SiC whiskers nucleated on rGO and its potential role in thermal conductivity and electronic insulation

Abstract SiC whisker (SiCw) anchoring on reduced graphene oxide (rGO) is a promising thermal conductive filler, which not only constructs the high-effective phonon transmission pathway but also resolves the agglomeration phenomenon of rGO. However, how to quantificationally anchor SiCw on rGO to build a phonon transmission pathway is incompletely understood. That is, the nucleation mechanism of SiCw requires a full investigation. Here, SiCw@rGO was synthesized by stacking bed method using rGO and rice husk ash as materials, in which SiCw is bridged on the rGO sheets through SiC crystal nucleus (C-Si covalent bonds). The experimental and density functional theoretical results reveal that the oxygen-containing defects (C-O groups) of rGO provide favorable sites for SiC nucleation and promote the yield of SiCw. Additionally, some specific defects of rGO induce the unpaired electrons of the surrounding carbon atoms, which is the prerequisite of the formation of C-Si covalent bonds. The construction of C-Si bonds between SiCw and rGO serves to enhance phonon accessibility, making SiCw@rGO composites achieve good thermal conductivity property and electrical insulation performance. The combination of experimental and theoretical research provides guides for the design of high-efficient thermal conductive materials.