Publication: Investigation of the effect of TiO2 filmcoated on hematite photoanode produced by thermal oxidation on photoelectrochemical (PEC) hydrogen production efficiency
Abstract
Hematit (α-Fe₂O₃), elverişli bant aralığı, doğada yaygın olarak bulunması ve sulu ortamlardaki kararlılığı sebebiyle fotoelektrokimyasal su ayrıştırma yöntemi için umut vaad eden bir adaydır. Bununla birlikte, verimliliği genellikle zayıf yük taşıma özellikleri ve hızlı elektron boşluk rekombinasyonu ile sınırlıdır. Bu özellikleri iyileştirmek ve PEC verimliliğini artırmak amacıyla çeşitli yüzey modifikasyon teknikleri kullanılabilir. Titanyum dioksit kullanılarak yapılan yüzey modifikasyonunun elektron boşluk rekombinasyonunu azaltmak, yük ayrımını iyileştirmek ve hematitin bazı optik özelliklerini optimize etmek gibi olumlu etkileri bulunmaktadır. Bu çalışmanın amacı, titanyum dioksit kaplamanın hematit (α-FeO₃) fotoanotların PEC özellikleri üzerindeki etkisini göstermektir. Hematit numuneleri FTO (Flor katkılı kalay oksit) üzerine elektrokimyasal demir (Fe) biriktirme ve ardından termal oksidasyon işlemi ile üretilmiştir. Daha sonra suda çözünebilen titanyum bazlı bir çözelti kullanılarak hematit yüzeyinde bir TiO₂ tabakası elde edilmiştir. Bu yüzey modifikasyon yöntemi ile hematit fotoanotların PEC verimliliğinin orta derecede arttığı gözlemlenmiştir. Örneklerin PEC karakterizasyonu LSV, OCP ve EIS analizleri ile yapılmış ve ayrıca hematit fotoanot yüzeyinde elde edilen titanyum dioksit tabakasını analiz etmek için XPS ve UV-VIS spektometri analizleri gerçekleştirilmiştir. Yüzey morfolojisinin karakterizasyonu taramalı elektron mikroskobu (SEM) kullanılarak gerçekleştirilmiştir.
The Hematite (α-Fe₂O₃) is a promising candidate for PEC water splitting due to its favorable band gap, abundance, and stability in aqueous environments. However, its efficiency is often limited by poor charge transport properties and rapid electron-hole recombination. To overcome these limitations, various methods can be used such as surface modification tecqniques in order to increase the PEC efficiency. The surface modification with using titanium dioxide has multiple benefits such as reducing electron-hole recombination, improving charge seperation and optimizing some optical properties of the hematite. The aim in this study was to show the effect of titanium dioxide coating on the PEC characteristics of hematite (α-FeO₃) photoanodes. Hematite samples were fabricated on FTO (Fluorine doped tin oxide) through electrochemical deposition of iron (Fe) followed with thermal oxidation process. Afterwards with the use of a water soluable titanium based solution including immersion followed with a heat treatment (calcination a TiO₂ layer have been achieved on the surface of the hematite. It was observed that the PEC efficiency of hematite photoanodes have been moderately increased with this surface modification method. The PEC characterization of the samples have been made with LSV, OCP and EIS measurements and also XPS and UV-VIS spectometry analysis conducted to analyse the titanium dioxide layer achieved on the surface of the hematite photoanode. The characterization of the surface morphology have been conducted with using the scanning electron microscopy (SEM).
The Hematite (α-Fe₂O₃) is a promising candidate for PEC water splitting due to its favorable band gap, abundance, and stability in aqueous environments. However, its efficiency is often limited by poor charge transport properties and rapid electron-hole recombination. To overcome these limitations, various methods can be used such as surface modification tecqniques in order to increase the PEC efficiency. The surface modification with using titanium dioxide has multiple benefits such as reducing electron-hole recombination, improving charge seperation and optimizing some optical properties of the hematite. The aim in this study was to show the effect of titanium dioxide coating on the PEC characteristics of hematite (α-FeO₃) photoanodes. Hematite samples were fabricated on FTO (Fluorine doped tin oxide) through electrochemical deposition of iron (Fe) followed with thermal oxidation process. Afterwards with the use of a water soluable titanium based solution including immersion followed with a heat treatment (calcination a TiO₂ layer have been achieved on the surface of the hematite. It was observed that the PEC efficiency of hematite photoanodes have been moderately increased with this surface modification method. The PEC characterization of the samples have been made with LSV, OCP and EIS measurements and also XPS and UV-VIS spectometry analysis conducted to analyse the titanium dioxide layer achieved on the surface of the hematite photoanode. The characterization of the surface morphology have been conducted with using the scanning electron microscopy (SEM).