Carbon-coated mesoporous silica as an electrode material

Abstract

The entire pore surface of FSM-16 type mesoporous silica was uniformly coated with a thin carbon layer by carbonizing pre-doped organic-alcohol molecules onto the pore surface. The thickness of the carbon layer was estimated to be extremely thin, i.e., it corresponds to only 1–2 graphene layers. Even after the carbon-coating, FSM-16 preserves its intrinsic ordered pore structure (hexagonal array of cylindrical pores) and still possesses high surface area of 530 m 2 g −1, but its pore nature was completely converted into a hydrophobic one, which was revealed from a very small amount of water–vapor adsorption. We characterized the electrochemical properties of the carbon-coated FSM-16 together with the carbon-coated SBA-15 synthesized by using the same coating method. Both of them exhibited electric double-layer capacitance in 1 M H 2SO 4 and 1 M NaCl, and the values of the capacitance per surface area are comparable to those of conventional activated carbons. We can thus conclude that the present carbon-coating changes the nature of mesoporous silicas from an insulator to an electrical conductor with their ordered pore structures unchanged, and the carbon-coated mesoporous silicas can be used as electrode materials with uniform pores.