High transmittance and superhydrophilicity of porous TiO2/SiO2 bi-layer films without UV irradiation

► Double-layered porous TiO2/SiO2 films were prepared. ► As-prepared porous TiO2/SiO2 bi-layer films have high transmittance. ► Superhydrophilicity of as-prepared film can be obtained without UV illumination.