Cappelluti M Davide, Hadzifejzovic Emina, Foord John S, Gregory Duncan H
School of Chemistry, University of Glasgow University Avenue Glasgow G12 8QQ UK
School of Engineering, University of Glasgow Oakfield Avenue Glasgow G12 8LT UK.
RSC Adv. 2020 Oct 8;10(61):37233-37245. doi: 10.1039/d0ra05796g. eCollection 2020 Oct 7.
The synthesis of nanostructured sub-microspheres of TiO anatase with hierarchical nano- and mesoporosity was successfully achieved by using an innovative approach that applies the principles of acidic digestion to microwave (MW) solvothermal synthesis. This process, termed flash microwave-assisted solvothermal (FMS) synthesis, facilitates the formation of spherical particles without surfactants or templating agents, exploiting the rapid reaction kinetics engendered by MW heating. Unlike many other MW-assisted solvothermal methods, the application of constant MW power leads to a rapid increase of the autogenous pressure, inducing burst-nucleation of small primary crystallites and subsequent rapid agglomeration into secondary particles, with reaction times reduced to minute-timescales. The use of non-aqueous polar solvents such as ethanol is key to the production of regular spheres with a narrow size distribution, composed of nanocrystallites. Morphology, porosity, specific surface area, phase composition, crystallite size and optical properties of the particles can be controlled a judicious selection of physical and chemical synthesis parameters, especially precursor choice and acid concentration. The complex structure of the particles leads to surface areas of up to 500 m g with intergranular mesoporosity. The as-synthesised FMS particles show increased adsorption under dark conditions and selective de-ethylation of rhodamine B under visible light compared to a commercial photocatalyst (Degussa P25). The photodegradation mechanism hinges on the capacity of the spheres to accept electrons from the photoexcited state of molecules at the particle surface, with the large sphere surface area maximising adsorption capacity and improving the efficiency of the photocatalytic processes. The singular characteristics and properties of the particles could pave the way for further applications in water purification and optoelectronic devices.
通过采用一种创新方法，即将酸性消解原理应用于微波（MW）溶剂热合成，成功实现了具有分级纳米和介孔结构的TiO锐钛矿纳米结构亚微球的合成。这个过程被称为快速微波辅助溶剂热（FMS）合成，它利用MW加热产生的快速反应动力学，在不使用表面活性剂或模板剂的情况下促进球形颗粒的形成。与许多其他MW辅助溶剂热方法不同，恒定MW功率的应用导致自生压力迅速增加，引发小初级微晶的爆发成核以及随后快速团聚成次级颗粒，反应时间缩短至分钟级。使用乙醇等非水极性溶剂是生产由纳米微晶组成、尺寸分布窄的规则球体的关键。通过明智地选择物理和化学合成参数，特别是前驱体选择和酸浓度，可以控制颗粒的形态、孔隙率、比表面积、相组成、微晶尺寸和光学性质。颗粒的复杂结构导致比表面积高达500 m²/g，具有晶间介孔。与商业光催化剂（Degussa P25）相比，合成的FMS颗粒在黑暗条件下显示出增强的吸附能力，在可见光下对罗丹明B具有选择性脱乙基作用。光降解机制取决于球体从颗粒表面分子的光激发态接受电子的能力，大的球体表面积使吸附能力最大化并提高光催化过程的效率。颗粒的独特特性和性能可为水净化和光电器件的进一步应用铺平道路。
