Nanoparticle high-speed coating

A method of electrostatically coating nanoparticles, comprising:

• a step S100 of preparing a dispersion solution including nanoparticles and a buffer solution, wherein the nanoparticles are negatively charged and a substrate is formed of a material having a surface potential that is pH responsive;
• a step S200 of adding an acid to the dispersion solution to lower a pH of the solution to a pH in the range of about 2.2 to about 4.0, wherein the addition of the acid causes hydroxyl groups to dissociate from a surface of the substrate, thereby reversing a sign of the surface potential of the substrate from negative to positive;
• a step S300 of coating the nanoparticles on the substrate, wherein the coating is driven by electrostatic attraction between the positively charged substrate surface;
• and the negatively charged nanoparticles;
• and
• a step S400 of removing the dispersion solution from the coated substrate,
• wherein a buffering action of the buffer solution is weakened within the pH range of about 2.2 to about 4.0, thereby causing the nanoparticles to assemble into molecular clusters including at least one of dimers, trimers, and oligomeric forms.