Effect of surface modification on the stability and thermal conductivity of water-based SiO2-coated graphene nanofluid

•SiO2-coating modification can be applied in graphene nanofluid preparation.•SiO2-coating can improve stability and thermal conductivity of graphene nanofluid.•Graphene/SiO2 nanofluid has better performance than graphene-SDBS nanofluid.

SiO2-coated graphene was prepared by chemical liquid deposition method by using tetraethyl orthosilicate (TEOS), and then SiO2 particles were successfully coated on the graphene surface. A new kind of stable water-based graphene nanofluid was further prepared using the functionalized nanomaterial (graphene/SiO2). The effect of SiO2-coated modification on the stability and thermal conductivity of water-based graphene nanofluid was examined. The results showed that SiO2-coated modification significantly improved the hydrophilicity of graphene, as well as the stability and thermal conductivity of water-based graphene nanofluid. SiO2-coating can improve thermal conductivity better than surfactants for preparing water-based graphene nanofluid.