Herein, Nylon 6.6 and polyacrylonitrile are used as tribopositive and tribonegative dielectric layers, respectively. To increase the output performances of the TENG system, different weight ratios (1, 2, 3 wt%) of phthalocyanine containing zinc-based carborane units (ZnPc) are added into the Nylon 6.6 NFs. In accordance with the obtained results, the maximum open circuit voltage and power are measured as 228 V and 7.76 mW, respectively. These results correspond for the TENG system with 1% by weight ZnPc doped into the NFs. These results show that high-efficiency TENG systems can be obtained with nanofiber-based dielectric layers and can be used effectively in self-powered systems.