Synthesis of Thiol Functionalized Multi-walled Carbon Nanotube/Gold Nanoparticle Composites

Abstract

Multi-wall carbon nanotubes (MWNTs) were functionalized with 4-mercaptobenzoic acid (4-MBAc) in a polyphosphoric acid (PPA)/phosphorous pentoxide (P2O5). The resultant 4-mercaptobenzoyl-functionalized MWNT (MB-MWNT) was used to immobilize gold nanoparticles (GNPs) via the covalent Au-S bonds. The process involved that GNPs were in-situ synthesized in the presence of MB-MWNT and stabilized by trisodium citrate and sodium borohydride (NaBH4) to covalently deposit onto the surface of MB-MWNTs. The morphology of resultant MB-MWNT/GNP composite showed that GNPs are uniformly distributed on the surface of MB-MWNTs. HR-TEM and XPS studies revealed that GNPs showed well-defined crystal structure. Cyclic voltammetries of MB-MWNT and MB-MWNT/GNP composite showed that MB-MWNT/GNP composite displayed profoundly improved electrocatalytic activity over MB-MWNT.