Preparation Of SrTiO₃ And K₂La₂Ti₃O₁₀ Photocatalysts And Their Applicatios In Photo-rechargeable Hydrogen Storage Electrodes

In this paper, the preparation of SrTiO₃ and K₂La₂Ti₃O₁₀ photocatalysts and their applications in photochargeable hydrogen storage alloy electrodes have been investigated.By using Sr(NO₃)₂ and Ti(OBu)₄ as raw materials, nano-sizedSrTiO3 powder was prepared by the sol-gel process. By means of IR, TG-DTA, XRD, SEM and UV analysis, the different factors affecting the sol-gel process were investigated, and the crystal structure and characteristics of the as-prepared SrTiO₃ powder were analyzed. The experimental results showed that the factors including alcohol, acetic acid, water, propyl alcohol, temperature and PH value have obvious influence in sol-gel process, especially, in which the reaction temperature is the most important factor for the gelation time and quality of the gel. Perovskite SrTiO₃ is formed at a heat treatment temperature of 650℃. As the increase of heat treatment temperature, the phase abundance of SrTiO₃ is improved and the size of SrTiO₃ crystal grows as well. A red shift phenomenon is observed in UV spectrum for the corresponding powder.By using stearic acid, La(NO₃)₃, K₂CO₃ and Ti(OBu)₄ as raw materials, a polymerized complex combustion method was applied to synthesize the ultra-fine perovskite-type layered compound K₂La₂Ti₃O₁₀. By means of TG-DTA, XRD, SEM and UV analysis, the effects of some factors such as organic additives, K2CO3, temperature and heat treatment on the preparation process of K₂La₂Ti₃O₁₀ powder were investigated. The results showed that the amount of K₂CO₃ and temperature of heat treatment were the major factors affecting the powder composition.The size distribution of K₂La₂Ti₃O₁₀ is in the range of 200³00 nm.The photo-rechargeable electrodes were prepared by modifying SrTiO₃ and K₂La₂Ti₃O₁₀ photocatalysts on the surface of the hydrogen storage alloys(HSA). The results showed that the maximum discharge capacity of HSA modified with SrTiO₃ is about 6.94 mAh/g and 9.36 mAh/g for K₂La₂Ti₃O₁₀ at the discharge current of 10 mA/g of the discharge current after 6h photocharging. After photocharging, the corresponding potential of the above two electrodes shifts negatively up to -0.70 and -0.76 V (vs.Hg/HgO), respectively. The photocharging process may be explained by two possible mechanisms, namely photo- electrocatalytic hydrogen storage mechanism and photocatalytic hydrogen storage mechanism. Both HSA electrodes modified with nano-sized SrTiO₃ and K₂La₂Ti₃O₁₀ photocatalysts exhibit obvious photochargeability.