Metal-TiO2 nanowires for electrochemical applications
Single-crystalline TiO2 nanowires are utilized as stable support for metal electrocatalysts. The local structure, impurity traces, and interactions between the metal and the TiO2 support are analysed by electron microscopy and atom probe tomography. These analyses are correlated to the electrochemical activity and stability, effectively establishing structure-property relationships at sub-nanometer scale.
Metal oxides possess high chemical stability, which make them attractive supports for metal electrocatalysts. However, the final properties of the supported catalysts depend on several parameters such as the local structure, chemistry and interactions between the metal and the support. Thus, efficient design of supported catalysts requires systematic studies to define the structure-property relationships at the sub-nanometer scale.
This project focuses on the hydrothermal synthesis and structural investigation of highly crystalline metal-TiO2 nanowire arrays as catalyst support material. The TiO2 nanowires are further modified by reductive annealing and etching processes with the aim to improve their conductivity and enhance their surface area. On the resulting hollow nanowires, noble metal catalysts such as platinum and iridium are deposited.
The structure and chemistry of the metal-TiO2 nanostructures are analysed by advanced (scanning) transmission electron microscopy ((S)TEM), energy dispersive X-ray (EDS) and electron energy loss spectroscopy (EELS) techniques before and after electrochemical testing of the materials. Atom probe tomography (APT) is used to unravel trace impurities from the synthesis procedure, which are also affecting the properties of the materials. Such effects of the local structure and chemistry are correlated to the electrochemical activity and stability of the nanomaterials for applications in electrocatalysis and electrochromic devices.
