Structure–Application Mapping of Sol–Gel Synthesized variants of TiO₂ Nanoparticles: Linking Crystallite Size, Strain, and Morphology to Photocatalysis, Gas Sensing, and Energy Devices

Some of the more traditional applications of titanium dioxide (TiO₂) nanoparticles include the use of nanoparticles in coatings, gas sensing, photocatalysis, and numerous electrochemical devices. And yet, it remains a challenge to directly relate functional potential and nanostructural descriptors to parameters of synthetic method used. This study made it possible to systematically examine the structures and properties of titanium dioxide nanoparticles synthesized by the sol-gel method through five variants of the processing schedule. In order to determine the relations between synthesis and structural and morphological parameters, the samples were characterized by X-ray Diffraction (XRD and FE-SEM microscopy) and various metrics such as Scherrer’s Crystallite Size equation, Williamson Hall analysis, dislocation density, texture coefficients, and lattice refinements. The results indicate that closer spacing of defects, smaller crystallites having high surface area and high strain are more favorable for gas-sensing performance, while higher photocatalytic activity and hydrogen evolution are easier to achieve. In contrast, coatings, as well as energy storage electrodes are sustained by larger, more stable grains. This description offers a relative starting point for setting a logical design approach to custom-tailore TiO₂ nanoparticles in relation to a specific technology while maintaining a synthesis-structure-application design framework.