• Title/Summary/Keyword: fluorine potential

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Synthesis and Investigation of LiVPO4O1-xFxvia Control of the Fluorine Content for Cathode of Lithium-ion Batteries (플루오린 함량 제어를 통한 LiVPO4O1-xFx 합성 및 리튬 이차전지 양극소재 전기화학 특성 분석)

  • Minkyung Kim;Dong-hee Lee;Changyu Yeo;Sooyeon Choi;Chiwon Choi;Hyunmin Yoon
    • Journal of Powder Materials
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    • v.30 no.6
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    • pp.516-520
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    • 2023
  • Highly safe lithium-ion batteries (LIBs) are required for large-scale applications such as electrical vehicles and energy storage systems. A highly stable cathode is essential for the development of safe LIBs. LiFePO4 is one of the most stable cathodes because of its stable structure and strong bonding between P and O. However, it has a lower energy density than lithium transition metal oxides. To investigate the high energy density of phosphate materials, vanadium phosphates were investigated. Vanadium enables multiple redox reactions as well as high redox potentials. LiVPO4O has two redox reactions (V5+/V4+/V3+) but low electrochemical activity. In this study, LiVPO4O is doped with fluorine to improve its electrochemical activity and increase its operational redox potential. With increasing fluorine content in LiVPO4O1-xFx, the local vanadium structure changed as the vanadium oxidation state changed. In addition, the operating potential increased with increasing fluorine content. Thus, it was confirmed that fluorine doping leads to a strong inductive effect and high operating voltage, which helps improve the energy density of the cathode materials.

A Study on the Reference Electrode for Al Concentration Sensor in Zinc Galvanizing Melt (용융아연 도금욕중 Al농도 센서의 기준전극에 대한 연구)

  • Jung, W.G.;Jung, S.H.
    • Korean Journal of Materials Research
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    • v.16 no.2
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    • pp.129-136
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    • 2006
  • In order to get basic information on the reference electrode material for the long life Al concentration sensor in zinc galvanizing melt, the workability and stability of fluorine potential cell with $CaF_2$ single crystal electrolyte were examined carefully at constant temperature for six kinds of reference materials (Zn, Sn, Cd, Bi, Pb, Al-Sn alloy + fluorides). Good workability and stability of the sensor were found in sensor with $Bi+BiF_3$ reference electrode. The Al sensor with $Bi+BiF_3$ reference electrode was assembled and was tested in Zn-Al melt with different Al concentration. The EMF was changed rapidly with the change of Al concentration and was stabilized in a short time. Thus the response of EMF was satisfactory for $CaF_2$ sensor. The correlationship between EMF from the sensor and logarithm of Al concentration has been derived from the least square regression method. E/mV=57.515log[wt% Al]+1883.3 R=0.9717 ($0.013{\leq}[wt% Al]{\leq}0.984$) The EMF from Al sensor was increased linearly against logarithm of [wt% Al]. The fluorine potential of Zn-Al melt was also calculated to be in the range of $10^{-60}{\sim}10^{-61}$ Pa for the present experiemental condition.

Organometallic fluorine-18 bonds in 18F-radiochemistry

  • Joong-Hyun Chun;Minju Lee;Sungwon Jun;Jeongmin Son
    • Journal of Radiopharmaceuticals and Molecular Probes
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    • v.7 no.1
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    • pp.22-32
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    • 2021
  • Fluorine-18 is by far the most widely exploited radionuclide in PET (positron emission tomography) radiochemistry. The physical half-life of fluorine-18 allows for chemical manipulation within a restricted timeframe, and cyclotron-produced fluoride ion has been widely applied in aliphatic and aromatic nucleophilic radiofluorinations to produce a variety of established radiotracers. Radiotracers have become more structurally complicated to address diverse targets in physiobiological systems. There is therefore an unmet need to complement traditional C-18F bond-forming radiofluorination with new and efficient radiolabeling techniques to tackle the myriad of possible chemical environments. This review discusses recent advances in organometallic fluorine-18 bond creation in 18F-radiochemistry. Although not widely employed, new radiolabeling strategies for constructing boron-18F, silicon-18F, aluminum-18F, and other metal-18F bonds are described in view of their potential use in the development of novel radiopharmaceuticals.

