Exploration into the Syntheses of Gallium- and Indiumborates under Extreme Conditions: M5 B12 O25 (OH): Structure, Luminescence, and Surprising Photocatalytic Properties

Daniela Vitzthum; Klaus Wurst; Johann M Pann; Peter Brüggeller; Markus Seibald; Hubert Huppertz

doi:10.1002/anie.201804083

Exploration into the Syntheses of Gallium- and Indiumborates under Extreme Conditions: M₅ B₁₂ O₂₅ (OH): Structure, Luminescence, and Surprising Photocatalytic Properties

Angew Chem Int Ed Engl. 2018 Aug 27;57(35):11451-11455. doi: 10.1002/anie.201804083. Epub 2018 Jul 26.

Authors

Daniela Vitzthum¹, Klaus Wurst¹, Johann M Pann¹, Peter Brüggeller¹, Markus Seibald², Hubert Huppertz¹

Affiliations

¹ Institut für Allgemeine, Anorganische und Theoretische Chemie, Leopold-Franzens-Universität Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria.
² OSRAM Opto Semiconductors GmbH, Mittelstetter Weg 2, 86830, Schwabmünchen, Germany.

Abstract

Explorative solid-state chemistry led to the discovery of the two new compounds Ga₅ B₁₂ O₂₅ (OH) and In₅ B₁₂ O₂₅ (OH). Extreme synthetic conditions within the range of 12 GPa and a temperature of 1450 °C realized in a Walker-type multianvil apparatus resulted in the formation of an unprecedented tetragonal structure with the exclusive presence of condensed BO₄ tetrahedra, forming cuboctahedral cavities. Doping of these cavities with Eu³⁺ in In₅ B₁₂ O₂₅ (OH) yielded in an orange-red luminescence. Photocatalytic tests of In₅ B₁₂ O₂₅ (OH) revealed a hydrogen production rate comparable to TiO₂ but completely co-catalyst free.

Keywords: borates; high-pressure synthesis; luminescence; photocatalytic hydrogen production; structure elucidation.