This work was funded by The Leverhulme Trust. A.T.V.
acknowledges the Xunta de Galicia (Spain) for a postdoctoral
fellowship. We thank Prof. Xiaogang Peng and Grace L. Ong
(University of Arkansas) for providing helpful QD synthetic
information. We would like to thank Dr Wuzong Zhou and
Ross Blackley at EaStCHEM-St. Andrews for the HRTEM
studies.