Method for scalable production of nanoshells using salt assisted purification of intermediate colloid-seeded nanoparticles

A method for treating a suspension containing colloid-seeded nanoparticles and excess metal colloids comprising:

• (a) adding to the suspension a filter aid comprising a salt;
• (b) filtering the suspension with a filter of a pore size intermediate between the average seeded nanoparticle size and the average excess colloid size, so as to form a retentate comprising the majority of the precursors and a filtrate comprising the majority of the excess colloids, wherein the filtering comprises:
• (b1) loading the suspension to a crossflow filtration zone containing the filter;
• and
• (b2) passing a first wash liquid through the filtration zone tangentially to the filter;
• and
• (c) collecting the retentate.

A method for making metallized nanoparticles via intermediate colloid-seeded nanoparticles, comprising:

• (a) providing a suspension of the colloid-seeded nanoparticles, wherein the colloids comprise a first metal;
• (b) adding to the suspension a filter aid comprising a salt;
• (c) filtering the suspension with a filter of a pore size intermediate between the average seeded nanoparticle size and the average excess colloid size, so as to form a retentate comprising the majority of the seeded nanoparticles and a filtrate comprising the majority of the excess colloids;
• (d) collecting the retentate;
• and
• (e) reducing ions of a second metal onto the colloid-seeded nanoparticles so as to form the metallized nanoparticles.