Size Reduction of CdSe/ZnS Core-Shell Quantum Dots Photosensitized by Benzophenone: Where Does the Cd(0) Go?

作者：Galian Raquel E^*; de la Guardia Miguel; Perez Prieto Julia

来源：Langmuir, 2011, 27(5): 1942-1945.

DOI：10.1021/la104037y

The size of core shell CdSe/ZnS quantum dots can be decreased by using the combined action of an n,pi* aromatic ketone and UVA light. Energy-dispersive X-ray spectroscopy as well as X-ray photoelectron spectroscopy techniques gave information on the photosensitization mechanism and the eventual destiny of Cd(2+) and Se(2-) core ions. Our data support the electron transfer from the BP ketyl radical to Cd(2+), leading to Cd(0) and H(+), as well as to the recovery of benzophenone. Elemental Cd remains on the core and, eventually, can be oxidized to CdO. In addition. Se(2-)counterions disperse inside the solution mainly attached to protonated amine ligands. The Se(2-) combines with H. leading to SeH(2), which is finally oxidized to Se(0) by oxygen. Therefore, quantum dots illumination in the presence of benzophenones brings about a profound nanoparticle reconstruction which takes place after dark storage; this agrees with the drastic quenching of the quantum dot emission detected immediately after illumination as well as the slow recovery in the dark.

• 出版日期2011-3-1