Morphology control of 1D noble metal nano/heterostructures towards multi-functionality

We synthesize Pt, Pd, Au and layered multimaterial nanotubes via electrodeposition in anodic aluminium oxide (AAO) templates. We show that time controlled growth at constant electrolyte concentration allows the morphology and chemistry of the nanostructure to be controlled to a high degree. In particular the wall thickness of the nanotubes can be tuned from thin wall nanotubes to nanorods. The applications targeted are electrocatalysis, plasmon resonance and molecular detection via surface enhanced Raman spectroscopy (SERS). The electro-oxidation of methanol on Pt and that of formic acid on Pd are investigated and compared with state of the art Pt/C and Pd/C catalysts and some of the recent similar work from the literature. Nanotubes of both metals (Pt, Pd) show very high electrochemical surface area (ECSA) and enhanced electrocatalytic activity. Our electrocatalysis results show great promise towards direct liquid fuel cells. In terms of molecular detection using SERS we show that the SERS activity of Au-nanostructures is strongly dependent on morphology with very high SERS enhancements being related to partly filled Au-nanotubes. Noble metal nanostructures of different morphologies and heterostructures are obtained in AAO templates via a simple control of deposition time. Electrocatalysis, plasmon resonance and SERS activity show a strong dependence on morphology.