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    A novel hazelnutt bagasse based activated carbon as sodium borohydride methanolysis and electrooxidation catalyst
    (Pergamon-Elsevier Science Ltd, 2023) Saka, Ceren; Yildiz, Derya; Kaya, Sefika; Caglar, Aykut; Elitok, Dilarasu; Yayli, Elif; Kaya, Mustafa
    In this study, activated carbon is produced from defatted hazelnut bagasse at different activation conditions. The catalytic activities of activated carbons are evaluated for NaBH4 methanolysis and electrooxidation. These materials are characterized by N2 adsorption -desorption, FTIR, SEM-EDS and XPS and results show that these materials are prepared successfully. N2 adsorption-desorption results reveal that activated carbon (FH3-500) has the highest BET surface area as 548 m2/g, total pore volume as 0.367 cm3/g and micropore volume as 0.205 cm3/g. On the orher hand, as a result of hydrogen production studies, FH3-500 activated carbon catalyst has the highest initial hydrogen production rate compared to other materials. At 50 & DEG;C, this metal-free activated carbon catalyst has a high initial hydrogen production rate of 13591.20 mL/min.gcat, which is higher than literature values. Sodium borohydride electrooxidation measurements reveal that FH2-500 also has the highest electrocatalytic activity and stability. Hazelnut pulp-based activated carbons are firstly used as a metal-free catalyst in the methanolysis and electrooxidation of sodium borohydride, and its catalytic activity is good as a metal-free catalyst. The results show that the hazelnut pulp-based activated carbon catalyst is promising as a metal-free catalyst for the methanolysis and electrooxidation of sodium borohydride.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Enhanced catalytic performance of Pd/PMAc-g-CNT composite for water splitting and supercapacitor applications
    (Springer Heidelberg, 2024) Hansu, Tulin Avci; Kaya, Sefika; Caglar, Aykut; Akdemir, Murat; Kivrak, Hilal Demir; Orak, Ceren; Horoz, Sabit
    In this study, we explore the multifaceted applications of poly(methyl acrylate) (PMAc)-based composites, specifically focusing on their use as an efficient electrocatalyst for water splitting and a high-capacity supercapacitor. After a synthesis step, a characterization study (SEM, TEM, XRD, and Raman spectroscopy) was performed, and based on TEM results, a consistent pattern of small, uniform, and narrowly distributed Pd NPs within the range of 5-10 nm was observed. Also, other analyses confirmed the successful synthesis of PMAc-based composites. Through meticulous experimentation, the electrocatalytic performance of Pd/PMAc-graphene-carbon nanotube (Pd/PMAc-g-CNT) composites was evaluated against that of traditional Pd/PMAc catalysts. Tafel slope analysis was conducted to assess the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) efficiencies, where Pd/PMAc-g-CNT composites demonstrated significantly lower Tafel slopes of 274.53 mV dec(-1) for OER and 389.91 mV dec(-1) for HER. This indicates a superior electrocatalytic activity, enhancing the water splitting process. Furthermore, the same composite showcased an impressive specific capacitance of 132.3 F g(-1) at a current density of 0.5 A/g, markedly surpassing the performance of the Pd/PMAc catalyst. This exceptional capacitance underlines its potential as a high-efficiency energy storage material. The novelty of this research lies in the synergistic integration of PMAc with graphene and carbon nanotubes to fabricate a dual-functional material. This composite not only excels in electrochemical catalysis for energy conversion but also demonstrates remarkable energy storage capabilities. The Pd/PMAc-g-CNT composite, therefore, emerges as a promising candidate for advancing supercapacitor technology and the electrocatalytic efficiency of water splitting, highlighting its dual utility in renewable energy systems.
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    Enhanced Photocatalytic Hydrogen Production on Cd-, Te-, Se-, and S-Doped Titanium Dioxide Catalysts
    (Springer, 2023) Kaya, Sefika; Saka, Ceren; Caglar, Aykut; Kaya, Mustafa; Kivrak, Hilal
    Herein, cadmium (Cd)-, tellurium (Te)-, selenium (Se)-, and sulfur (S)-doped titanium dioxide (TiO2) support material catalysts are prepared via incipient wetness impregnation. Hydrogen generation performances of the prepared catalysts from sodium borohydride (NaBH4) by methanolysis are investigated. Experimental studies are carried out under ultraviolet (UV) illumination and in the dark. The highest initial hydrogen generation rate is reached on 0.1% Cd/TiO2 catalyst under UV illumination. The optimum catalyst, sodium borohydride, and methanol amounts and temperature parameters affecting the initial hydrogen generation rate are investigated and obtained as 0.025 g, 0.150 g, 2 mL, and 60 degrees C, respectively. The initial hydrogen generation rate of 0.1% Cd/TiO2 catalyst is 16130.64 mL/min.gcat in optimum conditions. The activation energy of the reaction with the 0.1% Cd/TiO2 catalyst is calculated by carrying out kinetic studies. The activation energy is 22.48 kJ/mol. X-ray diffraction (XRD), electron microscopy with energy-dispersive x-ray spectroscopy (SEM-EDX), inductively coupled plasma mass spectrometry (ICP-MS), x-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) analytical techniques are performed to characterize the catalysts. The results show that TiO2 catalysts doped with Cd, Te, Se, and S, which are cheaper than noble metals, are promising for the production of hydrogen from NaBH4 by methanolysis under UV illumination.
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    Exploring the Triple Applications of Ag/PMAc-g-CNT Nanocomposites in Enhancing HER, OER and Supercapacitor Performance
    (Springer, 2024) Kaya, Sefika; Caglar, Aykut; Akdemir, Murat; Kivrak, Hilal Demir; Horoz, Sabit; Kaya, Mustafa
    The research aims to investigate the potential of using Ag/PMAc-g-CNT as a high-efficient catalyst for overall water splitting and supercapacitor applications. The results of Tafel slope measurements for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) showed that the Ag/PMAc-g-CNT catalyst had a lower Tafel slope of 22.62 mV dec-1 and 62.74 mV dec-1, respectively, compared to the other electrocatalysts. Additionally, the capacitance value of the Ag/PMAc-g-CNT catalyst was found to be 41.87 F at 0.5 A/g current density which is much higher than that of the Ag/PMAc catalyst. These results demonstrate that the Ag/PMAc-g-CNT catalyst has superior properties in terms of electrochemical activity, stability and energy storage capacity, making it a promising material for both water splitting and supercapacitor applications.
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    High-efficiency catalyst for water splitting and supercapacitor applications: the promising role of Ni/PMAc-g-CNT
    (Springer Heidelberg, 2023) Caglar, Aykut; Kaya, Sefika; Avci Hansu, Tuelin; Akdemir, Murat; Demir Kivrak, Hilal; Horoz, Sabit; Kaya, Mustafa
    In this study, we investigated the use of electrocatalysts, PMAc, PMAc-g-CNT, Ni/PMAc, and Ni/PMAc-g-CNT for water splitting and supercapacitor applications. Our results showed that the Ni/PMAc-g-CNT catalyst exhibited superior properties in terms of electrochemical activity, stability, and energy storage capacity. The Tafel slope for OER was found to be 471.25 mV dec(-1), which was lower than other catalysts studied. The capacitance value of the Ni/PMAc-g-CNT catalyst was 35.23 F/g at 0.5 A/g current density, which was higher than the Ni/PMAc catalyst. These findings provide a novel and detailed insight into the performance of these catalysts and suggest that the Ni/PMAc-g-CNT catalyst is a promising material for both water splitting and supercapacitor applications.