Growth and Patterning of Pt Nanowires on Silicon Substrates

This paper describes a simple procedure for growing dense films of Pt nanowires directly on silicon substrates by modifying the surface through chemical or physical means. In the former, a self-assembled monolayer of (3-mercaptopropyl)-trimethoxysilane (MPTMS) is applied which can strongly bind Pt(0) nuclei to the surface through Pt–S linkages. Once attached, the Pt(0) nuclei can act as catalytic sites for the growth of Pt nanowires along the 〈111 〉direction. Alternately, relief features are physically created on the surface in order to generate nucleation and binding sites for Pt(0) nuclei, due to the higher free energy associated with a rough surface. Additionally, Pt nanowires have been successfully produced in well-defined patterns by scouring grooves on the silicon surface or by photochemically patterning the MPTMS monolayers with a shadow mask. We have also measured the electrochemical properties of these immobilized or patterned Pt nanowires. The results provide an effective route to producing dense films of Pt nanowires with high surface areas for various electrochemical applications.