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Hydrothermal Synthesis of Iridium-Substituted NaTaO3 Perovskites

Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
Department of Physics, University of Warwick, Coventry CV4 7AL, UK
Author to whom correspondence should be addressed.
Academic Editors: Gimyeong Seong, Juan Carlos Rendón-Angeles and Yoon-Bong Hahn
Nanomaterials 2021, 11(6), 1537;
Received: 30 April 2021 / Revised: 19 May 2021 / Accepted: 7 June 2021 / Published: 10 June 2021
(This article belongs to the Special Issue Hydrothermal Synthesis of Nanoparticles)
Iridium-containing NaTaO3 is produced using a one-step hydrothermal crystallisation from Ta2O5 and IrCl3 in an aqueous solution of 10 M NaOH in 40 vol% H2O2 heated at 240 °C. Although a nominal replacement of 50% of Ta by Ir was attempted, the amount of Ir included in the perovskite oxide was only up to 15 mol%. The materials are formed as crystalline powders comprising cube-shaped crystallites around 100 nm in edge length, as seen by scanning transmission electron microscopy. Energy dispersive X-ray mapping shows an even dispersion of Ir through the crystallites. Profile fitting of powder X-ray diffraction (XRD) shows expanded unit cell volumes (orthorhombic space group Pbnm) compared to the parent NaTaO3, while XANES spectroscopy at the Ir LIII-edge reveals that the highest Ir-content materials contain Ir4+. The inclusion of Ir4+ into the perovskite by replacement of Ta5+ implies the presence of charge-balancing defects and upon heat treatment the iridium is extruded from the perovskite at around 600 °C in air, with the presence of metallic iridium seen by in situ powder XRD. The highest Ir-content material was loaded with Pt and examined for photocatalytic evolution of H2 from aqueous methanol. Compared to the parent NaTaO3, the Ir-substituted material shows a more than ten-fold enhancement of hydrogen yield with a significant proportion ascribed to visible light absorption. View Full-Text
Keywords: perovskite; tantalate; crystallisation; nanocrystals; photocatalysis; water splitting perovskite; tantalate; crystallisation; nanocrystals; photocatalysis; water splitting
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MDPI and ACS Style

Burnett, D.L.; Vincent, C.D.; Clayton, J.A.; Kashtiban, R.J.; Walton, R.I. Hydrothermal Synthesis of Iridium-Substituted NaTaO3 Perovskites. Nanomaterials 2021, 11, 1537.

AMA Style

Burnett DL, Vincent CD, Clayton JA, Kashtiban RJ, Walton RI. Hydrothermal Synthesis of Iridium-Substituted NaTaO3 Perovskites. Nanomaterials. 2021; 11(6):1537.

Chicago/Turabian Style

Burnett, David L., Christopher D. Vincent, Jasmine A. Clayton, Reza J. Kashtiban, and Richard I. Walton 2021. "Hydrothermal Synthesis of Iridium-Substituted NaTaO3 Perovskites" Nanomaterials 11, no. 6: 1537.

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