(744j) EXAFS Analysis to Elucidate Structure-Property Relationship of ALD-Grown (Ti,Mn)Ox Multifunctional Coatings

Titanium dioxide, TiO₂, is an important catalytic material. Most relevant to work in electrocatalysis is its application as a multifunctional coating, capable of electronic tuning and imparting increased stability. Modification of TiO₂ through the intentional introduction of transition metals allows for control over parameters band structure and sub-surface active sites. A tunable intermediate band was formed in ALD-grown TiO2 thin films through supercycles of MnOx and TiO₂ and modified through control of post treatment processing.

The titanium manganese oxide (TiMnO_x) thin films grown using atomic layer deposition are distinct from binary metal oxides previously reported and have substantial Ti-O-Mn interaction. The annealed films crystallized into Rutile TiO₂ instead of the Anatase phase of films without Mn dopants. X-ray absorption spectroscopy allows for element specific probing of the local chemical environment. XANES revealed a change in the Mn oxidation state prior to crystallization of amorphous TiO₂ into Rutile. EXAFS analysis reveals that the Mn microstructure is dependent on annealing temperature, availability of O₂ during annealing, and overall mass loading. Insights from the microstructure analysis were used to explain electrochemical behavior and create guiding principles for coating development.