Effect of calcination on structural, morphological and photoelectrochemical performance of SnO2/TiO2 nanostructure films

• 1-D rutile-TiO2 nanoneedles and nanorods were grown on FTO substrates by CBD method.
• Heat treatment leads to the conversion of TiO2 nanoneedles into nanorods.
• Reduction in length and enhancement in diameter upon calcination
• Rutile-TiO2 nanocomposite exhibits excellent stability upon annealing.

In the present work, one dimensional rutile-TiO2nanoneedles (NNs) and nanorods (NRs) were grown directly on transparent conductive fluorine-doped SnO2-coated (FTO) glass substrates by chemical bath deposition (CBD) method using titanium (III) chloride as the precursor, followed by calcination at two different temperatures. The heat treatment leads to the conversion of TiO2 nanoneedles into nanorods with reduction in length and enhancement in diameter. The TiO2 nanostructure displayed a diameter range of 11.3–21.7 nm and a length range of 97.7–55.8 nm. The photoelectrochemical evaluation showed that rutile-TiO2 nanostructure exhibited excellent stability upon annealing in a temperature range of 200–400 °C. Optical studies showed that rutile-TiO2 nanostructure has a high absorption coefficient and a direct band gap. The band gap decreased slightly (3.14–3.03 eV) with increasing calcination temperature. The ease of deposition of rutile-TiO2 nanostructure with different morphologies at low temperature provides a new insight for potential applications in solar cells, sensors, catalysis and separation technology.