Adjustment of the Band Gap Energies of Biostabilized CdS Nanoparticles by Application of Statistical Design of Experiments

Abstract

The colloidal synthesis of CdS nanoparticles with the biostabilizers cysteine and glutathione, respectively, at pH values ranging from 4 to 10 is described. For the adjustment of their UV/Vis absorption properties and hence their band gap energies, the Statistical Design of Experiments (DoE) was used. This method allows the simultaneous variation of the synthesis parameters in a systematic manner, and thereby synergistic interaction effects can be obtained. The band gap energies of the quantum dots can be tuned from 3.32 to 4.26 eV by varying kind and concentration of stabilizer, pH value, and concentration of sulfide source. The energy position is significantly dependent on the interaction between the pH value and the concentration of the stabilizer, and the effect of high glutathione concentration is opposite at acidic and alkaline conditions thus leading to band gaps of 4.10 eV at pH = 6 and of 3.64 eV at pH = 10. Examples for the synthesis of semiconductor nanoparticles with predefined spectroscopic properties and preset preparation conditions, e.g., alkaline conditions for the implementation of acid-sensitive dopants, are given.

Biomolecule-controlled hydrothermal synthesis of C–N–S-tridoped TiO2 nanocrystalline photocatalysts for NO removal under simulated solar light irradiation

“…For instance, Qian and coworkers synthesized antimony sulfide nanowires in the presence of cysteine [28]. Cysteine and glutathione were also used to prepare biostabilized CdS nanoparticles [29]. Zhang et al synthesized the porous spongelike Ni 3 S 2 nanostructures on Ni foil substrate with high electrochemical activity [30] and Bi 2 S 3 flowerlike patterns with well-aligned nanorods in the presence of cysteine [31].…”

Controllable synthesis and cell-imaging studies on CdTe quantum dots together capped by glutathione and thioglycolic acid

“…Compared with these QDs, CdTe QDs were comparably better. However, to some extent, the methods of synthesizing the water-soluble luminescent CdTe QDs capped by glutathione, L-cysteine, and mercaptocarboxylic acids can be improved [11,12].…”

Enzyme mediated synthesis of phytochelatin-capped CdS nanocrystals

“…6,7 QDs are typically synthesized in an organic solvent at high temperature resulting in hydrophobic nanoparticles coated with organic capping ligands such as trioctylphosphine oxide that are not suitable for biological applications. [9][10][11][12] The resulting nanocrystals are water soluble and have excellent biocompatibility for use in biological imaging. [9][10][11][12] The resulting nanocrystals are water soluble and have excellent biocompatibility for use in biological imaging.…”