Multifunctional Materials for Energy Storage and Oxygen Evolution: Tungsten and Molybdenum Doped Titanium Niobium Oxide

Sammanfattning

As the demand for sustainable and efficient energy systems continues to grow, integrated energy solutions have sparked interest in materials that combine multiple functionalities within a single structure. Rather than serving a single purpose, such materials could store energy, catalyse chemical reactions, and even exhibit optical changes, enabling novel applications in smart devices and material repurposing. This thesis investigates titanium niobium oxides (TNOs) doped with molybdenum (Mo) and tungsten (W), focusing on their potential for lithium-ion energy storage and catalytic activity in the oxygen evolution reaction (OER). The synthesized TNOs exhibited distinct functional behaviours depending on the dopant. Mo doping resulted in enhanced electrochemical performance, suggesting improved conductivity and a shift in the energy storage mechanism from intercalation to capacitive behaviour at higher sweep rates. In contrast, among the three samples, the W-doped TNOs demonstrated superior catalytic efficiency for the OER possibly due to residual WO3 or surface lattice strain induced by W incorporation. Potential electrochromic properties were also investigated on an ad hoc basis, but conclusive results could not be obtained due to limited equipment for through testing. These findings reveal a trade-off between energy storage and catalytic performance, underscoring the potential and importance of compositional tuning. Although combining both functionalities in a single optimized material remains a challenge, Mo- and W-doped TNOs show promising properties as multifunctional electrodes.