Mesoporous architecture of TiO₂ microspheres via controlled template assisted route and their photoelectrochemical properties

Anatase titanium dioxide (TiO₂) microspheres were successfully synthesized via a controlled chemical route using carbon spheres as sacrificial templates. The morphology has been controlled by varying the deposition time of carbonaceous (c) spheres from 4 to 16 h with the interval of 4 h, which affect the size of TiO₂ spheres. The structural, morphological, optical, compositional and photoelectrochemical properties of the TiO₂ thin films were studied. X-ray diffraction (XRD) pattern confirms the formation of anatase TiO₂ with the tetragonal crystal structure. Field emission scanning electron microscopy analysis revealed that the synthesized anatase TiO₂ microspheres has average diameter of ~330–510 nm. The blueshift in optical absorption is observed due to Mie scattering. The indirect optical band gap energy of TiO₂ was varied over 3.05–3.16 eV, with the increase in deposition time. The HRTEM and SAED results show the polycrystalline nature of the sample which is in good agreement with the XRD. The anatase TiO₂ hollow spheres with mesoporous walls and high specific surface area i.e. 41 m² g⁻¹ was obtained using this simple method. The films were photoelectrochemically active with maximum current density 531 µA/cm² under 100 mW/cm² illuminations.