Silica encapsulation of thiol-stabilized lead selenide (PbSe) quantum dots in aqueous solution

• This work describes silica encapsulation of water-soluble PbSe QDs.
• Stability of Pb–thiolate complexes affects surface modification and deposition of silica.
• TGA-stabilized PbSe QDs possess better stability for encapsulating multiple QDs in silica.
• The silica encapsulated PbSe QDs maintain colloidal stability for months.

Silica encapsulation of lead selenide quantum dots (PbSe QDs) in aqueous solution is reported. Thioglycolic acid (TGA) stabilized PbSe QDs were modified with 3-mercaptopropyl trimethoxysilane (MPS) through vigorous stirring in water for 18–24 h in alkaline solution (pH 10.4–10.6). Silica shell was developed by controlled deposition and precipitation of silicates from sodium silicate solution onto MPS modified QDs surfaces. TEM images showed multiple PbSe QDs encapsulated in silica shell. The size of PbSe–SiO2 core–shell nanocrystals was estimated to be 25–30 nm by TEM. Elemental compositions (Pb, Se and Si) were investigated by EDX analysis. The purified colloids of PbSe–SiO2 QDs were stable for months when kept at 4 °C.

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