Researcher:
Doustkhah, Esmail

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Esmail

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Doustkhah

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Doustkhah, Esmail
Heragh, Doust Khah

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2022 - 20238

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Now showing 1 - 8 of 8
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    MOF-derived nanocrystalline ZnO with controlled orientation and photocatalytic activity
    (Elsevier Ltd, 2022) Esmat, Mohamed; Fukata, Naoki; Ide, Yusuke; Hanaor, Dorian A.H.; Assadi, M. Hussein N.; Department of Chemistry; Doustkhah, Esmail; Researcher; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); College of Sciences
    We show here that MOF-5, a sample Zn-based MOF, can uniquely transform into distinct zinc oxide nanostructures. Inspired by the interconversion synthesis of zeolites, we converted MOF-5 into nanocrystalline ZnO. We found the conversion of MOF-5 into ZnO to be tunable and straightforward simply by controlling the treatment temperature and choosing an appropriate structure-directing agent (SDA). Refined X-ray diffraction (XRD) patterns showed that a synthesis temperature of 180 °C (sample ZnO-180) was optimal for achieving high crystallinity. We examined ZnO-180 with high-resolution transmission electron microscopy (HRTEM), which confirmed that the samples were made of individual crystallites grown along the c-axis, or the (001) direction, thus exposing lower energy surfaces and corroborating the XRD pattern and the molecular dynamics calculations. Further investigations revealed that the obtained ZnO at 180 °C has a superior photocatalytic activity in degrading methylene blue to other ZnO nanostructures obtained at lower temperatures.
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    Structural conversion of Cu-Titanate into photoactive plasmonic Cu-Tio(2)for H(2)generation in visible light
    (American Chemical Society (ACS), 2022) Esmat, Mohamed; Abdelbar, Mostafa; Tahawy, Rafat; El-Hosainy, Hamza; Abdelhameed, Mohamed; Ide, Yusuke; Fukata, Naoki; Department of Chemistry; Doustkhah, Esmail; Researcher; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); College of Sciences; N/A
    Visible light-driven photocatalysts based on TiO2have significant potentialfor providing sustainable fuel for the future. Layered titanates, which have unique structures,are a focus of considerable research attention due to their ease of interconversion into newnanoarchitectures of TiO2that have high photocatalytic performance. We describe here thesynthesis of CuO nanostructures from the interconversion of copper titanate during thegeneration of TiO2nanosheets. We further examined thein situstructural transformation ofthe CuO-loaded TiO2nanosheets during photocatalytic hydrogen production fromammonia-borane (NH3middotBH3; AB) under visible light and studied the impact of thereaction media and of photoirradiation on the catalyst'sfinal structure by characterizing therecovered catalyst using X-ray diffraction (XRD), UV-vis, and transmission electronmicroscopy (TEM) analyses. The results show that the CuO nanoparticles are converted tometallic Cu nanoparticles, which photocatalyze the reaction through theirin situ-formedplasmonic features. The potential role of the introduced plasmonic Cu nanoparticles inpromoting charge separation and enhancing photocatalytic performance is also investigated.
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    Layered silicate stabilises diiron to mimic UV-shielding TiO2 nanoparticle
    (Elsevier, 2022) El-Hosainy, Hamza; Mine, Shinya; Toyao, Takashi; Shimizu, Ken-ichi; Tsunoji, Nao; Esmat, Mohamed; El-Kemary, Maged; Ide, Yusuke; Department of Chemistry; Doustkhah, Esmail; Researcher; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); College of Sciences; N/A
    Despite the ubiquity of aqua-Fe(III) complexes in biological enzymes and their useful properties and cost-effectiveness, artificially stabilizing these fleeting molecules for practical uses remains challenging. Herein, we demonstrate that a dimeric aqua-Fe(III) species can be stabilised using a flexible microporous layered silicate to produce a white UV-absorbing powder with significantly reduced undesirable photocatalytic activity. A mixture of this powder material and a natural oil is successfully employed to shield a UV-sensitive substrate; its shielding performance was comparable to that of a commercial-TiO(2)( )rutile coating. Comprehensive analyses and calculations reveal that a dihydroxo-bridged dimer, [(H2O)(OH)(2)O5FeIII(OH)(2)(FeOS)-O-III(H2O) (OH)(2)] (O-S: framework oxygen), fits the silicate pore and account for the stabilities and shielding properties of the material. Although TiO2 nanoparticles are widely used as UV absorbers in sunscreens and cosmetics, they pose health risks owing to their cytotoxicity. Thus, this material can serve as a safe, cost-effective alternative to TiO2 nanoparticles, either as a UV absorber or in other applications.
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    Pd thickness optimization on silicate sheets for improving catalytic activity
    (Wiley, 2023) Tsunoji, Nao; Assadi, M. Hussein N.; Ide, Yusuke; Department of Chemistry; Doustkhah, Esmail; Researcher; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); College of Sciences; N/A
    Maximizing surface-to-body ratio demands ever smaller metallic palladium (Pd) nanoparticles for catalytic applications. The quest for miniaturization is now reaching the single-atom limit. However, if the supported Pd is below a critical size, the Pd hybridization with the supporting material can detrimentally reduce the labile electrons that facilitate the catalytic reactions. Thus, the smallest attainable size, i.e., single-atom Pd, may not offer the best efficiency. Here, it is demonstrated that Pd with at least six atomic layers (or thickness of approximate to 1 nm) on the silicate sheets, synthesized via the partial exfoliation of a layered silicate, exhibits a metallic-like electronic property, yielding an excellent catalytic activity (e.g., turnover frequency) for dehydrogenating formic acid higher than both isotropic Pd nanoparticles and single-atom Pd.
