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Enhancing Electrical Conductivity and Catalytic Activity Through Controlled Crystallization of V2O5-Nb2O5-P2O5 Glass
* 1 , 1 , 1 , 2 , 2 , 3 , 4 , 1
1  Division of Materials Chemistry, Ruđer Bošković Institute, Bijenička cesta 54, Zagreb, Croatia
2  Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Pardubice, Czech Republic
3  Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, Zagreb, Croatia
4  Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, Zagreb, Croatia
Academic Editor: Cosimo Trono

Published: 31 October 2023 by MDPI in 4th International Electronic Conference on Applied Sciences session Poster Session

Glassy and glass-ceramic materials based on V2O5-P2O5 have been identified as highly promising cathode materials for rechargeable Li-ion, Na-ion, and all-solid-state batteries. These materials offer a compelling combination of high safety, exceptional energy density, and extended cycling life, making them highly promising1. In addition, such materials are also recognized as effective catalysts in oxidation reactions2. Furthermore, it has been acknowledged that the microstructural properties, electrical conductivity, and electrochemical properties of V2O5-P2O5-based glasses can be significantly improved through thermally controlled crystallization3. In light of this, this study aims to synthesize a glass with a nominal composition of 70V2O5-20Nb2O5-10P2O5 and investigate the influence of controlled crystallization at different temperatures and durations on the electrical and catalytic properties. The parent glass is prepared via the melt-quenching technique, and its thermal behavior is examined through differential thermal analysis (DTA). The samples subjected to controlled crystallization are qualitatively and quantitatively analyzed using powder X-ray diffraction (PXRD), while (micro)structural properties are assessed using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and infrared attenuated total reflectance spectroscopy (IR-ATR). Electrical transport is investigated by solid-state impedance spectroscopy (SS-IS) across a wide frequency (0.01 Hz to 1 MHz) and temperature range (–90 °C to 240 °C). The catalytic activity of prepared samples is tested in oxidation reactions of stearic acid and is monitored using TG-IR system. The findings of this research demonstrate a remarkable enhancement in electrical conductivity through thermal treatment of the parent glass, with the sample heat-treated at 380 °C exhibiting the highest conductivity of 1.58 × 10–3 S/cm @30 °C. Furthermore, these materials exhibit promising catalytic properties, unveiling new avenues for their application.

This work is supported by the Croatian Science Foundation under the projects IP-2018-01-5425 and DOK-2021-02-9665.

1. Kindle, M., Cha, Y., McCloy, J. S. & Song, M. K. Alternatives to Cobalt: Vanadate Glass and Glass-Ceramic Structures as Cathode Materials for Rechargeable Lithium-Ion Batteries. ACS Sustain. Chem. Eng. 9, 629–638 (2021).
2. Ballarini, N. et al. VPO catalyst for n-butane oxidation to maleic anhydride: A goal achieved, or a still open challenge? Top. Catal. 2006 381 38, 147–156 (2006).
3. Pietrzak, T. K., Wasiucionek, M. & Garbarczyk, J. E. Towards Higher Electric Conductivity and Wider Phase Stability Range via Nanostructured Glass-Ceramics Processing. Nanomaterials 11, 1321 (2021).

Keywords: vanadate-phosphate glasses ; glass-ceramics ; controlled crystallization ; structural properties ; electrical properties ; catalytic activity ; impedance spectroscopy