New electrocatalytic materials based on mixed metal oxides: electrochemical quartz crystal microbalance characterization

Abstract

An electrochemical Quartz Crystal Microbalance (EQCM) was used to characterize a mixed metal oxide electrocatalyst, Ir 0.15 Sn 0.85 O 2 , for the Oxygen Evolution Reaction (OER) in acidic medium in the potential range of the pseudo-capacitance reaction, from 0.4 to 1.2 V versus Reversible Hydrogen Electrode (RHE). The EQCM gold tip was characterized in H 2 SO 4 0.05 M and HClO 4 0.1 M. Subsequently, Ir 0.15 Sn 0.85 O 2 powder, synthesized by a solgel route, was supported on the tip gold surface for investigations in the same media. The simultaneous measurements of mass variation and current density as functions of potential led to the identification of the chemical species involved in the mass transfer between the oxide and the acidic solution during the pseudo-capacitance reaction.

Designing materials by means of the cavity-microelectrode: the introduction of the quantitative rapid screening toward a highly efficient catalyst for water oxidation

“…which is at the basis of the electrochemical properties of many conductive oxide materials. 28 Moreover, in a recent paper 19 we quantitatively demonstrated that the number of sites that participate in reaction (1) is proportional to the number of sites on which OER occurs:…”

Dynamic potential–pH diagrams application to electrocatalysts for wateroxidation

“…28,30 This phenomenon was recently verified by EQCM experiments. 31 In electrodeposited films, reaction (12) can involve almost every metal atom, since the entire film is fully hydrated (where the film is nanocrystalline or amorphous and the whole mass of the film has a very high surface to volume ratio). For thermally prepared oxides the pseudocapacitive process occurs only at the surface of crystallites, at least for freshly-prepared films, especially those treated by high-temperature dehydration and calcination.…”

IrO2-Based Disperse-Phase Electrocatalysts: A Complementary Study by Means of the Cavity-Microelectrode and Ex-Situ X-ray Absorption Spectroscopy

“…All SnO 2 –IrO 2 materials have been screened in a potential window in which iridium oxide shows pseudocapacitive – solid state redox transitions that can be described by the following equation: MO italicx false( OH false) italicy + normalδ normalH + false( solution false) + normalδ normale − false( oxide false) → MO italicx − normalδ false( OH false) italicy + normalδ (where M is the metal ion center, in this case Ir) which is at the basis of the electrochemical properties of many conductive oxide materials. Recently, we proved the validity of eq in the case of SnO 2 –IrO 2 composites by using the electrochemical quartz crystal microbalance (EQCM) . In particular, the capacitive, analytical (as pH sensor), electrochromic, and electrocatalytic properties of IrO 2 , strictly depend on the rapid solid state redox transition that occurs together with the exchange of protons with the solution.…”

“…Recently, we proved the validity of eq 1 in the case of SnO 2 −IrO 2 composites by using the electrochemical quartz crystal microbalance (EQCM). 15 In particular, the capacitive, analytical (as pH sensor), electrochromic, and electrocatalytic properties of IrO 2 14,16 strictly depend on the rapid solid state redox transition that occurs together with the exchange of protons with the solution.…”