Figure 2 A) Schemes of surface diffusion (middle) or inward diffusion (right) of the metal phase after surface nucleation. B) Scanning transmission electron microscopy (STEM) image of the CdSe-Au heterostructure after 1 h of reaction. C) TEM image of CdSe-Au heterostructure after 4 h of reaction. The scale bar is 20 nm. A) Reproduced with permission.[5e] Copyright 2010, Wiley-VCH. B-C) Reproduced with permission.[7] Copyright 2013, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.
2.3. Solution-liquid-solid method
SLS method is a facile synthetic approach for hybrid nanorods using the pre-synthesized metal nanoparticles. In this process, metal nanoparticles with low melting points introduced in the organic solvent are transformed into liquid metal clusters as a catalyst on which nanocrystals are precipitated, and the growth of crystals on metal droplets occurs only at the interface between them.[1f,8] Being different from the methods of surface nucleation and materials diffusion which require careful control of synthesis conditions, the ease and robustness of this method open new opportunities for the preparation of high quality 1D hybrid nanostructures with relevance in photocatalytic applications.[1f, 8d] Shen et al. prepared Ag-ZnS nanorods by the SLS method (Figure 3B, 3C) by optimizing the diameter of Ag nanocrystals, the concentration of Zn precursor, reaction time, reaction temperature and other conditions to effectively control the diameter and length of Ag-ZnS nanorods hybrid nanostructures.[9]