One-Step Synthesis of Water-Soluble Quantum Dots from Ag₂S and AgInS₂ QDs

Abstract

Water-soluble quantum dots (QDs) have attracted much attention because of their excellent optical stability and biocompatibility. Here we report a simple, easy to operate, safe, and nontoxic method to synthesize water-soluble Ag2S QDs and AgInS2 (AIS) QDs. By addition of l-cysteine to the Ag+ and In3+ precursor solution, the water-soluble Ag2S and AIS QDs can be synthesized through the hydrothermal method. With increased reaction temperatures and times, Ag2S QDs were converted to AIS QDs. The colors were adjusted from green light to red light under UV light. The absorption spectra were red-shifted as a whole with increasing time and temperature. The fluorescence peaks at 80 and 90 °C did not change with time (greater or equal to 2 h), but the fluorescence peaks at 100 °C had a relatively large change from 470 to 650 nm. The band gaps of Ag2S QDs had a large change from 2.2 to 0.9 eV due to crystallinity, and the band gap of the AIS QDs was about 0.9 eV. The photocatalytic H2 production performance was studied. The results indicated that the Ag2S QDs obtained by reaction at 90 °C for 4 h exhibited the greatest amount of H2 production (1240 μmol·g–1·h–1). Finally, the reaction process was also investigated.

Micro-/nano-fluidic devices and in vivo fluorescence imaging based on quantum dots for cytologic diagnosis

“…A simple and safe hydrothermal method for the synthesis of water-soluble AgInS 2 QDs was proposed by Yuan et al and applied to photocatalytic H 2 production. 31 Kameyama et al successfully produced AgInTe 2 NCs by thermal reaction in organic solvent. These rod-shaped NCs with an 18% PL QY were applied to in vivo NIR biological imaging using liposomes.…”

Ternary Quantum Dots in Chemical Analysis. Synthesis and Detection Mechanisms

“…Particle size and maximum emission wavelength are related to the reaction time, showing bathochromic and hyperchromic effects. Nevertheless, microwave and solvothermal syntheses allow obtaining nanoparticles with higher %QY values within a couple of minutes, which is not observed in a reflux system [ 56 ]. Time is the critical factor in the synthesis because it can cause aggregation and oxidation of the precursors, leading to a decrease of the emission signal [ 37 ].…”

Ligand and hard base assisted preparation of AgInS2 single phase nanocrystals for enhancing the photocatalytic activity of TiO2

“…In addition, the monoclinic phase Ag 2 S and cubic phase In 2 S 3 obtained under the same preparation conditions have obvious lattice incompatibility, which makes it difficult for In 3+ to attach into the Ag 2 S cell, which is the main reason for phase separation. Therefore, it is generally necessary to add ligands to combine lattice broken Ag 2 S and In 2 S 3 to form AgInS 2 single phase nanocrystals [33,34]. Generally, the selected ligands are organic compounds containing sulfhydryl groups.…”