Research Project: Synthesis of single atom supported mesoporous black layered titania for H2 generation and CO2 fixation
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Contributors
Funders
ID
TB.00653
Authors
Doustkhah, Esmail
Researcher
Publications
Templated synthesis of exfoliated porous carbon with dominant graphitic nitrogen
(American Chemical Society, 2023) Tafazoli, Saeede; Balkan, Timuçin; Kaya, Sarp; Doustkhah, Esmail; Kotb, Ahmed; Hanaor, Dorian A. H.; Assadi, M. Hussein N.; KUTEM (Koç University Tüpraş Energy Center); Department of Chemistry; Graduate School of Sciences and Engineering; Yes; College of Sciences; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING; Research Center
We present here a new approach for the synthesis of nitrogen -doped porous graphitic carbon (g-NC) with a stoichiometry of C6.3H3.6N1.0O1.2, using layered silicate as a hard sacrificial template. Autogenous exfoliation is achieved due to the heterostacking of 2D silicate and nitrogen -doped carbon layers. Micro-and meso-porosity is induced by melamine and cetyltrimethylammonium (C16TMA). Our density functional calculations and X-ray photoelectron spectroscopy (XPS) observations confirm that the most dominant nitrogen configuration in g-CN is graphitic, while pyridinic and pyrrolic nitrogens are thermodynamically less favored. Our large-scale lattice dynamics calculations show that surface termination with H and OH groups at pores accounts for the observed H and O in the composition of the synthesized g-NC. We further evaluate the electrocatalytic and the supercapacitance activities of g-NC. Interestingly, this material exhibits a specific capacitance of ca. 202 F g-1 at 1 A g-1, retaining 90% of its initial capacitance after 10,000 cycles.
Single-atom sn-loaded exfoliated layered titanate revealing enhanced photocatalytic activity in hydrogen generation
(American Chemical Society (ACS), 2023) Kaya, Sarp; Üstünel, Tuğçe; Doustkhah, Esmail; Ide, Yusuke; Department of Chemistry; Graduate School of Sciences and Engineering; KUTEM (Koç University Tüpraş Energy Center); Yes; College of Sciences; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING; Research Center
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.
Ultrasonically-assisted synthesis of CeO(2) within WS(2) interlayers forming type II heterojunction for a VOC photocatalytic oxidation
(Elsevier, 2023) Doustkhah, Esmail; Hassandoost, R.; Yousef Tizhoosh, N.; Esmat, M.; Guselnikova, O.; Hussein N Assadi, M.; Khataee, A.; Department of Chemistry; KUTEM (Koç University Tüpraş Energy Center); No; College of Sciences; Research Center
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.
Stability trends in ono-metallic 3d layered double hydroxides
(Multidisciplinary Digital Publishing Institute (MDPI), 2022) Doustkhah, Esmail; Mohammadi, Saeedeh; Esmailpour, Ayoub; Assadi, Mohammad Hussein Naseef; Department of Chemistry; KUTEM (Koç University Tüpraş Energy Center); No; College of Sciences; Research Center
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.
Transforming Cl-containing waste plastics into carbon resource for steelmaking: theoretical insight
(American Chemical Society, 2023) Doustkhah, Esmail; Assadi, M. Hussein N.; KUTEM (Koç University Tüpraş Energy Center); Department of Chemistry; No; College of Sciences; Research Center
The accumulation of waste plastics poses a significant environmental challenge, leading to persistent pollution in terrestrial and aquatic ecosystems. A practical approach to address this issue involves the transformation of postconsumer waste plastics into industrially valuable products. This study focuses on an example of harnessing the carbon content in these polymers for carbon-demanding industrial processes, thereby reducing waste plastics from the environment and alleviating the demand for mined carbon resources. Employing quantum simulations, we examine the viability of polychloroprene as a carburizing agent in the steelmaking process. Our simulations reveal that polychloroprene exhibits excellent carbon diffusivity in molten iron, with a theoretical diffusion coefficient of 8.983 x 10(-5)cm(2) s(-1). This value competes favorably with that of metallurgical coke and surpasses the carbon diffusivity of other polymers, such as polycarbonate, polyurethane, and polysulfide. Additionally, our findings demonstrate that the chlorine content in polychloroprene does not permeate into molten iron but instead remains confined to the molten iron and slag interface.
