Preparation of TiO2-Ag heterostructure via tannic acid-assistance and its immobilization on PVDF membrane for the degradation of dye under visible light

•A PVDF-TiO2@Ag hybrid membrane was constructed using TA as a reductant and linker.•The smaller size and uniform distribution of the Ag nanoparticles improved photoactivity.•The stability was maintained by covalent immobilization between TiO2@Ag and the matrix.•The formation conditions of TiO2@Ag were optimized and the maximum η was predicted.•The impact of size, number, and distribution of Ag on photoactivity was examined.