Steaming‐Assisted Conversion: A New Strategy for the Synthesis of Anatase TiO₂, Nb, and W‐doped Anatase TiO₂ 2D Inverse Opal Films

Abstract Steaming‐assisted conversion route, a new strategy, is first adapted for the synthesis of highly crystallized anatase TiO₂ 2D inverse opal (IO) monolayer films, and then to Nb‐doped TiO₂ and W‐doped TiO₂ 2D IO monolayer films. Pure water, ammonia, or HCl solutions are used as a source of steaming vapor to convert dry films of amorphous TiO₂ IO, NbCl₅/TiO₂, and WCl₆/TiO₂ composite IOs into anatase TiO₂, Nb‐doped TiO₂, and W‐doped TiO₂ IO films. This new strategy renders possible the doping of metal ions within the framework of the anatase TiO₂ IO films under low temperature and liquid‐free conditions. Further, the ordered array structure of the IO films is also effectively retained. The low steaming conversion temperature allows high dopant rates of homogeneously distributed heteroatoms, resulting in Nb doping as high as ≈34%. The thus prepared TiO₂, Nb‐doped TiO₂, and W‐doped TiO₂ anatase IO films are successfully used as active electrodes in the fabrication of electrochromic devices.