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Article

Hydrothermal Synthesis of Iridium-Substituted NaTaO3 Perovskites

1
Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
2
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; https://doi.org/10.3390/nano11061537
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. https://doi.org/10.3390/nano11061537

AMA Style

Burnett DL, Vincent CD, Clayton JA, Kashtiban RJ, Walton RI. Hydrothermal Synthesis of Iridium-Substituted NaTaO3 Perovskites. Nanomaterials. 2021; 11(6):1537. https://doi.org/10.3390/nano11061537

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. https://doi.org/10.3390/nano11061537

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