Influence of a pressure induced piezoelectric field on the recombination processes in photocatalytically active nanoparticles

压力诱导压电场对光催化活性纳米颗粒复合过程的影响

• 批准号: 249762625
• 负责人: Professor Dr.-Ing. Frank. A. Müller
• 金额: --
• 依托单位: Lehrstuhl für Oberflächen- und Grenzflächentechnologien
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/249762625?language=en
• 关键词: Influence; pressure; induced; piezoelectric; field

Photocatalysis with semiconductor materials requires the excitation of free electrons and holes due to the absorption of light. At the surface of the semiconductor they can be utilized to generate hydroxyl radicals, which take part at chemical reactions in so called advanced oxidation processes (AOP) e.g. for air and water purification. Photocatalysis can thus eliminate pollutants, which can neither be filtered nor degraded biologically by conventional methods. The efficiency of these photocatalysts can be enhanced using nanoscale semiconductor particles, which are characterized by their large specific surface area. However, since no natural driving force for the separation of electrons and holes exists inside the particles, recombination processes cause a significant reduction of the photocatalytic efficiency. The suppression of these recombination processes thus represents a promising approach to produce photocatalysts with significantly improved efficiency. As a result low cost and environmentally friendly constructions can be realized without adding environmentally harmful chemicals during water treatment. In the present research project a well-defined external driving force (pressure) is impressed to nanoscale piezoelectric photocatalytic systems (e.g. ZnO, CdS) inducing an electrical field inside the particles. This electrical field not only separates the electrons and holes spatially, but also transports them from inside to opposite surface areas where they are available for photocatalytic processes. Besides decreasing the recombination probability and increasing the catalytic activity, chemical back reactions of the reactants is also significantly inhibited by the spatial separation. These effects shall be detected by pressure dependent photoluminescence (recombination) as well as photocatalytic activity.

半导体材料的光催化需要由于光吸收而激发游离电子和孔。在半导体的表面上，它们可用于产生羟基自由基，这些自由基在所谓的晚期氧化过程中参与化学反应（AOP），例如用于空气和水净化。因此，光催化可以消除污染物，污染物既不能被传统方法过滤也不能在生物学上降解。这些光催化剂的效率可以使用纳米级半导体颗粒来提高，这些颗粒的特征是它们的大特定表面积。但是，由于颗粒内部没有天然驱动力来分离电子和孔，因此重组过程会导致光催化效率显着降低。因此，这些重组过程的抑制代表了一种有希望的方法来产生具有显着提高效率的光催化剂。结果，可以在不添加水处理期间的环境有害化学物质的情况下实现低成本和环保建筑。在本研究项目中，定义明确的外部驱动力（压力）给纳米级压电光催化系统（例如ZnO，CDS）留下了深刻的印象，该系统诱导了颗粒内部的电场。该电场不仅在空间上分离电子和孔，而且还将它们从内部到相对的表面区域运输到可用于光催化过程的相对区域。除了降低重组概率并增加了催化活性外，反应物的化学背反应也受到空间分离的显着抑制。这些影响应通过依赖压力的光致发光（重组）以及光催化活性来检测。