A versatile and modular approach to modify silicon surfaces for electrochemical applications

摘要

The thesis presents the research results obtained while studying novel chemical strategies for preparing Si(100)-based electrochemical platforms suitable for aqueous environments. A primary research aim was the preparation of well-passivated Si(100) surfaces amenable to further chemical derivatization.The preparation and functionalization of alkyne-terminated alkyl monolayers on Si(100) surfaces using the Huisgen 1,3-dipolar ‘click’ cycloaddition of azides with surface-bound acetylenes is reported and shown to be a versatile, experimentally simple, chemically unambiguous modular approach to modified silicon surfaces. Covalently immobilized, structurally well-defined acetylenyl organic monolayers are prepared from a commercially available α,ω-diyne (1,8-nonadiyne) species using a one-step thermal hydrosilylation procedure. Subsequent derivatization of the alkyne-terminated monolayers in aqueous environments with representative azide species affords disubstituted surface-bound [1,2,3]-triazole species. Neither activation procedures nor protection/deprotection schemes are required, as is the case with more established grafting approaches for silicon surfaces. The described surface modification scheme has been used in preparing modified Si(100) electrode surfaces, where modular components such as ferrocene derivatives or electrochemically ‘switchable’ linker molecules are introduced onto the passivated silicon surface. An implementation study to prepare modified light-addressable ‘switchable’ Si(100) electrodes is also reported.Negligible oxidation of the substrate was generally observed after exposure to aqueous systems for extended periods (tens of hours), and the electroactive monolayers showed a robust and reversible behaviour. The proposed concept of modular components and high-yielding coupling procedures has been shown on Si(100) surfaces and also extended to illustrate the functionalization of porous silicon rugate filters.