Porous graphene and graphene-silica microparticles containing titania nanoparticles were synthesized by emulsion-assisted self-assembly for the photocatalytic decomposition of methylene blue in an aqueous medium. After the mixed dispersion of graphene nanosheets and titania nanoparticles with or without silicic acid was prepared, the complex fluid was emulsified in a continuous oil phase to form tiny droplets that act as micro-reactors for the synthesis of porous photocatalytic particles, the morphology of which was three-dimensional spherical shapes with a number of irregular-shaped macropores. The three dimensional conductive graphene scaffolds greatly enhanced the photocatalytic activity of the porous particles due to the suppression of the recombination of electron-hole pairs generated from titania under UV light irradiation, and adsorption of dye molecules on graphene-silica scaffolds caused rapid removal of aqueous contaminants. Unlike previous reports, the kinetics of the photocatalytic decomposition reaction could not be explained by Langmuir-Hinshelwood kinetics, but the experimental data could be fitted well by the second- or third-order kinetics. This indicates that the removal rate of the pollutant could be enhanced by the supporting material. The removal efficiency of methylene blue was estimated as more than 95% when sufficient amount of the photocatalytic particles was used, implying that application to water treatment process will be possible.

中文翻译：

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紫外光下三维多孔石墨烯-二氧化钛微粒光催化降解亚甲基蓝

通过乳液辅助自组装合成了多孔石墨烯和含有二氧化钛纳米颗粒的石墨烯-二氧化硅微粒，用于在水性介质中光催化分解亚甲蓝。制备出含或不含硅酸的石墨烯纳米片和二氧化钛纳米颗粒的混合分散液后，将复合流体在连续油相中乳化，形成微小液滴作为微反应器合成多孔光催化颗粒，其形貌为是具有许多不规则形状的大孔的三维球形形状。三维导电石墨烯支架由于抑制了二氧化钛在紫外光照射下产生的电子-空穴对的复合，大大增强了多孔颗粒的光催化活性，和染料分子在石墨烯-二氧化硅支架上的吸附导致水性污染物的快速去除。与之前的报道不同，光催化分解反应的动力学不能用 Langmuir-Hinshelwood 动力学来解释，但实验数据可以很好地由二级或三级动力学拟合。这表明支持材料可以提高污染物的去除率。当使用足够量的光催化颗粒时，亚甲蓝的去除效率估计超过 95%，这意味着应用到水处理过程中是可能的。光催化分解反应的动力学不能用 Langmuir-Hinshelwood 动力学解释，但实验数据可以用二级或三级动力学很好地拟合。这表明支持材料可以提高污染物的去除率。当使用足够量的光催化颗粒时，亚甲蓝的去除效率估计超过 95%，这意味着应用到水处理过程中是可能的。光催化分解反应的动力学不能用 Langmuir-Hinshelwood 动力学解释，但实验数据可以用二级或三级动力学很好地拟合。这表明支持材料可以提高污染物的去除率。当使用足够量的光催化颗粒时，亚甲蓝的去除效率估计超过 95%，这意味着应用到水处理过程中是可能的。