Chemical Stability of Mesoporous Oxide Thin Film Electrodes under Electrochemical Cycling: from Dissolution to Stabilization

Abstract

Mesoporous oxide thin films (MOTF) present very high surface areas and highly controlled monodisperse pores in the nanometer range. These features spurred their possible applications in separation membranes and permselective electrodes. However, their performance in real applications is limited by their reactivity. Here, we perform a basic study of the stability of MOTF toward dissolution in aqueous media using a variety of characterization techniques. In particular, we focus in their stability behavior under the influence of ionic strength, adsorption of electrochemical probes, and applied electrode potential. Mesoporous silica thin films present a limited chemical stability after electrochemical cycling, particularly under high ionic strength, due to their high specific surface area and the interactions between the electrochemical probes and the surface. In contrast, TiO 2 or Si 0.9 Zr 0.1 O 2 matrices present higher stability; thus, they are an adequate alternative to produce accessible, sensitive, and robust permselective electrodes or membranes that perform under a wide variety of conditions.

Influence of Nanoconfinement on the pKa of Polyelectrolyte Functionalized Silica Mesopores

“…Measurements were conducted with solution pH values ranging from 2 to 11 (Figure 2b) and using [Ru(NH 3 ) 6 ] 2+/3+ as probe molecule to investigate the gating behavior toward cations. Measuring time was adjusted to below 10 min to guarantee stability 22. The obtained peak current density ( j p ) values were plotted against the adjusted solution pH value and subjected to an empirical Boltzmann‐fit (for details see Tables S3–S5, Supporting Information).…”

Bimetallic Ag‐Au Nanoparticles Inside Mesoporous Titania Thin Films: Synthesis by Photoreduction and Galvanic Replacement, and Catalytic Activity

“…the pores were filled with the template) and, as a consequence, the application of the composites is very limited due to instability issues. TiO 2 as support represents a clear advantage in terms of chemical and mechanical stability and can also provide new features to the composite, due to the well‐known synergy between metals and semiconductors . In fact, a recent article presented the promising photocatalytic activity of composites prepared by plasma deposition of Au–Ag bimetallic particles on top of a TiO 2 porous film prepared by magnetron sputtering …”

Gold semicontinuous thin-film-coated mesoporous TiO2 for SERS substrates

“…These results indicate a better adhesion of the Au film over TiO 2 in comparison with SiO 2 films. Interestingly, no adhesion layer was needed to maintain Au attached to the TiO 2 film, a feature that can be attributed to metal/oxide interactions and the oxide chemical stability [62,63]. Figure 3a, b show SEM images of TNM/Au8nm and TF/ Au8nm samples after incubation with the SERS probe.…”