Through this project, we have made several important scientific and methodological advances. First, we established that polyoxometalate (POM) structures are indeed involved in hydrothermal synthesis and act as pre-nucleation species. Their presence and configuration at the point of nucleation can determine which binary oxide forms—provided the solvent used stabilizes the POMs. This means that solvent choice plays a crucial role in directing reaction pathways, and we demonstrated that a simple and effective way to control structure formation is by considering how precursor materials behave in different solvents.
Building on this insight, we showed that by controlling the structure of the precursor cluster—particularly through solvent manipulation—we can predict and control which material polymorph forms. This was exemplified in our work on molybdenum oxide, where we successfully synthesized specific crystal structures, nanostructures, and defect densities by selecting targeted synthesis parameters.
Our studies of mixed metal oxides further revealed that dopant incorporation is highly system-dependent. For example, transition metal tungstates require the metal to be integrated into a tungsten-based POM in the precursor state, whereas molybdates do not. In the case of high entropy oxides, we found that synthesis success increases significantly when all constituent metals are incorporated into a single precursor cluster, as this reduces the risk of phase segregation. Given the current strong interest in high entropy materials, we believe our in situ studies offer valuable insights for designing new synthesis strategies.
Finally, we achieved significant methodological progress, particularly in synchrotron-based experimental setups and data analysis. One of our key contributions was the development of automated data analysis methods, which have greatly improved the efficiency and accuracy of interpreting complex datasets in real time.
