Electrodeposited Silicate Films:  Importance of Supporting Electrolyte

Abstract

Silica and hybrid organic-inorganic films, ca. 100-200 nm thick, can be grown on glassy carbon electrodes through reactions initiated by electrogenerated hydroxide or hydronium ions in water under reductive and oxidative conditions, respectively. A variety of different alkoxysilanes (tetramethoxysilane and organoalkoxysilanes) and supporting electrolytes were used to evaluate whether film formation takes place on glassy carbon electrodes. The results of the study indicate that the acid-base properties of the supporting electrolyte are an important factor in determining whether film formation will take place. For cathodic electrodeposition, thin films can be formed using supporting electrolytes that are close to neutral, such as KCl, KNO3, and NaClO4. For anodic electrodeposition, thin films can be formed using supporting electrolytes that are acidic, such as, KH2PO4, HNO3, H2SO4, etc. The acidity/basicity effects of the electrolytes arise in part from the strong dependence of the hydrolysis and condensation rates of the silicon alkoxide precursors on pH.

Enhancement of the Electrochemical Performance of SWCNT dispersed in a Silica Sol-gel Matrix by Reactive Insertion of a Conducting Polymer

“…An alternative method, which has been the focus of several studies, is the electrochemical or electro-assisted deposition method [5][6][7][8][9]. In particular, Shacham et al.…”

Highly sensitive detection of hexavalent chromium utilizing a sol-gel/carbon nanotube modified electrode

“…A uniform, brown-hued iridescence is the most preferred in the films in this research. Brown films have shown to be the thinnest (between 75 and 100 nm), followed by light blue, as determined by Deepa and Collinson through the use of a surface profilometer [44, 54]. The thickest films that still show iridescence give yellow and red colorations [44, 54].…”

“…Note the extreme variation in color and thus uniformity in A as opposed to B. Also worth noting is the transition from generally thicker blue and yellow films (A and B) to a very thin brown film (C) [54]. The areas of B and C that bare cortex patterns were located directly over the center of the stir bar during film deposition, causing less sol movement and thicker films in that area.…”

“…The localized increase in pH catalyzes the hydrolysis of the sol, which immediately begins to condense onto the electrode. Because the gelation and the drying do not occur at the same time, as they do in physical depositions, the porosity is much larger [54]. Electrodeposition has proven to produce sol-gel films with more consistent film thicknesses than through past deposition techniques such as spin coating and dip coating [55].…”

Molecularly imprinted silica films prepared by electroassisted deposition for the selective detection of dopamine

“…The method for electroassisted deposition of silica has been Page 5 of 32 A c c e p t e d M a n u s c r i p t 5 extensively studied for the preparation of modified electrodes for several applications, including nanolithography, enzyme immobilization, ion-exchangers and electroanalysis, among others. [38][39][40][41][42] The application of negative current for the reduction of the solvent containing a silica precursor in the presence of a molecular template produces a silica film with encapsulated template molecule. The removal of the template (also performed by electrochemical method in the present work) produced a molecularly imprinted silica film, with improved selectivity towards the selected analyte.…”