Electrochemical Behaviour of PSS-Functionalized Silica Films Prepared by Electroassisted Deposition of Sol–Gel Precursors

Porous, electrically insulating SiO2 layers containing polystyrene sulfonate (PSS) were deposited on glassy carbon electrodes by an electrochemically assisted deposition method. The obtained material was characterized by microscopic, spectroscopic and thermal techniques. Silica-PSS films modify the electrochemical response of the glassy carbon electrodes against selected redox probes. Positively charged species show reduced diffusivities across the SiO2-PSS pores, which resulted in a concentration ratio higher than 1 for these species. The opposite behaviour was found for negatively charged redox probes. These observations can be interpreted in terms of the different affinity of the GC/SiO2-PSS-modified electrode for the electroactive species, as a consequence of the negatively charged porous silica.

Financial support from the Spanish Ministerio de Economía y Competitividad and FEDER (MAT2010-15273) and Fundación Ramón Areces is gratefully acknowledged. Financial support from the Generalitat Valenciana is acknowledged (PROMETEO2013/038). A.G.Q. thanks go to Generalitat Valenciana for a Santiago Grisolia grant. D.S.T. thanks Spanish Ministerio de Economía y Competitividad for an FPI grant (BES-2010-035238).