DEPENDENCE OF DIPOLE LAYER ON GRAPHITE SURFACE ON SIZE OF CONTACTING GOLD NANOPARTICLES

Abstract

The interfacial dipole on pyrolytic graphite surface shows a high dependence with size and coverage of gold nanoparticles. Small nanoparticles with an average size of 2.4 nm exhibit a large dipole moment, decreasing with increasing particle diameter. The value becomes negative for nanoparticles > 6 nm. The behaviour is described by charge densities created after charge transfer between individual gold nanoparticles and graphite surface. The subsequent decrease in dipole for large nanoparticles is shown to be due to depolarization effects. The study provides a novel method to control electronic properties at metal-graphite interface which is useful in graphene electronic devices and catalysis on support.