Two-steps hydrothermal were demonstrated to create a high efficiently interfacial layer of TiO₂ thin film. The first hydrothermal was conducted to synthesize a well-aligned and compact structure of TiO₂ nanorods on FTO substrate. Etching treatment in an acidic medium of hydrochloric acid (HCl) as a second hydrothermal favors increasing the surface area prior to any deposition to be a heterostructure film. The morphology of nanorods changed while the electrical resistivity decreased, demonstrating that the etching treatment had a substantial effect on the TiO₂ thin film properties. Cyclic voltammetry (CV) was conducted prior deposition. The electrodeposition of Cu₂O on the TiO₂ thin film was fabricated by using copper acetate-based solution with pH value of 12.0 at bath temperature of 60°C. The finding revealed that the pyramidal structure of Cu₂O film was deposited uniformly, which is believed that the properties of TiO₂ interfacial layer were excellently improved.
