Key Factor Study for Amphiphilic Block Copolymer-Templated Mesoporous SnO₂ Thin Film Synthesis: Influence of Solvent and Catalyst

As a crucial material in the field of energy storage, SnO₂ thin films are widely applied in daily life and have been in the focus of scientific research. Compared to the planar counterpart, mesoporous SnO₂ thin films with high specific surface area possess more attractive physical and chemical properties. In the present work, a novel amphiphilic block copolymer-assisted sol–gel chemistry is utilized for the synthesis of porous tin oxide (SnO₂). Two key factors for the sol–gel stock solution preparation, the solvent category and the catalyst content, are systematically varied to tune the thin film morphologies. A calcination process is performed to remove the polymer template at 500 °C in ambient conditions. The surface morphology and the buried inner structure are probed with scanning electron microscope and grazing-incidence small-angle X-ray scattering. Crystallinity is characterized by X-ray diffraction. The multi-dimensional characterization results suggest that cassiterite SnO₂ with spherical, cylindrical, and vesicular pore structures are obtained. The variation of the film morphology is governed by the preferential affinity of the utilized solvent mixture and the hydrogen bond interaction between the employed cycloether and H₂O molecules in the solution.