Electrochemical Methoxylation of Porous Silicon Surface

Abstract

An electrochemical process aiming at the grafting of methoxy groups on the hydrogenated porous silicon surface at room temperature has been designed. This takes place through partial anodic dissolution of porous silicon in anhydrous methanol. A dissolution mechanism is proposed by analogy with that of the anodic dissolution of ~ilicon in aqueous fluoride media. The methoxylated surface exhibits improved optical characteristics (increased photolun~nescence efficiency, blue shift of the emission), similar to porous silicon anodically oxidized in a nonfluoride aqueous electrolyte. Its stability against aging is also improved as compared to that of the hydrogenated surface, but without reaching the stability of anodically oxidized porous silicon. This residual sensitivity to aging is ascribed to the nonnegligible amount of Sill species which remains on the methoxylated surface upon the modification process.

An AFM, XPS and electrochemical study of molecular electroactive monolayers formed by wet chemistry functionalization of H-terminated Si(100) with vinylferrocene

“…In the case of VFC, which is a solid with a low melting T (323 K), hydrosilylation can be obtained by formation of Si radicals through Si-H homolysis, activated via UV-or visible-light exposure, or by heating. Alternative, more elaborate methods have been proposed for alkenes, as halogenation of the surface [8], thermal reaction of Grignard compounds [15], activation of the surface by radicals [6], electrochemistry [11,32]. In the present study, an effort has been made to explore a simple, reproducible and mild anchoring route, which implies, i.a., to expose the H-terminated Si(1 0 0) surface only to one chemical during the delicate phase of anchoring.…”

Electrochemically Assisted Covalent Modification of Carbon Electrodes

“…The proposed attachment mechanism is the same as that for HGC surfaces proceeding via formation of an aryl radical which abstracts H from the surface producing a Si radical which couples with a second aryl radical giving a Si±C bond. Less well-characterized is the procedure of electrochemically oxidizing H-terminated porous Si in the presence of anhydrous methanol [51]. A methoxylated Si surface results and the reaction is presumed to involve initial formation of a Si radical.…”

Wet chemical routes to the assembly of organic monolayers on silicon surfaces via the formation of Si–C bonds: surface preparation, passivation and functionalization

“…They showed that under anodic polarization, methoxy-terminated surfaces (RSi-OCH 3 and QSi-(OCH 3 ) 2 can be prepared. 192 The aryl diazonium approach benefits from the low cathodic overpotentials necessary to generate aryl radicals X-Ar-N 2 + + e À -X-Ar + N 2 (X = NO 2 , Br, COOH, CN)…”