Electrografting of 3-Aminopropyltriethoxysilane on a Glassy Carbon Electrode for the Improved Adhesion of Vertically Oriented Mesoporous Silica Thin Films

Abstract

Vertically oriented mesoporous silica has proven to be of interest for applications in a variety of fields (e.g., electroanalysis, energy, and nanotechnology). Although glassy carbon is widely used as an electrode material, the adherence of silica deposits is rather poor, causing mechanical instability. A solution to improve the adhesion of mesoporous silica films onto glassy carbon electrodes without compromising the vertical orientation and the order of the mesopores will greatly contribute to the use of this kind of modified carbon electrode. We propose here the electrografting of 3-aminopropyltriethoxysilane on glassy carbon as a molecular glue to improve the mechanical stability of the silica film on the electrode surface without disturbing the vertical orientation and the order of the mesoporous silica obtained by electrochemically assisted self-assembly. These findings are supported by a series of surface chemistry techniques such as X-ray photoelectron spectroscopy, scanning and transmission electron microscopy, and cyclic voltammetry. Finally, methylviologen was used as a model redox probe to investigate the cathodic potential region of both glassy carbon and indium tin oxide electrodes modified with mesoporous silica in order to demonstrate further the interest in the approach developed here.

Enhanced PEDOT adhesion on solid substrates with electrografted P(EDOT-NH 2 )

“…Compared to the relatively slow SAM and silanization methods, surface modification through electrografting only takes several minutes. Furthermore, a variety of materials have been used as the conducting substrate, including gold, platinum, glassy carbon, stainless steel, nickel, silicon, and ITO ( 46 , 47 , 50 ). …”

Electrochemically Assisted Deposition of Nanoporous Silica Membranes on Gold Electrodes: Effect of 3‐Mercaptopropyl(trimethoxysilane) “Molecular Glue” on Film Formation, Permeability and Metal Underpotential Deposition

“…Mesoporous silica films generated by EASA exhibit good adhesion to oxide‐based electrodes (such as ITO or FTO) thanks to the reaction of their surface hydroxyl groups with silica, [40,44] but may require an electrode surface pretreatment step in other cases [41,45,46] . Dealing with gold electrode, the direct deposition of mesoporous silica by EASA led to non‐uniformly deposited film which may even peel off from the electrode surface (Figure S1A).…”

“…In doing so, one can get vertically ordered silica mesochannel films with small pore diameter (2–3 nm), high packing density (>10 12 pores per cm 2 ) and mesochannel lengths typically in the 50–100 nm range [37,40] . These films are mechanically stable and well‐adherent when grown onto oxide‐based electrode surfaces likely to form covalent bonds with silica, but they may require the use of an additional adhesive layer to ensure strong attachment to other electrode materials (such as carbon, for instance) [41] . They exhibit molecular sieving properties at the nanoscale, demonstrating the very good quality of uniformly‐packed nanopores over wide area crack‐free films [42] .…”

Critical Effect of Film Thickness on Preconcentration Electroanalysis with Oriented Mesoporous Silica Modified Electrodes

“…The mesoporous silica films were prepared by electrochemically assisted self-assembly on APTES-electrografted glassy carbon electrodes (GCE), by adapting a previously described method [16]. Glassy carbon plates (SIGRA-DUR G, 20 mm 3 10 mm 3 1 mm) were purchased from HTW Germany.…”

“…Such films can be prepared by electro-assisted self-assembly (EASA) [11a, 14] or by the Stö ber solution growth process [11b], which are the two most versatile methods available to date to prepare vertically oriented mesoporous silica films on electrodes giving rise to well-defined electrochemical characteristics [15]. Good adhesion to the support is ensured for films generated as such onto electrode surfaces bearing surface hydroxyl groups, whereas using "molecular glue" is mandatory for other electrode substrates (such as electrografting of 3-aminopropyltriethoxysilane on glassy carbon [16]) prior to film deposition. Electroanalytical interests have been reported for surfactant-containing, template-extracted, organically functionalized, and free-standing oriented mesoporous silica thin films [12].…”