Construction of Organic Monolayers with Electron Transfer Function on a Hydrogen Terminated Si(111) Surface via Silicon–Carbon Bond and Their Electrochemical Characteristics in Dark and Under Illumination

An organic monolayer with a functional group of electron mediation capability, viologen, was constructed on a hydrogenterminated Si(111) surface via Si–C bond by photochemical attachment of 4-vinylbenzyl chloride followed by a surface quarternization reaction with 1-methyl-4-(4-pyridyl)pyridinium iodide. Furthermore, Pt particles were deposited on the monolayer by ion exchange reaction with PtCl42- followed by reduction by hydrogen gas. The mediation of electron transfer by viologen moieties was proved and electrochemical hydrogen evolution reaction rates were enhanced after the Pt deposition.