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Emerging electrochemistry of high-concentration colloids: Redox-activity, wide potential window and electrophoretic transport of iron oxide nanoparticles
- High-concentration, steric stabilizer free colloids and particularly their electrochemical behavior remains almost unexplored. Herein, we report on the electrochemistry (cyclic voltammetry, impedance spectroscopy, etc.) of highly concentrated aqueous colloidal dispersion up to 800 g/L of citrate-capped ∼11 nm Fe3-xO4 nanoparticles (NPs) without background electrolyte on glassy carbon electrodes. X-ray photoelectron spectroscopy was applied to analyze the reaction products. Solid-state Fe(II)/Fe(III) conversion was concluded to determine the cathodic and anodic faradaic reactions of the particles, with the currents depending on approximately square root of the concentration. The electrochemical reactions are coupled with the electrophoretic transfer of the negatively charged NPs on toward the anode, with the ohmic-type behavior in the bulk demonstrated by the nearly linear voltametric cathodic curves and frequency-independent impedance above ∼10–100 Hz. Accumulation and clogging of theHigh-concentration, steric stabilizer free colloids and particularly their electrochemical behavior remains almost unexplored. Herein, we report on the electrochemistry (cyclic voltammetry, impedance spectroscopy, etc.) of highly concentrated aqueous colloidal dispersion up to 800 g/L of citrate-capped ∼11 nm Fe3-xO4 nanoparticles (NPs) without background electrolyte on glassy carbon electrodes. X-ray photoelectron spectroscopy was applied to analyze the reaction products. Solid-state Fe(II)/Fe(III) conversion was concluded to determine the cathodic and anodic faradaic reactions of the particles, with the currents depending on approximately square root of the concentration. The electrochemical reactions are coupled with the electrophoretic transfer of the negatively charged NPs on toward the anode, with the ohmic-type behavior in the bulk demonstrated by the nearly linear voltametric cathodic curves and frequency-independent impedance above ∼10–100 Hz. Accumulation and clogging of the NPs retards diffusion near anode. Hydrogen and especially oxygen evolution are arrested, and very large oxidation overpotentials result in extraordinary wide, up to 12 V, electrochemical window of water stability. The findings shed light onto basic features of the electrochemistry of high-concentration colloids without added electrolyte and their potential applications in redox flow batteries, electrophoretic deposition and beyond.…


| Autor*innen: | Yuri Mikhlin, Anya Muzikansky, Melina Zysler, Andreas ThünemannORCiD, David Zitoun |
|---|---|
| Dokumenttyp: | Zeitschriftenartikel |
| Veröffentlichungsform: | Verlagsliteratur |
| Sprache: | Englisch |
| Titel des übergeordneten Werkes (Englisch): | Journal of Colloid and Interface Science |
| Jahr der Erstveröffentlichung: | 2026 |
| Organisationseinheit der BAM: | 6 Materialchemie |
| 6 Materialchemie / 6.5 Synthese und Streuverfahren nanostrukturierter Materialien | |
| Veröffentlichende Institution: | Bundesanstalt für Materialforschung und -prüfung (BAM) |
| Verlag: | Elsevier Inc. |
| Jahrgang/Band: | 703 |
| Aufsatznummer: | 139247 |
| Erste Seite: | 1 |
| Letzte Seite: | 18 |
| DDC-Klassifikation: | Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten |
| Freie Schlagwörter: | Nanoplastics; SAXS; Small-angle X-ray scattering |
| Themenfelder/Aktivitätsfelder der BAM: | Material |
| Material / Advanced Materials | |
| DOI: | 10.1016/j.jcis.2025.139247 |
| URN: | urn:nbn:de:kobv:b43-644340 |
| ISSN: | 0021-9797 |
| Verfügbarkeit des Dokuments: | Datei für die Öffentlichkeit verfügbar ("Open Access") |
| Lizenz (Deutsch): | Creative Commons - CC BY-NC - Namensnennung - Nicht kommerziell 4.0 International |
| Datum der Freischaltung: | 22.10.2025 |
| Referierte Publikation: | Ja |
| Datum der Eintragung als referierte Publikation: | 03.11.2025 |
| Schriftenreihen ohne Nummerierung: | Wissenschaftliche Artikel der BAM |


