After the core-shell SiO₂@TiO₂ nanoparticles (CSTNs) were synthesized by hydrothermal method, we investigated the influence of different molar ratios of Ti/Si on morphology, structure, and photocatalytic activity of the CSTNs. It was found that the CSTNs showed different size and surface morphology as the Ti/Si molar ratio changed. Besides, the TiO₂ and the CSTN had the anatase phase after hydrothermal process and calcination at 450°C for 2 h. The N₂ adsorption-desorption isotherms demonstrated the CSTNs with the molar ratio of Ti/Si increased from 1 : 1 to 8 : 1 can be categorized as type IV with hysteresis loop of type H2 and showed to be mesoporous materials. In addition, the CSTNs with the Ti/Si molar ratio of 5 : 1 had the highest surface area of 176.79 m²/g. Surface charges showed the isoelectric point (IEP) of the CSTNs ranged between silica (IEP at pH 3.10) and titania (IEP at pH 5.29). Since the molar ratio of Ti/Si increased from 1 : 1 to 8 : 1 by degradating both colorless organic pollutant of phenol and colored substances of methylene blue (MB) under UV irradiation, the photocatalytic activity of CSTNs exhibited higher photodegradation efficiency compared with TiO₂. What is more, the experimental results also showed the CSTNs with Ti/Si molar ratio of 5 : 1 had the highest photocatalytic activity and showed higher photocatalytic efficiency compared with other TiO₂-SiO₂ composites reported for photodegradation of phenol and MB.

中文翻译：

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Ti / Si的摩尔比对光催化应用的核-壳SiO2 @ TiO2纳米粒子的影响

通过水热法合成了核壳SiO ₂ @TiO ₂纳米粒子（CSTN）后，研究了不同摩尔比的Ti / Si对CSTN的形貌，结构和光催化活性的影响。发现随着Ti / Si摩尔比的改变，CSTNs显示出不同的尺寸和表面形态。此外，TiO ₂和CSTN在水热处理和在450℃下煅烧2小时后具有锐钛矿相。N ₂吸附-解吸等温线表明，Ti / Si摩尔比从1：1增加到8：1的CSTN可以归类为IV型，具有H2型磁滞回线，并且是介孔材料。此外，Ti / Si摩尔比为5：1的CSTN的最大表面积为176.79 m ² / g。表面电荷显示CSTN的等电点（IEP）介于二氧化硅（pH 3.10的IEP）和二氧化钛（pH 5.29的IEP）之间。由于通过在紫外线照射下降解苯酚的无色有机污染物和亚甲基蓝（MB）的有色物质，Ti / Si的摩尔比从1：1增至8：1，因此CSTN的光催化活性比TiO更高。₂。此外，实验结果还表明，与报道的其他酚和MB降解的TiO ₂ -SiO ₂复合材料相比，Ti / Si摩尔比为5：1的CSTN具有最高的光催化活性和更高的光催化效率。