Water-splitting using photoelectrodes of titania and titania-perovskite halite composite films
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Water-splitting using photoelectrodes of titania and titania -perovskite halite composite films Yu-Shiuan Lai1, Tao-Wei Yang 1 , Ming-Show Wong1, Yi-Hao Pai 2 , Su-Hua Chen 1 1
Department of Materials Science and Engineering, 2 Department of Opto Electronic Engineering, National Dong Hwa Universit y, Hualien, Taiwan ABSTRACT
Titanium oxide photoelectrodes have been used for water splitting for a few decades, but have low solar-to-hydrogen efficiencies. Perovskite halides (e.g., CH3NH3PbI3) have recently emerged as an efficient light absorber system. We try to combine the two materials to create new photoelectrodes to achieve a higher efficiency for hydrogen production. The photoelectrodes are investigated for water-splitting hydrogen production under Xe light irradiation by photoelectrochemical (PEC) reaction. Since perovskite halides are favorable light harvesters under UV and visible light irradiation, the composite films of titania and perovskite halide would achieve efficient water splitting. The hydrogen production rate using the composite films is higher than that using anatase TiO2 electrode. However, the composite films are not stable in water under light irradiation and the perovskite halide gradually decomposes into lead halide. INTRODUCTION Energy production and environmental challenges are important issues in the 21st century [1]. Limited fossil fuel resources and strict environmental regulations motivate the search for sustainable, efficient and green energy sources [2]. Hydrogen has a great potential as a future energy carrier, especially, if the hydrogen is generated from hydrocarbons and water resources by photoelectrochemical water-splitting process [3-5], which is safe, low-cost and using abundant solar energy. Sunlight in the near-infrared, visible, and ultraviolet regions radiates a tremendous amount of energy and intensity to the earth, so that harnessing this solar energy would contribute significantly to our electrical and energetic needs in daily life [6]. Since Honda and Fujishima [7.8] reported that the H-type water-splitting experiment using semiconducting photoelectrolysis cells, many studies in the photocatalytic water-splitting have been carried out. Photoelectrolysis cells consisting of TiO2 electrode and Pt black electrode are connected through an external load, and the electron-hole pairs generated from the irradiation of TiO2 electrode under UV light, led to the evolution of H2 and O2 on the surface of the Pt electrode and TiO2 electrode, respectively. The group of Anpo [6] modified the cells into the H-type model for photoelectrode of thin film. Perovskite halides (e.g., CH3NH3PbX3) have recently emerged as an efficient light absorber system, leading to solar cell efficiencies above 19%, and have attracted attention as light-harvesting materials for mesoscopic solar cells [9.10]. In addition, the cubic CH3NH3PbI3-xBrx solid-solution perovskite was stable under a humidity test [11.12] In this present paper we try to combine the two materials, TiO2 and CH3NH3PbI3-xBrx to achieve a
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