Electrochemical Characterization of Magnetite (Fe₃O₄) Nanoaggregates in Acidic and Alkaline Solutions

Abstract

The electrochemical behavior of magnetite (Fe3O4) aggregates with submicrometric size is investigated. Specifically, cyclic voltammetry tests were performed in both acidic (pH ∼ 4.5) and alkaline (pH ∼ 12.8) solutions, exploiting a conventional three-electrode cell. In the first case, the working electrode was made of a glassy carbon substrate loaded with magnetite nanoaggregates, forming a continuous film. In a second configuration, magnetite nanoaggregates were dispersed in solution, kept under stirring, as a fluidized electrode. The latter approach showed an increase in the electrochemical response of the particles, otherwise limited by the reduced active area as in the former case. Electrochemical-atomic force microscopy (EC-AFM) investigation was carried out in an acidic environment, showing the topography evolution of nanoaggregates during the electrochemical characterization. X-ray diffraction (XRD) analysis was carried out to evaluate the microstructural variation in the Fe3O4 electrodes after cathodic polarization tests in an alkaline environment.

Cooperative Redox Transitions Drive Electrocatalysis of the Oxygen Evolution Reaction on Cobalt–Iron Core–Shell Nanoparticles

“…It should be mentioned that the Co L 2,3 -edge spectra are not modified even for potentials as low as −0.5 V vs RHE, suggesting that Co (II) is not reduced at these potentials (Figure S11 A) while the O K-edge spectra evidenced some changes related to the transformation of the spinel structure into the wüstite structure (Figure S11 B). Furthermore, no signature corresponding to the reduction to metallic iron was observed in the NEXAFS spectra contrary to what has been reported in some previous publications). (Note that if the potential was scanned further negative, the CV became irreversible (not shown), which we tentatively attribute to the reduction of Fe 3 O 4 to metallic Fe.)…”

Preparation of preceramic ferrocene-modified microparticles for the development of uniform porous iron oxide particles and their sustainable recycling

“…For this purpose, measurements in an alkaline solution (1 M NaOH) were performed in an aqueous solution representing standard conditions where iron-based ceramics are used in electrochemical devices. 56 Despite multiple electrochemical investigations of the system of iron and iron oxides, the discussed mechanism is often different, but most authors agree with the described evaluation. 20,[57][58][59] The ceramics based on the PSOH@Fc particles synthesized in synthetic 11a).…”

“…For this purpose, measurements in an alkaline solution (1 M NaOH) were performed in an aqueous solution representing standard conditions where iron-based ceramics are used in electrochemical devices. 56…”

Immobilizing nanozymes on 3D-printed metal substrates for enhanced peroxidase-like activity and trace-level glucose detection

“…† The CV profile of MIL88B consists of a peak corresponding to the oxidation of Fe 2+ to Fe 3+ at 1.1 V and a peak related to the reduction of Fe 3+ to Fe 2+ at −0.3 V. 27,28 The reduction and oxidation peaks shifted in the degraded MOF (DEG 500) as compared to MIL88B, which is most likely correlated with the presence of both Fe 2 O 3 and Fe 3 O 4 phases. 29,30 BET surface area and FT-IR spectroscopic study…”