Browsing by Author "Cogenli, Mehmet Selim"

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Effective Carbon Nanotube Supported Metal (M=au, Ag, Co, Mn, Ni, V, Zn) Core Pd Shell Bimetallic Anode Catalysts for Formic Acid Fuel Cells
(Pergamon-elsevier Science Ltd, 2020) Caglar, Aykut; Cogenli, Mehmet Selim; Yurtcan, Aye Bayrakceken; Kivrak, Hilal
At present, CNT supported Pd and core-shell Pd-based catalysts are synthesized by employing the NaBH4 reduction method to investigate on formic acid electrooxidation (FAEO) activity. These catalysts are characterized by XRD, TEM, HRTEM, and XPS. The XRD results display that the electronic state of catalysts changed by second metal addition to Pd. TEM results reveal that Au and Pd are homogeneously distributed. XPS results of AucorePdshell/CNT catalyst show that Au and Pd atoms used in the preparation of the catalyst are obtained mainly in elemental state. The FAEO activity, stability, and resistance of these catalysts are investigated by employing cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). The CV results show that AucorePdshell/CNT catalyst having 16.42 mAcm(-2) specific activity and 4978.23 mA mg(-1) Pd mass activity is better than other catalysts. In addition, the AucorePdshell/CNT (21 m(2)/g) catalyst has better electrochemical active surface area (ECSA) value as 5.25 times compared with Pd/CNT catalyst. Direct formic acid fuel cell (DFAFC) performances are performed at different temperatures for AucorePdshell/CNT and NicorePdshell/CNT catalysts. The specific activity of AucorePdshen/CNT catalyst is 2.5 times higher than the value for NicorePdshell/CNT catalyst. AucorePdshell catalyst is a promising catalyst for DFAFCs. (C) 2019 Elsevier Ltd. All rights reserved.
Remarkable Activity of a Znpdpt Anode Catalyst: Synthesis, Characterization, and Formic Acid Fuel Cell Performance
(Pergamon-elsevier Science Ltd, 2021) Caglar, Aykut; Cogenli, Mehmet Selim; Yurtcan, Ayse Bayrakceken; Alal, Orhan; Kivrak, Hilal
Herein, multi-walled carbon nanotube (MWCNT) supported Zn-Pd and Zn-Pd-Pt catalysts have been prepared utilizing a sequential sodium borohydride (SBH) reduction method. The resulting Zn/MWCNT, Zn-Pd/MWCNT, and Zn-Pd-Pt/MWCNT catalysts were characterized using advanced surface analytical techniques such as X-ray diffraction (XRD), high contrast transmission electron microscopy (C-TEM), and X-ray photoelectron spectroscopy (XPS). The characterization results indicate that the Zn/MWCNT, Zn-Pd/MWCNT, and Zn-Pd-Pt/MWCNT catalysts were successfully prepared. It was observed that Pd and Pt incorporation into Zn alters the electronic structure of Zn. Cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) were used to examine the electrochemical activity of the catalysts toward the electrooxidation of formic acid (FA). The results reveal that ZnPdPt/MWCNT has a specific activity of 12.6 mA/cm(2) and an electrochemical active surface area (ECSA) of 41.1 m(2)/g. This catalyst shows high activity, stability, and resistance when compared to Pd/MWCNT and ZnPd/MWCNT. Direct FA fuel cell (DFAFC) measurements were performed at 18-60 degrees C for the ZnPd/MWCNT and ZnPdPt/MWCNT catalysts. The specific activity of ZnPdPt/MWCNT was 1.45 times greater than that measured for ZnPd/MWCNT. ZnPdPt/MWCNT is a promising catalyst according to our CV, CA, EIS, and DFAFC measurements.
Synthesis and Characterization of Co, Zn, Mn, V Modified Pd Formic Acid Fuel Cell Anode Catalysts
(Elsevier Science Sa, 2019) Caglar, Aykut; Ulas, Berdan; Cogenli, Mehmet Selim; Yurtcan, Aye Bayrakceken; Kivrak, Hilal
In this study, carbon nanotube (CNT) supported Pd50Co50, Pd50V50, Pd50Mn50, and Pd50Zn50 bimetallic catalysts are prepared by using sodium borohydride (NaBH4) reduction method to investigate their formic acid electrooxidation (FAEO) activities. These catalysts are characterized by using X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES), and X-ray Photoelectron Spectroscopy (XPS). The XRD results show that the electronic state of catalysts varied by second metal addition to Pd. TEM results reveal that Pd and Co are homogeneously distributed. The result of Pd43Co57/CNT obtained by ICP-OES analysis of Pd50Co50/CNT catalyst shows that the synthesis was successfully synthesized. XPS results of Pd50Co50/CNT and Pd50Zn50/CNT catalysts showed that Pd, Zn, and Co atoms used in the preparation of the catalysts were obtained mainly in their elemental state. In addition, FAEO activity and stability of these catalysts are examined by using cyclic voltammetry (CV) and chronoamperometry (CA). Pd50Co50/CNT indicated the highest specific and mass activities with 6.89 mA/cm(2) and 649.69 mA/mg Pd, respectively. Direct formic acid fuel cell (DFAFC) performances are performed in different temperatures for Pd50Co50/CNT catalyst. The specific current for DFAFC performance of this catalyst was evaluated as 5.71, 6.87, and 2.43 mA/cm(2) at 18 degrees C, 30 degrees C, and 60 degrees C cell temperature at 0.5 V, respectively. (C) 2019 Elsevier B.V. All rights reserved.