Cu2S Nanodisks

Fig. 20.1 (a) TEM image of CU2S ribbons of stacked nanodisks. Schematic of nanodisks oriented (b) perpend to the substrate into a rodlike array, and (c) tilted to the substrate, demonstrating the overlap of each disk when imaged with TEM [4]. 

A method closely related to thermolysis has been used by Korgel and coworkers [506 508] to synthesize nanocrystals in different shapes. In this method, long-chain alkanethiolates of metals such as Cu and Ni are mixed with fatty acids to obtain a waxy solid which is thermally decomposed. Thus, nanorods, nanodisks, or nanoprisms of CU2S [506, 507] and NiS [508] have been prepared by this method (see Fig. 2.25). 

Fig. 5 TEM images of Cu2 xS nanoparticles (a) spheres, (b) circular nanodisks and (c) hexagonal nanodisks. Scale bars = 200 run. Reproduced with permission from reference 40. Copyright The Royal Society of Chemistry 2011. 

Cu2-xSe NCs have also been prepared from a new selenium precursor l,3-dimethylimidazoline-2-selenone. In a typical reaction, the selenium precursor was rapidly injected in to a hot CuCl2-OAm solution heated at 175 °C to produce cubic Cu2 xSe nanodisks of 17 1 nm diameter (Fig. 6(a)). The band gap of the NCs was found to be 1.55 eV and a film prepared from the NCs showed an increase in photocurrent under illumination. 

Fig. 6 TEM image of (a) Cu2.xSe nanodisks [Reproduced with permission from reference 44], (b) Cu2-xSe nanoerystals (Inset HRTEM of the individual nanocrystal). Reproduced with permission from referenee 46. Copyright American Chemical Society 2010 and 2011.

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