Stabilization of photoelectrochemically highly reactive anatase structures with defect-rich surfaces

锐钛矿向金红石的转变伴随着富含缺陷的缺氧TiO2-x表面，但其表现出较高的反应活性。因此，初步研究表明，通过控制合成和鉴定纳米二氧化钛颗粒的同源序列，多分散热原TiO2材料的光电效率直接受到特定锐钛矿颗粒分数的控制，该分数具有最接近锐钛矿向金红石转化的特征。由于它们的热稳定性差，这些高活性锐钛矿结构的比例非常小。因此，本研究项目的重点是研究高活性锐钛矿组分在气体-气溶胶流动中形成和稳定的基本机制。这包括以知识为基础的纳米材料合成，其中粒子结构将通过淬火系统地变化，即在其结构中冻结。在工艺工程方面，本项目旨在阐明颗粒在火焰中生长的条件与多晶热原光催化剂的高活性锐钛矿组分的演变之间的关系。从材料科学的角度来看，可以使用多分散二氧化钛粉末的分数分析和光催化过程参数的变化来研究氧化反应的动力学，作为表面吸附和消耗氧气的光化学过程的等效，即跟踪氧空位的浓度作为粒度及其在锐钛矿-金红石图上的位置的函数。缺陷结构和光催化性能的相互关系将通过汇集申请人在工艺技术和材料科学领域的专业知识以及结合互补的实验和分析方法来实现。特别是跨学科的知识转移和中期结果的反馈将采用模块化结构化的工作计划。

The anatase-to-rutile transformation is accompanied with defect-rich oxygen-deficient TiO2-x surfaces, which nevertheless exhibit high reactivity. Thus, preliminary studies showed that using controlled synthesis and identifying homologous sequences of titania nano-particles, the photoelectrochemical efficiency of polydis-perse pyrogenic TiO2 materials is directly controlled by a specific anatase particle fraction, which have the characteristics of being closest to the anatase-to-rutile transformation. Due to their poor thermal stability the fraction of these highly reactive anatase stuctures is very small. Therefore, the research project is focused on the study of the fundamental mechanisms contributing to the formation and stabilization of the highly reactive anatase fraction in the gas-aerosol flow. This includes a knowledge-based synthesis of the nano-materials, in which particle structures will be varied systematically by quenching, i.e. freezing-in their structure. With respect to process engineering this project aims in clarifying the relationships between the conditions of particle growth in the flame and the evolution of the highly-active anatase fraction of polycrystalline pyrogenic photocatalysts. In view of material science it is plant to use the fractional analysis of polydisperse TiO2-powders as well as a variation of photocatalytic process parameters in order to study the kinetics of the oxidation reaction as an equivalent to the photochemical processes at the surface with respect to adsorption and consumption of oxygen, i.e. tracking the concentration of oxygen vacancies as function of the particle size and its location on the anatase-rutile diagram. The interrelation of defect structures and phpotocatalytic performance will be achieved by bringing together the expertise of the applicants in the fields of process technology and materials science as well as by combining complementary experimental and analytic metoods. In particular, cross-disciplinary knowledge transfer and feedback of interim results will be used to adopt the modular structured working program.