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    Electrochemical Performance of a New Triazole Functionalized Ferrocene in Aqueous Redox Flow Batteries
    (Wiley, 2025) Eken, Taha Yasin; Gonzalez, Gabriel; Peljo, Pekka; Koz, Gamze
    A new 1,2,3-triazole functionalized ferrocene (1,2,3-TAFc) produced by Cu(I)-catalyzed click reaction was investigated as positive electrolyte for aqueous organic flow batteries (AOFBs). The molecule is highly soluble in 1 M hydrochloric acid and displays high electrochemical reversibility. 1,2,3-TAFc demonstrated good stability during cycling with a low capacity decay (0.011%/cyc, 3.0%/day) and high Coulombic efficiency (99.4%) over 280 cycles when tested in a flow battery at low concentration. This low capacity decay was attributed to the instability of ferrocene. These findings indicate that a stable and water-soluble catholyte for AOFBs can be obtained with structural modifications of 1,2,3-TAFc. A new type of ferrocene catholyte for AOFBs based on a 1,2,3-triazole moiety was introduced. 1,2,3-TAFc was prepared easily via click chemistry with a one-pot, two steps reaction sequence with 73% overall yield. The CV and flow battery experiments demonstrated the reversible and stable nature of the material. The cycling battery tests show a high stability of 1,2,3-TAFc in acidic electrolyte with low capacity decay (0.011%/cyc) and high Coulombic efficiency (99.4%).image
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    Graphene nanoplatelet-coated electrodes with cellulose binders for 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl-based aqueous proselyte
    (Taylor & Francis Inc, 2025) Eken, Taha Yasin; Kaykilarli, Cantekin; Tuna, Ali; Parmak, Ebru Devrim Sam; Uzunsoy, Deniz; Peljo, Pekka
    This study investigates the development of cellulose-bonded graphene nanoplatelet-coated electrodes for organic flow batteries (OFBs) utilizing 4-Hydroxy-2,2,6,6-Tetramethylpiperidine 1-oxyl (TEMPOL) as the active material. Graphite felt electrodes were coated via an optimized dip-coating process, varying the number of dips (1, 5 and 10). Cyclic voltammetry (CV) showed a 150% increase in oxidation peak current and a 250% increase in reduction peak current for the 10-dipped electrodes compared to pristine ones. Electrochemical impedance spectroscopy (EIS) revealed a 35% reduction in charge transfer resistance (Rp) for the 5-dipped electrodes, indicating enhanced ion transfer efficiency. Surface characterization analyses, including SEM, XRD and Raman spectroscopy, confirmed uniform graphene coatings and structural integrity, while contact angle measurements demonstrated a transition from hydrophobic (157 degrees) to hydrophilic (0 degrees) surfaces, improving wettability and electrolyte interaction. These findings establish cellulose as a sustainable, cost-effective binder, with potential scalability for large-scale energy storage applications.