Manipulation of Phase and Microstructure at Nanoscale for SiC in Molten Salt Synthesis

Silicon carbide (SiC) is a compound with strong covalent bonding, which gives its high mechanical strength and oxidation resistance, but also hinders its synthesis under moderate conditions. Herein, a facile route is presented for the synthesis of SiC nanomaterials from simple and abundant raw materials in an inorganic molten salt (MS). With this route, we are able to synthesis nanoscale 3C-SiC and 2H-SiC in a controlled manner, where the choice of cubic or hexagonal structure is coupled to nanocrystal size. By selection of the starting materials and tuning of the synthesis conditions, the MS-derived SiC can be isolated as nanoparticles (NPs), porous SiC/C composites with small primary crystals (2–4 nm), and as nanospheres. We also show that the SiC nanostructures are active for electrochemical hydrogen evolution reaction, and the activity can be remarkably improved by loading Pt (NPs) onto the structure.