The oleic acid (OA)/metallic precursors ratio was slightly increased from 2.6 (on large-scale) to 3 (on small scale). The temperature and heating rate at the nucleation and growth steps were maintained invariable in both syntheses. As common steps, the mixture was mechanically stirred (100 rpm) under a smooth N2 flow, heated to 200 °C for 2 hours (5 °C/min) and afterwards heated to 285 °C (3 °C/min) for another 2 hours. Finally, the mixture was cooled down to room temperature by removing the heat source. An ethanol excess was added to the mixture, the black material was precipitated and separated with a permanent magnet. The product was then resuspended in hexane, and precipitated with ethanol four times, resulting in a brownish-black hexane dispersion that was stored at 4 °C for future use.