Tuning the Morphology and Exposed Facets of SrTiO₃ Nanostructures for Photocatalytic Dye Degradation and Hydrogen Evolution

This study aims at investigating the role of the dielectric constant of polyols on the size and morphology of SrTiO3 nanostructures and thereby its effect on the photocatalytic performance of the oxide. Herein, among the various available polyols, we have used ethylene glycol (EG), poly(ethylene glycol)-300 (PEG-300), and poly(ethylene glycol)-400 (PEG-400) for our study. The effect of polyols was also compared by taking water as the solvent instead of polyols. We discuss how a change in the synthetic methodology, i.e., change of the solvent, affects the defects, crystallite size, and nature of the facets. We observed that the particle size decreased with an increase in the dielectric constant of the solvent (water and polyols). We also observed that the shape (nanocubes with water, nanocuboids with PEG-400, edge-truncated nanocuboids with PEG-300, and hexagonal-shaped particles assembled to form a flower-like nanostructure with EG as solvent) and nature of the exposed facets were also affected by the dielectric constant of the solvent. The top exposed facet of the synthesized SrTiO3 nanostructures was observed to be [001] (for SrTiO3 nanostructures synthesized using different solvents) with [011̅] facet, as observed for the sample synthesized using EG and PEG-300 as the solvent. The effect of size and shape on their photocatalytic performance (during both photodegradation of Rhodamine B (RhB) and hydrogen evolution) was also evaluated.