PVP-assisted synthesis of dense silica-coated graphite with electrically insulating property

Abstract In order to endow graphite with an electrical insulating property, graphite flakes were coated with dense amorphous silica by polyvinylpyrrolidone (PVP) as a coupling agent between graphite and silica. First, PVP was physically adsorbed on graphite in water. Later on, silica layers were grown on the PVP-adsorbed graphite by a basic sol–gel reaction of tetraethyl orthosilicate (TEOS) in ethanol, resulting in dense amorphous silica-coated graphite. This silica-coated graphite is categorized as an electrical insulator with a high surface resistivity (2.14×10 12 Ω/sq), originating from very high surface coverage of the silica on the graphite.