Tribochemical Surface Modification of Silicon

Herein, we introduce a tribochemical approach for activating silicon surfaces through mechanical scratching, triggering remarkably fast spontaneous reactions with organic molecules terminated with thiol (─SH), alcohol (─OH), or alkyne. The reaction proceeds under ambient conditions in dilute solutions (10-50 mM) without the need for light, elevated temperature, or external voltages. The resulting modified surfaces were characterized using electrochemical methods and x-ray photoelectron spectroscopy, confirming successful attachment of the molecules. Remarkably, the reaction occurs within only 10 s of exposure to dilute solutions of the molecule, yielding substantial surface coverages of silicon-bound ferrocenemethanol, 11-(ferrocenyl)undecanethiol, and ferrocene-terminated alkyne species of more than 10¹⁴ molecules cm^{- 2}. We attribute this reactivity to mechanically induced cleavage of Si─Si bonds, which generates highly reactive Si surface radicals that promote bond formation with the molecules. The ability to drive rapid reactions of Si with ─SH- and ─OH-containing molecules is particularly significant given the prevalence of these functional groups in biomolecules, highlighting the potential of this strategy for sensing at biointerfaces and for molecular electronics.