Titanium dioxide nano-porous coating and preparation method thereof

The invention discloses a titanium dioxide nano-porous coating and a preparation method thereof. The coating comprises a TiO2 nanoparticle porous film which is coated on a substrate and has a thickness of 100-700 nm, wherein the particle size of TiO2 nanoparticles is 20-30 nm, and the diameter of pores in the porous film is 8-10 nm. The preparation method comprises the steps: adding a mixed liquiddropwise to an acidic mixed aqueous solution firstly, wherein the mixed liquid and the acidic mixed aqueous solution are prepared separately; and then performing stirring so as to obtain TiO2 sol, then adding polyvinylpyrrolidone to the TiO2 sol, performing stirring so as to obtain mixed sol, then adding ethanol to the mixed sol, performing dilution and aging so as to obtain coating sol, then immersing a substrate in the coating sol for dip coating, then performing airing, then putting the obtained coated substrate at 480-520 DEG C, performing heat preservation, and then performing cooling soas to obtain the desired