Controllable Synthesis of Inverse Opal TiO2‐x Photonic Crystals and Their Photoelectric Properties

In this study, inverse opal TiO_2‐x photonic crystals (IO‐TiO_2‐x) have been successfully synthesized by a two‐step calcination. The whole synthesis is safe and feasible. Additionly, the reduction degree and the structure of IO‐TiO_2‐x can be precisely controlled. A series of IO‐TiO_2‐x samples with different reduction degree were prepared and characterized. The TEM images show that the obtained samples possess a 3D‐ordered macroporous inverse opal structure. The reduced Ti atoms/oxygen vacancies were confirmed by Raman and XPS spectroscopy. All IO‐TiO_2‐x samples showed better photoelectric properties than those of common TiO₂ which indicates their great potential to be applied to photoelectric fields. The improvement of photoelectric properties is attributed to the efficient electron‐hole separation efficiency induced by moderately reduced Ti atoms/oxygen vacancies. Meanwhile, the 3D‐ordered macroporous inverse opal structure and the band gap are regulated to “capture” more solar energy. This new approach is proven to be a meaningful method to synthesize high‐performance TiO₂ materials.