Formation of Bi2Ir nanoparticles in a microwave-assisted polyol process revealing the suboxide Bi4Ir2O. Issue 47 (22nd November 2021)

• Record Type: Journal Article
• Authors: Smuda, Matthias; Finzel, Kati; Hantusch, Martin; Ströh, Jonas; Pienack, Nicole; Khadiev, Azat; Terraschke, Huayna; Ruck, Michael; Doert, Thomas
• Is Part Of: Dalton transactions. Volume 50:Issue 47(2021)
• Page Start: 17665
• Page End: 17674
• Publication Date: 2021-11-22
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d1dt03199f
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : The new suboxide Bi4 Ir2 O was found as an intermediate in the formation of the intermetallic phase Bi2 Ir by a microwave-assisted polyol process. Abstract : Intermetallic phases are usually obtained by crystallization from the melt. However, phases containing elements with widely different melting and boiling points, as well as nanoparticles, which provide a high specific surface area, are hardly accessible via such a high-temperature process. The polyol process is one option to circumvent these obstacles by using a solution-based approach at moderate temperatures. In this study, the formation of Bi2 Ir nanoparticles in a microwave-assisted polyol process was investigated. Solutions were analyzed using UV–Vis spectroscopy and the reaction was tracked with synchrotron-based in situ powder X-ray diffraction (PXRD). The products were characterized by PXRD and high-resolution transmission electron microscopy. Starting from Bi(NO3 )3 and Ir(OAc)3, the new suboxide Bi4 Ir2 O forms as an intermediate phase at about 160 °C. Its structure was determined by a combination of PXRD and quantum-chemical calculations. Bi4 Ir2 O decomposes in vacuum at about 250 °C and is reduced to Bi2 Ir by hydrogen at 150 °C. At about 240 °C, the polyol process leads to the immediate reduction of the two metal-containing precursors and crystallization of Bi2 Ir nanoparticles.