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 TiO 2 2D inverse opal (IO) monolayer films, and then to Nb‐doped TiO 2 and W‐doped TiO 2 2D IO monolayer films. Pure water, ammonia, or HCl solutions are used as a source of steaming vapor to convert dry films of amorphous TiO 2 IO, NbCl 5 /TiO 2 , and WCl 6 /TiO 2 composite IOs into anatase TiO 2 , Nb‐doped TiO 2 , and W‐doped TiO 2 IO films. This new strategy renders possible the doping of metal ions within the framework of the anatase TiO 2 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 TiO 2 , Nb‐doped TiO 2 , and W‐doped TiO 2 anatase IO films are successfully used as active electrodes in the fabrication of electrochromic devices.