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    Single-atom sn-loaded exfoliated layered titanate revealing enhanced photocatalytic activity in hydrogen generation
    (American Chemical Society (ACS), 2023) Ide, Yusuke; N/A; Department of Chemistry; Department of Chemistry; Üstünel, Tuğçe; Kaya, Sarp; Doustkhah, Esmail; Master Student; Faculty Member; Researcher; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; 116541; N/A
    Green H2 generation through layered materials plays a significant role among a wide variety of materials owing to their high theoretical surface area and distinctive features in (photo)catalysis. Layered titanates (LTs) are a class of these materials, but they suffer from large bandgaps and a layers' stacked form. We first address the successful exfoliation of bulk LT to exfoliated few-layer sheets via long-term dilute HCl treatment at room temperature without any organic exfoliating agents. Then, we demonstrate a substantial photocatalytic activity enhancement through the loading of Sn single atoms on exfoliated LTs (K0.8Ti1.73Li0.27O4). Comprehensive analysis, including time-resolved photoluminescence spectroscopy, revealed the modifica-tion of electronic and physical properties of the exfoliated layered titanate for better solar photocatalysis. Upon treating the exfoliated titanate in SnCl2 solution, a Sn single atom was successfully loaded on the exfoliated titanate, which was characterized by spectroscopic and microscopic techniques, including aberration-corrected transmission electron microscopy. The exfoliated titanate with an optimal Sn loading exhibited a good photocatalytic H2 evolution from water containing methanol and from ammonia borane (AB) dehydrogenation, which was not only enhanced from the pristine LT, but higher than conventional TiO2-based photocatalysts like Au-loaded P25.
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    PublicationOpen Access
    In situ formation of copper phosphate on hydroxyapatite for wastewater treatment
    (Multidisciplinary Digital Publishing Institute (MDPI), 2022) Rahmani, Fatemeh; Ghadi, Arezoo; Khaksar, Samad; Doustkhah, Esmail; PhD Student; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM)
    Here, we control the surface activity of hydroxyapatite (HAp) in wastewater treatment which undergoes peroxodisulfate (PDS) activation. Loading the catalytically active Cu species on HAp forms a copper phosphate in the outer layer of HAp. This modification turns a low active HAp into a high catalytically active catalyst in the dye degradation process. The optimal operational conditions were established to be [Cu-THAp](0) = 1 g/L, [RhB](0) = 20 mg/L, [PDS](0) = 7.5 mmol/L, and pH = 3. The experiments indicate that the simultaneous presence of Cu-THAp and PDS synergistically affect the degradation process. Additionally, chemical and structural characterizations proved the stability and effectiveness of Cu-THAp. Therefore, this work introduces a simple approach to water purification through green and sustainable HAp-based materials.
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    PublicationOpen Access
    Ultrasonically-assisted synthesis of CeO(2) within WS(2) interlayers forming type II heterojunction for a VOC photocatalytic oxidation
    (Elsevier, 2023) Hassandoost, R.; Yousef Tizhoosh, N.; Esmat, M.; Guselnikova, O.; Hussein N Assadi, M.; Khataee, A.; Department of Chemistry; Doustkhah, Esmail; Researcher; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); College of Sciences
    Here, we investigate the band structure, density of states, photocatalytic activity, and heterojunction mechanism of WS2 with CeO2 (CeO2@WS2) as a photoactive heterostructure. In this heterostructure, CeO2's growth within WS2 layers is achieved through ultrasonicating WS2 and intercalating CeO2's precursor within the WS2 interlayers, followed by hydrothermal treatment. Through a set of density functional calculations, we demonstrate that CeO2 and WS2 form an interface through a covalent bonding that can be highly stable. The electrochemical impedance spectroscopy (EIS) found that the CeO2@WS2 heterostructure exhibits a remarkably higher conductivity (22.23 mS cm(-2)) compared to either WS2 and CeO2, assignable to the interface in CeO2@WS2. Furthermore, in a physically mixed CeO2-WS2 where the interaction between particles is noncovalent, the resistance was significantly higher (0.67 mS cm(-2)), confirming that the heterostructure in the interface is covalently bonded. In addition, Mott-Schottky and the bandgap measurements through Tauc plots demonstrate that the heterojunction in CeO2 and WS2 is type II. Eventually, the CeO2@WS2 heterostructure indicated 446.7 mu mol g(-1) CO2 generation from photocatalytic oxidation of a volatile organic compound (VOC), formic acid, compared to WS2 and CeO2 alone.
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    PublicationOpen Access
    Stability trends in ono-metallic 3d layered double hydroxides
    (Multidisciplinary Digital Publishing Institute (MDPI), 2022) Mohammadi, Saeedeh; Esmailpour, Ayoub; Assadi, Mohammad Hussein Naseef; Department of Chemistry; Doustkhah, Esmail; Teaching Faculty; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); School of Sciences
    Layered double hydroxides (LDHs) constitute a unique group of 2D materials that can deliver exceptional catalytic, optical, and electronic performance. However, they usually suffer from low stability compared to their oxide counterparts. Using density functional calculations, we quantitatively demonstrate the crucial impact of the intercalants (i.e., water, lactate, and carbonate) on the stability of a series of common LDHs based on Mn, Fe, and Co. We found that intercalation with the singly charged lactate results in higher stability in all these LDH compounds, compared to neutral water and doubly charged carbonate. Furthermore, we show that the dispersion effect aids the stability of these LDH compounds. This investigation reveals that certain intercalants enhance LDH stability and alter the bandgap favourably.