Insights into the Structure of Dot@Rod and Dot@Octapod CdSe@CdS Heterostructures

DOI: 10.1021/acs.jpcc.5b04593

Authors: Anna Corrias (University of Kent) , Erika Conca (University of Cagliari) , Giannantonio Cibin (Diamond Light Source) , Gavin Mountjoy (University of Kent) , Diego Gianolio (Diamond Light Source) , Francesco De Donato (Nanochemistry, Istituto Italiano di Tecnologia) , Liberato Manna (Nanochemistry, Istituto Italiano di Tecnologia) , Maria Francesca Casula (University of Cagliari)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Journal Of Physical Chemistry C , VOL 119 (28) , PAGES 16338 - 16348

State: Published (Approved)
Published: July 2015
Diamond Proposal Number(s): 9759

Abstract: CdSe@CdS dot@rods with diameter around 6 nm and length of either 20, 27, or 30 nm and dot@octapods with pod diameters of ∼15 nm and lengths of ∼50 nm were investigated by X-ray absorption spectroscopy. These heterostructures are prepared by seed-mediated routes, where the structure, composition, and morphology of the CdSe nanocrystals used as a seed play key roles in directing the growth of the second semiconducting domain. The local structural environment of all the elements in the CdSe@CdS heterostructures was investigated at the Cd, S, and Se K-edges by taking advantage of the selectivity of X-ray absorption spectroscopy, and was compared to pure reference compounds. We found that the structural features of dot@rods are independent of the size of the rods. These structures can be described as made of a CdSe dot and a CdS rod, both in the wurtzite phase with a high crystallinity of both the core and the rod. This result supports the effectiveness of high temperature colloidal synthesis in promoting the formation of core@shell nanocrystals with very low defectivity. On the other hand, data on the CdSe@CdS with octapod morphology suggest the occurrence of a core composed of a CdSe cubic sphalerite phase with eight pods made of CdS wurtzite phase. Our findings are compared to current models proposed for the design of functional heterostructures with controlled nanoarchitecture.

Subject Areas: Chemistry


Instruments: B18-Core EXAFS