Stabilization of fluorine in soil using calcium hydroxide and its potential human health risk

  • Jeong, Seulki;Kim, Doyoung;Yoon, Hye-On
    • Environmental Engineering Research
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    • v.24 no.4
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    • pp.654-661
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    • 2019
  • This study assessed the stabilization of fluorine (F)-contaminated soil using calcium hydroxide (Ca(OH)2) and the consequent changes in human health risk. The bioavailable F decreased to 3.5%, (i.e., 57.9 ± 1.27 mg/kg in 6% Ca(OH)2-treated soil sample) from 43.0%, (i.e., 711 ± 23.4 mg/kg in control soil sample). This resulted from the conversion of water-soluble F to stable calcium fluoride, which was confirmed by XRD spectrometry. Soil ingestion, inhalation of fugitive dust from soil, and water ingestion were selected as exposure pathways for human health risk assessment. Non-carcinogenic risks of F in soils reduced to less than 1.0 after stabilization, ranging from 4.2 to 0.34 for child and from 3.0 to 0.25 for adult. Contaminated water ingestion owing to the leaching of F from soil to groundwater was considered as a major exposure pathway. The risks through soil ingestion and inhalation of fugitive dust from soil were insignificant both before and after stabilization, although F concentration exceeded the Korean soil regulatory level before stabilization. Our data suggested that substantial risk to human health owing to various potential exposure pathways could be addressed by managing F present in soil.

Impact of Cyano and Fluorine Group Functionalization on the Optoelectronic and Photovoltaic Properties of Donor-Acceptor-π-Acceptor Benzothiadiazole Derived Small Molecules: A DFT and TD-DFT Study

  • Prabhat Gautam;Anurag Gautam;Neeraj Kumar
    • Korean Journal of Materials Research
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    • v.33 no.6
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    • pp.236-241
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    • 2023
  • Solar cells based on p-conjugated donor-acceptor (D-A) organic molecular systems are a promising alternative to conventional electrical energy generation. D-A molecular systems, which have a triphenylamine (TPA) moiety linked with a benzothiadiazole (BTD) moiety, open the potential development of new small molecule donors for bulk heterojunction (BHJ) solar cells. Here, a series of donor-acceptor-π-acceptor (D-A-π-A) small molecule donors (SMD) derived from triphenylamine (TPA) donor and benzothiadiazole (BTD) acceptor building blocks, were designed for BHJ organic solar cells. The small molecule donors SMD1-4 were studied using density functional theory (DFT) and time dependent-DFT (TDDFT) methods, to understand the effect of cyano and fluorine group functionalization on their properties. The effect of structure alteration by cyano and fluorine group functionalization on the optoelectronic properties, the calculated highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) and the HOMO-LUMO gaps were theoretically explored. The Voc (open-circuit photovoltage) and fill factor (FF) for SMD1-4 were obtained with a PC71BM acceptor, which showed that these organic small molecules are potential small molecule donors for organic bulk heterojunction solar cells.

Synthesis, Characterization and Catalytic Evaluation of Zinc Fluorides for Biodiesel Production

  • Indrayanah, Sus;Marsih, I Nyoman;Murwani, Irmina Kris
    • Journal of the Korean Chemical Society
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    • v.62 no.1
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    • pp.7-13
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    • 2018
  • The potential of zinc fluorides with different molar ratios of Zn/F was applied as a solid catalyst in the simultaneous reaction of transesterification and esterification of crude palm oil (CPO) for biodiesel production. These materials were prepared by the fluorolytic sol-gel technique with different fluorine contents. The resulting samples were investigated using elemental analysis, XRD, FT-IR, TG/DTG, $N_2$ physisorption measurements and SEM. The results exhibited that the presence of fluorine strongly affected the catalytic activity in the biodiesel production. The catalysts with smaller fluorine contents (${\leq}1$) showed the best performance in all of the observed samples, yields from 92.94 to 89.95, 87.38 and 85.21% with increasing fluorine contents, respectively. The yield toward the formation of biodiesel depended on the phase and particle sizes of catalysts, but it was not influenced by surface area, pore size, and volume of the samples. The recovered catalyst showed a gradual decrease in activity over three cycles of same reactions.

A Novel Aromatic Fluorine-18 Labeling Method Using Iodonium Salts Precursor (이오도늄 솔트 전구체를 이용한 새로운 방향족 화합물 플루오린-18 표지 기술)

  • Moon, Byung-Seok;Lee, Byung-Chul;Kim, Sang-Eun
    • Nuclear Medicine and Molecular Imaging
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    • v.43 no.1
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    • pp.1-9
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    • 2009
  • As many new drug substances contained various aromatic rings and fluorine attached to an electron rich aromatic ring or on the meta-position, a strategy towards improvement in aromatic fluorination of these compounds is highly desirable. The introduction of fluorine-18 onto aromatic rings showed in the limited condition containing electron withdrawing group (EWG) on the para- or ortho-position to get reasonable radiochemical yield so far. No-carrier added (NCA) [$^{18}F$]fluoroarene syntheses by iodonium salts recently reported that has the potential to greatly increase the yield in systems or positions that normally not reactive enough to give sufficient yields in simple model reaction. This review describes the methodological approach towards effective aromatic fluorination by diaryliodonium salts and future prospects in an application of novel PET radiotracer.

