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    Hexanediamine Monolayer Electrografted at Glassy Carbon Electrodes Enhances Oxygen Reduction Reaction in Aqueous Neutral Media
    (Electrochemical Soc Inc, 2020) Hamzah, Hairul Hisham; Kamal, Najahtul Najihah Ahmad; Meneghello, Marta; Shafiee, Saiful Arifin; Sonmez, Turgut; Taib, Mohamad Nurul Azmi Mohamad; Samsuri, Shazarizul Haziq Mohd
    This study presents for the first time the electrocatalytic behaviour of hexanediamine (HDA) monolayer electrografted at glassy carbon (GC) electrodes that enhanced oxygen reduction reaction (ORR) in aqueous neutral media. HDA modified GC electrodes gave a higher current density than platinum bare electrodes based on the cyclic voltammograms (CV), although a similar to 0.21 V vs. Ag/AgCl higher onset potential was observed at -0.1 mA cm(-2). Electrochemical impedance spectra (EIS) showed that the electrocatalytic reaction on HDA monolayer film towards dissolved oxygen molecules is controlled by diffusion and charge transfer processes. From the scan rate studies and the Laviron equation, it was found that the ORR on this modified electrode proceeded via a fast four-electrons transfer.
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    Hydrogen storage capabilities of ionothermally synthesized covalent triazine frameworks (CTFs)
    (Pergamon-Elsevier Science Ltd, 2023) Ergani, Songul Kaskun; Sonmez, Turgut; Uecker, Jan; Arpa, Beyza; Palkovits, Regina
    Covalent triazine frameworks (CTFs) represent an attractive new type of porous organic compounds demonstrating promising stability, nontoxicity, nitrogen functionalities and adjustable porosity. They have been greatly investigated in various applications; however, the hydrogen storage capacities of CTFs have been poorly described so far. Here, we present hydrogen storage capacities of a series of covalent triazine frameworks based on four different applied monomers (DCP, DCBP, mDCB and pDCB) synthesized via classical ionothermal route (ZnCl2, 400/600 degrees C). Among the synthesized CTFs, DCP shows the highest hydrogen storage capacity of 4.02 wt% at 20 bar, almost two times higher compared to the lowest value of 2.43 wt% for CTF DCBP. Furthermore, the CTF DCP outperforms with a H-2 uptake of 2.95 wt% at 1 bar pressure and 77 K state-of-the-art 2D porous organic polymers and shows very high uptake capability within the reported porous polymer materials. The high hydrogen storage capability of DCP is correlated to the high nitrogen (N) content of 20.4 wt%, high fraction of pyridinic N-sites (50.3%), the largest defect structure, highest crystallinity and microporosity among the synthesized CTFs. The specific surface area (SSA) and the total pore volume (TPV) seem to not have an influential impact on the H(2 )storage capacity as the CTF DCP exhibits the highest H-2 storage capacity with a SSA of 1737 m(2) g(-1) and a TPV of 0.9 cm(3) g(-1), the lowest values among the CTFs.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Metal free-covalent triazine frameworks as oxygen reduction reaction catalysts - structure-electrochemical activity relationship
    (Royal Soc Chemistry, 2021) Sonmez, Turgut; Belthle, Kendra Solveig; Iemhoff, Andree; Uecker, Jan; Artz, Jens; Bisswanger, Timo; Stampfer, Christoph
    Nitrogen-rich porous carbon polymers are highly promising oxygen reduction reaction (ORR) catalysts and possess great potential to replace Pt-based precious metals used in energy storage and conversion systems. In this study, covalent triazine frameworks (CTFs) were synthesized via an ionothermal route based on different monomers and synthesis temperatures (400-750 degrees C) and tested in alkaline media with a rotating disk electrode (RDE). The effect of the applied monomer and temperature on the surface functionalities of the frameworks and thus correlation to their ORR activities are deeply discussed. Micro/mesoporous, hierarchically ordered and highly conductive N-rich materials with up to 2407 m(2) g(-1) specific surface areas and 2.49 cm(3) g(-1) pore volumes were achievable. Owing to the high surface area (1742 m(2) g(-1)), pore volume (1.56 cm(3) g(-1)), highest conductivity, electrochemically active surface area and hierarchical mesoporous structure, CTF DCBP-750 facilitated 0.9 V onset potential (only 0.06 V larger than that of the benchmark 10 wt% Pt/C) with 5.1 mA cm(-2) limiting current density. In addition to the structural properties, graphitic nitrogen species, active sites responsible for binding and activating O-2, rather than pyridinic nitrogen appear to be more important for the overall ORR performance. Thus, the trade-off point is crucial to obtain optimal ORR activity with metal-free CTFs.
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    Recycling Chocolate Aluminum Wrapping Foil as to Create Electrochemical Metal Strip Electrodes
    (Mdpi, 2021) Hamzah, Hairul Hisham; Saleh, Nur Hidayah; Patel, Bhavik Anil; Mahat, Mohd Muzamir; Shafiee, Saiful Arifin; Sonmez, Turgut
    The development of low-cost electrode devices from conductive materials has recently attracted considerable attention as a sustainable means to replace the existing commercially available electrodes. In this study, two different electrode surfaces (surfaces 1 and 2, denoted as S1 and S2) were fabricated from chocolate wrapping aluminum foils. Energy dispersive X-Ray (EDX) and field emission scanning electron microscopy (FESEM) were used to investigate the elemental composition and surface morphology of the prepared electrodes. Meanwhile, cyclic voltammetry (CV), chronoamperometry, electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) were used to assess the electrical conductivities and the electrochemical activities of the prepared electrodes. It was found that the fabricated electrode strips, particularly the S1 electrode, showed good electrochemical responses and conductivity properties in phosphate buffer (PB) solutions. Interestingly, both of the electrodes can respond to the ruthenium hexamine (Ruhex) redox species. The fundamental results presented from this study indicate that this electrode material can be an inexpensive alternative for the electrode substrate. Overall, our findings indicate that electrodes made from chocolate wrapping materials have promise as electrochemical sensors and can be utilized in various applications.