Formation and stabilisation mechanisms of defects in carbon-doped and self-doped titanate nanotubes

钛酸盐纳米管（TNT）是一种已知的无机氧化纳米管，可以通过掺杂碳来获得C-TNT，从而改变材料的电行为。在提案中描述的c - tnt的合成过程确保了一个高比表面积可以达到。因此，掺杂的纳米管满足PEM燃料电池催化剂支持的规格，如高表面积和高电子导电性。然而，合成过程背后的机制和高电导率的来源至今尚未明确。在合成过程中，氧化钛在热碱性水溶液中进行处理。经过一定的处理时间，钛酸盐纳米管可以从溶液中分离出来。管的形成过程仍有争议。提出了一种剥落滚动机制以及溶解和沉淀机制。纳米管的合成和性能是可重复的，但需要进一步的研究工作来了解其工艺和材料性能。该项目的目标是进一步了解碳掺杂钛酸盐纳米管的结构和结构形成。主要问题是：碳是如何被纳入前驱体粉末和纳米管的？钛的氧化态与碳、结构中的点缺陷之间是否存在协同作用？结构上的什么变化导致了纳米管材料的电子导电性增强？所获得的结果可能对催化剂和催化剂载体的进一步发展产生影响，不仅对燃料电池技术，而且对催化和相关工艺也有影响。我们假设前驱体粉末在碳热处理过程中，在还原气氛中Ti4+被还原为Ti3+，碳原子形成氧空位并稳定氧空位。在我们的实验方法中，在700 - 800℃的温度下，TiO2粉末的碳热处理过程中，由于乙炔的分解，氢存在，这应该引起Ti3+和氧的空位。在氢氧化钠水热处理过程中，这些缺陷是否可以从C-TiO2转移到c - tnt上，以及它们如何影响c - tnt的电学性能是人们非常感兴趣的。计划项目的目标是研究c掺杂氧化钛纳米管，目的是阐明碳在结构中的位置，阐明掺杂物的形成机制及其对C-TNT的影响。

Titanate nanotubes (TNT), are a known type of inorganic, oxidic nanotubes, which can be doped with carbon to achieve C-TNT in order to alter the electric behaviour of the material. The synthesis procedure for C-TNTs described in the proposal ensures that a high specific surface area can be reached. The doped nanotubes thus meet the specifications for PEM fuel cell catalyst support such as high surface area and high electronic conductivity. However, the mechanisms behind the synthesis procedure and the origin of high conductivity are not clarified up to now. During the synthesis process, titanium oxide is treated in hot aqueous alkaline solution. After a certain process time, titanate nanotubes can be separated from the solution. The formation process of the tubes is still discussed controversially. A peeling scrolling mechanism is suggested as well as dissolution and precipitation. The synthesis and properties of the nanotubes is reproducible but further research work is necessary to understand the process and the material properties. The goal of the project is to provide further insight into the structure and structure formation of carbon-doped titanate nanotubes. Main questions are: How is carbon incorporated into the precursor powder and in the nanotubes? Is there any cooperative effect between titanium oxidation state, carbon and point defects in the structure? What changes in the structure are responsible for the enhanced electronic conductivity of the nanotube material? Results obtained could have impact on the further development of catalysts and catalyst supports, not only for fuel cell technology but also for catalysis and related processes in general.We assume that in reducing atmosphere during carbothermal treatment of the precursor powder Ti4+ species are reduced to Ti3+ and oxygen vacancies are formed and stabilised by carbon atoms. In our experimental approach, hydrogen is present due to the decomposition of acetylene during the carbothermal treatment of TiO2 powders at temperatures 700 – 800 °C, which should provoke Ti3+ species and oxygen vacancies.It is of great interest whether such defects can be transferred from C-TiO2 to C-TNTs during hydrothermal treatment in sodium hydroxide and how they affect the electrical properties of C-TNTs. The objective of the planned project is the investigation of C-doped titanium oxide nanotubes, with the goal to elucidate the location of the carbon in the structure and to clarify the formation mechanism with respect to the dopant and their influence on the C-TNT.