Moisture-Induced Degradation of Quantum-Sized Semiconductor Nanocrystals through Amorphous Intermediates

Abstract

Elucidating the water-induced degradation mechanism ofquantum-sizedsemiconductor nanocrystals is an important prerequisite for theirpractical application because they are vulnerable to moisture comparedto their bulk counterparts. In-situ liquid-phasetransmission electron microscopy is a desired method for studyingnanocrystal degradation, and it has recently gained technical advancement.Herein, the moisture-induced degradation of semiconductor nanocrystalsis investigated using graphene double-liquid-layer cells that cancontrol the initiation of reactions. Crystalline and noncrystallinedomains of quantum-sized CdS nanorods are clearly distinguished duringtheir decomposition with atomic-scale imaging capability of the developedliquid cells. The results reveal that the decomposition process ismediated by the involvement of the amorphous-phase formation, whichis different from conventional nanocrystal etching. The reaction canproceed without the electron beam, suggesting that the amorphous-phase-mediateddecomposition is induced by water. Our study discloses unexploredaspects of moisture-induced deformation pathways of semiconductornanocrystals, involving amorphous intermediates.