Use Of Thiophene As Pt Catalyst support Material For Elektrochemical Oxidation Of Methanol

Abstract

In this study, modified electrode systems were prepared to be used directly in methanol fuel cells. To examine the electrochemical behavior of the modified electrode systems for methanol oxidation, cyclic voltammetry (CV), chronoamperometry (CHR), and electrochemical impedance spectroscopy (EIS) methods were used. Pencil tip graphite (KUG) used as the working electrode. Optimizations of voltage range, scanning speed, number of cycles and acid concentration in anhydrous medium, were made for electropolymerization of thiophene (Th) on the surface of the KUG electrode by CV method. Then, platinum (Pt) as a catalyst, was doped on the polymer film at 4 different concentrations (3, 3.25, 3.50 and 3.75mM). The electrochemical behavior of the modified electrode systems for methanol oxidation was investigated and interpreted. In addition, SEM-EDS analyzes of the modified electrode systems which used in the study were performed to be informed about the morphological structures of the polymer films and the amount of Pt doped to the films. Based on the results; when the conductive polymer film and Pt are used as catalyst separately for methanol oxidation, the responses are almost similar. However, when conductive polymer used as a support material for Pt as catalyst, it exposes very high methanol oxidation performance. The electrochemical active surface area (ECSA) and specific capacitance (Cs) values for the modified electrodes were calculated using the data obtained from the results of CV and EIS methods. The highest calculated ECSA and Cs values are 1.17 m2/gr and 0.21 Fg-1, respectively, and belonging to the KUG/3.50mMPt@PTh electrode.

Keywords

• Methanol oxidation
• Pt
• Polythiophene
• Conductive polymer
• Electrochemical oxidation
• Fuel cell.

Metanolün Elektrokimyasal Yükseltgenmesi İçin Pt katalizör Destek Malzemesi Olarak Tiyofen Kullanımı

Abstract

Bu çalışma da, doğrudan metanol yakıt hücrelerinde kullanılmak üzere modifiye elektrot sistemleri hazırlanmıştır. Hazırlanan elektrot sistemlerinin metanol oksidasyonuna ait elektrokimyasal davranışlarını incelemek için dönüşümlü voltametri (CV), kronoamperometri (CHR), ve elektrokimyasal empedans spektroskopisi (EIS) yöntemleri kullanılmıştır. Çalışma elektrotu olarak kalem ucu grafit (KUG) kullanılmıştır. KUG elektrotun yüzeyinde tiyofenin (Th) susuz ortamda CV yöntemi ile elektropolimerizasyonu için gerilim aralığı, tarama hızı, döngü sayısı ve asit derişimi optimizasyonları yapılmıştır. Daha sonra katalizör olarak polimer filmin üzerine platin (Pt) 4 faklı derişimde (3, 3,25, 3,50 ve 3,75mM) katkılanmıştır. Hazırlanan modifiye elektrot sistemlerinin metanol oksidasyonuna ait elektrokimyasal davranışları araştırılıp yorumlanmıştır. Bununla birlikte çalışmada kullanılan modifiye elektrot sistemlerinin SEM-EDS analizleri yapılarak polimer filmlerin morfolojik yapıları hakkında ve filmlere katkılanan Pt miktarları ile ilgili bilgi edinilmiştir. İletken polimer filmi ve Pt metanol oksidasyonu için ayrı ayrı katalizör olarak kullanıldıklarında alınan cevaplar hemen hemen benzerdir. Ancak iletken polimer Pt için destek malzeme olarak kullanıldığında, oldukça yüksek metanol oksidasyon performansı göstermektedir. CV ve EIS yöntemleri kullanılarak yapılan analizler sonucu elde edilen verilerden yararlanılarak modifiye elektrotların elektrokimyasal aktif yüzey alan (ECSA) ve spesifik kapasitans (Cs) değerleri hesaplanmıştır. Hesaplanan en yüksek ECSA ve Cs değerleri sırasıyla 1,17 m2/gr ve 0,21 Fg-1olup KUG/3,50mMPt@PTh elektroduna aittirler.

Keywords

• Metanol oksidasyonu
• Pt
• Politiyofen
• İletken polimer
• Elektrokimyasal oksidasyon
• Yakıt hücresi

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