Borik asit ve boron fosfat destekli, sülfonlanmış polistiren/polivinil alkol kompozit membran sentezi ve karakterizasyonu

Polimer elektrolit yakıt hücreleri (PEMFC), işletimlerinin kolay olması, yüksek enerji yoğunlukları, verimlerinin içten yanmalı motorlara göre çok yüksek olması ve zararlı emisyonlarının olmaması nedeniyle en fazla umut vaat eden güç kaynağı adayıdır. PEMFC’nin kalbini proton değiştirici membran oluşturmaktadır Günümüzde elektrolit olarak kullanımı en yaygın olan membranlar perfluoro sülfonik asit membranlardır. Ancak bu membranların yüksek sıcaklıkta proton iletkenliği düşüktür ve çok pahalıdır. Bu nedenle çalışmalar alternatif membranlar arayışı üzerine yoğunlaşmıştır. Bu çalışmada Nafion® içerikli membrana göre daha iyi fiziksel ve kimyasal özelliklere sahip, hem organik hem de inorganik yapıyı bir arada bulunduran kompozit membran sentezi amaçlanmıştır. Yapılan çalışmada borik asit bazlı sülfonlanmış polistiren/polivinil alkol kompozit membranı ve boron fosfat bazlı sülfonlanmış polistiren/polivinil alkol kompozit membranı sentezlenmiştir. Sentezlenen membranlar su tutma kapasitesi, kalınlık ölçümleri, Taramalı Elektron Mikroskobu (SEM) analizleri, Fourier Dönüşüm Kızıl Ötesi Spektroskopisi (FT-IR), iyon değiştirme kapasitesi (IEC), termalgravimetrik analiz (TGA) ve elektrokimyasal empedans ölçümleri gibi karakterizasyon deneylerine tabi tutulmuştur. Çalışmaların sonucunda SPS-PVA-9BP kodlu membranın diğer membranlara göre daha yüksek proton iletkenliği (0,047 mS/cm), iyon değiştirme kapasitesi (1.46 meq/g) ve su tutma kapasitesine (%20.78) sahip olduğu belirlenmiştir. Literatürede rapor edilen değerler ve çalışma kapsamında edinilen bilgilere dayanılarak bu özelliklere sahip bir membran yakıt hücrelerinde elektrolit olarak kullanıma uygundur olduğu düşünülmektedir.

Synthesis and characterization of sulphonated polystyrene/polyvinyl alcohol composite membrane with boric acid and boron phosphate support

Polymer Electrolyte Fuel Cells (PEMFC) are the most promising energy source candidate due to their excellent properties such as ease of their operation and maintenance, having high energy density, having higher efficiency than the internal combustion engines and their non-toxic emission. Proton exchange membrane is regarded as the heart of the PEMFC. Today, perfluoro sulfonic acid membranes are the most widely used membranes. However proton conductivity of these membranes is very small at high temperatures and they are very expensive. Therefore studies have been focused on the investigation of alternative membranes. In this study, it is aimed to synthesize an organic-inorganic composite membrane that has better properties than the Nafion® membrane. The synthesis of sulfonated polystyrene/polyvinyl alcohol composite membranes with different additives namely, boron phosphate or boric acid were carried out. Also these membranes were subjected to the characterization experiments such as, determination of water uptake capacity and ion exchange capacity, thickness measurements, Scanning electron microscope (SEM), FT-IR, Thermorgravimetric analysis and electrochemical impedance analysis (EIS). As a result of all these studies it was determined that the membrane coded as SPS-PVA-9PB has the highest proton conductivity (0.047 mS/cm), ion exchange capacity (1.46 meq/g) and water uptake (%20.78). Regarding the values reported in the literature and depending on the knowledge gained during the fuel cell studies it was concluded that any membrane which has the above properties is suitable for the fuel cell applications.

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