Application of Rare Earth Compounds for the Treatment of Phosphate and Fluoride in Wastewater (인산염 및 불소폐수 처리제로서의 희토류 화합물 적용에 관한 연구)

  • Kim, Jin-Wha;Shin, Sung-Hye;Song, Hye-Won;Kim, Dong-Su;Woo, Sang-Mo;Kwon, Young-Shik
    • Journal of Korean Society of Environmental Engineers
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    • v.22 no.6
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    • pp.1127-1137
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    • 2000
  • Applications of lanthanum ion and crude rare earth chloride to the phosphate wastewater and fluorine wastewater, respectively, as treatment agents were studied. For the investigation of phosphate removal characteristics according to the amount of lanthanum ion, initial phosphate content was decreased by about 50% when molar ratio of [$La^{3+}$]:[$PO_4{^{3-}}-P$] was 0.25 and nearly all of phosphate was removed when the molar ratio of [$La^{3+}$]:[$PO_4{^{3-}}-P$] to be doubled. The removal of phosphate by $La^{3+}$ appeared to reach equilibrium state rapidly, and it was exothermic reaction since the removed amount of phosphate was diminished somewhat when the reaction temperature was increased. The zeta potential of combined particulate compound of lanthanum ion and phosphate was located for its isoelectric point at pH 5.5 and the turbidity of treated wastewater was found to vary according to the pH in a similar manner as the absolute value of zeta potential of the combined particulate compound did. For the treatment of fluorine wastewater by crude rare earth chloride, the remaining fluorine content after treatment decreased as the dosage of crude rare earth chloride increased. Whereas, the turbidity of treated wastewater and the amount of sludge generated were shown to increase as more crude rare earth chloride was added. The remaining fluorine content and the turbidity of treated wastewater were decreased and the amount of sludge generated was observed to increase according the increase of coagulant dosage under the condition of constant input of crude rare earth chloride.

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Electrodeposition of Gold on Fluorine-Doped Tin Oxide: Characterization and Application for Catalytic Oxidation of Nitrite

  • Rahman, Md. Mahbubur;Li, Xiao-Bo;Lopa, Nasrin Siraj;Lee, Jae-Joon
    • Bulletin of the Korean Chemical Society
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    • v.35 no.7
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    • pp.2072-2076
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    • 2014
  • Sub-micrometer size gold particles were electrodeposited on a transparent fluorine-doped tin oxide (FTO) from acetonitrile solution containing $AuCl_4{^-}$ and tetramethylammonium tetraflouroborate (TMATFB) for detecting $NO_2{^-}$. A series of two-electron ($2e^-$) and one-electron ($1e^-$) reductions of the $AuCl_4{^-}-AuCl_2{^-}-Au$ redox systems were observed at FTO and a highly stable and homogeneous distribution of Au on FTO (Au/FTO) was obtained by stepping the potential from 0 to -0.55 V (vs. Ag/$Ag^+$). The Au/FTO electrode exhibited sufficiently high catalytic activity toward the oxidation of $NO_2{^-}$ with a detection limit (S/N = 3) and sensitivity of 2.95 ${\mu}M$ and 223.4 ${\mu}A{\cdot}cm^{-2}{\cdot}mM^{-1}$, respectively, under optimal conditions. It exhibited an interference-free signal for $NO_2{^-}$ detection with excellent recoveries from real samples.

Electrosynthesis of n-PFOSF with Potential Operation (정전위법에 의한 n-PFOSF 합성)

  • Lee, Jongil;Tae, Beomseok
    • Applied Chemistry for Engineering
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    • v.7 no.3
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    • pp.473-480
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    • 1996
  • Synthesis of n-perfluorooctanesulfonyl fluoride(n-PFOSF), which is valuable precursor perfluoro-chemicals, was studied by electrochemical fluorination(ECF). Of prime concern was to investigate the cyclic voltamograms of Ni electrode in anhydrous hydrogen fluoride(AHF) with and without the reactants and to measure fluorine evolution potential. In a batch cell, chronoampherometric electrolysis and various chemical analysis such as GC, GC/MS and IR were used to understand the amphere change of electrode and the reaction paths. Fluorine equilibrium potential was found to be about 2.8V(vs. $Cu/CuF_2$) from the cyclic voltammograms and decay curves of anode potential in AHF. In batch processes, the ECF proceeded in two distinguished steps. The first step proceeded electrochemically and the second one chemically. Under 7V(vs. $Cu/CuF_2$), amount of crude products was proportional to the applied anode potential. Above 7V(vs. $Cu/CuF_2$), it had a hundred percentage with weight ratio of reactants and productivity of PFOSF was almost constant.

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