Chemistry / Kimya
Permanent URI for this collectionhttps://hdl.handle.net/11147/4072
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Article Citation - WoS: 41Citation - Scopus: 44Ultralong-Life Quinone-Based Porous Organic Polymer Cathode for High-Performance Aqueous Zinc-Ion Batteries(American Chemical Society, 2023) Büyükçakır, Onur; Yüksel, Recep; Begar, Ferit; Erdoğmuş, Mustafa; Arsakay, Madi; Lee, Sun Hwa; Kim, Sang OukWe synthesized and studied a redox-active quinone-basedporousorganic polymer (rPOP) and found ultralong cycle life: it is a promisingorganic cathode for aqueous zinc-ion batteries (ZIBs). It has highphysicochemical stability and enhanced intrinsic conductivity fromits fused-aromatic conjugated skeleton. rPOP's high porosityallows for efficient Zn2+ infiltration through the poresduring charging-discharging cycles and contributes to the efficientutilization of redox-active quinone units. It delivers a specificcapacity of 120 mAh g(-1) at a current density of0.1 A g(-1) with a flat and long discharge plateau,which is critically important to provide a stable voltage output.It provides ultralong cycle life at a current density of 1.0 A g(-1) for 1000 and at 2.0 A g(-1) for 30 000cycles, with initial capacity retention of 95 and 66%, respectively.The co-insertion (Zn2+ and H+) charge storagemechanism was investigated using various electrochemical measurementsand ex/in situ structural characterization techniques, and is explainedherein. These findings contribute to a better understanding of thestructure-property relationship for rPOP and open a new avenuefor new organic cathode materials for high-performance next-generationaqueous batteries.Article Citation - WoS: 3Citation - Scopus: 3Continuous Production of Hyperbranched Polyhydrocarbons by Electrochemical Polymerization of Chlorinated Methanes(Royal Society of Chemistry, 2022) Seo, Jae Hong; Nam, Hyun Ju; Rajendiran, Rajmohan; Seong, Won Kyung; Jiang, Yi; Kim, Min Hyeok; Büyükçakır, OnurA continuous production of polyhydrocarbon (PHC) by electrochemical polymerization of chlorinated hydrocarbons is presented. Monomer loading and product transfer were controlled by changing flow direction in a home-built continuous flow system that facilitates preparation, work-up, and scale-up of electrochemical polymerization. The polymerization can be tuned by adjusting reaction time, cell configuration, molar ratio of input chemicals, and the solvent type. CH2Cl2, CHCl3, and CCl4 were used to synthesize PHC. The reduction of the monomers at the cathode was studied by cyclic voltammetry and chronoamperometry. We investigated the structure and composition of PHCs from FT-IR and NMR spectra along with elemental analysis. Sufficient amounts of product are generated by continuous production and characterization of the product PHCs by a wide variety of methods is possible. Particularly, structural analysis by various C-13 NMR techniques suggests a new pathway for the synthesis of hyperbranched PHCs by electrochemical polymerization.Article Citation - WoS: 5Citation - Scopus: 5Structural Analysis of Hyperbranched Polyhydrocarbon Synthesized by Electrochemical Polymerization(Royal Society of Chemistry, 2022) Jiang, Yi; Kim, Minhyeok; Nam, Hyunju; Kwak, Sang Kyu; Ruoff, Rodney S.; Lee, Sun Hwa; Seo, Jae Hong; Shin, Eunhye; Joo, Se Hun; Büyükçakır, OnurWe describe a structural analysis method for a hyperbranched polyhydrocarbon (PHC) produced by electrochemical polymerization. Nuclear magnetic resonance (NMR) techniques including 1H-NMR, quantitative 13C-NMR, DEPT 13C-NMR, and 1H-13C HSQC 2D NMR along with elemental analysis and FTIR were used to experimentally assess the likely structure of this complex polymer with random branching. The polymer structure was modeled based on the NMR results. Room temperature density, refractive index, melting temperature, and IR spectrum were good matches to the values, and spectrum, calculated using the simulated structure. Calculated Hildebrand solubility parameters for the simulated structure rationalize the room temperature solubility measured in a range of solvents. The experimental and modeling methods are likely to be applicable to any type of highly branched random branching polymer. To the best of our knowledge, this is the first comprehensive elucidation of the structure of an unknown and randomly hyperbranched polymer by combining experimental results and theoretical simulation, and the methods described should find broad use in the future.Article Citation - WoS: 111Citation - Scopus: 97A General Approach To Composites Containing Nonmetallic Fillers and Liquid Gallium(American Association for the Advancement of Science, 2021) Wang, Chunhui; Gong, Yan; Cunning, Benjamin, V; Lee, Seunghwan; Le, Quan; Joshi, Shalik R.; Büyükçakır, OnurWe report a versatile method to make liquid metal composites by vigorously mixing gallium (Ga) with non-metallic particles of graphene oxide (G-O), graphite, diamond, and silicon carbide that display either paste or putty-like behavior depending on the volume fraction. Unlike Ga, the putty-like mixtures can be kneaded and rolled on any surface without leaving residue. By changing temperature, these materials can be stiffened, softened, and, for the G-O-containing composite, even made porous. The gallium putty (GalP) containing reduced G-O (rG-O) has excellent electromagnetic interference shielding effectiveness. GalP with diamond filler has excellent thermal conductivity and heat transfer superior to a commercial liquid metal-based thermal paste. Composites can also be formed from eutectic alloys of Ga including Ga-In (EGaIn), Ga-Sn (EGaSn), and Ga-In-Sn (EGaInSn or Galinstan). The versatility of our approach allows a variety of fillers to be incorporated in liquid metals, potentially allowing filler-specific fit for purpose materials.