Rhodium(III) oxide
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3D model (
JSmol ) |
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ECHA InfoCard
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100.031.666 |
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PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| Rh2O3 | |
| Molar mass | 253.8092 g/mol |
| Appearance | dark grey odorless powder |
| Density | 8.20 g/cm3 |
| Melting point | 1,100 °C (2,010 °F; 1,370 K) (decomposes) |
| insoluble | |
| Solubility | insoluble in aqua regia |
| +104.0·10−6 cm3/mol | |
| Structure[1] | |
hexagonal (corundum )
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| R3c | |
a = 512.7 pm (hexagonal setting), c = 1385.3 pm (hexagonal setting)
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| Hazards | |
| GHS labelling:[2] | |
 
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| Danger | |
| H302+H332, H315, H319, H335 | |
| P280, P301+P330+P331, P302+P352, P304+P340, P312, P332+P313, P337+P313 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Rhodium(III) oxide (or Rhodium sesquioxide) is the inorganic compound with the formula Rh2O3. It is a gray solid that is insoluble in ordinary solvents.
Structure
Rh2O3 has been found in two major forms. The hexagonal form adopts the
orthorhombic structure when heated above 750 °C.[1]
Production
Rhodium oxide can be produced via several routes:
- Treating RhCl3 with oxygen at high temperatures.[3]
- Rh metal powder is fused with potassium hydrogen sulfate. Adding sodium hydroxide results in hydrated rhodium oxide, which upon heating converts to Rh2O3.[4]
- Rhodium oxide thin films can be produced by exposing Rh layer to oxygen plasma.[5]
- Nanoparticles can be produced by the hydrothermal synthesis.[6]
Physical properties
Rhodium oxide films behave as a fast two-color electrochromic system: Reversible yellow ↔ dark green or yellow ↔ brown-purple color changes are obtained in KOH solutions by applying voltage ~1 V.[7]
Rhodium oxide films are transparent and conductive, like
organic light-emitting diodes.[5]
Catalytic properties
Rhodium oxides are
catalysts for hydroformylation of alkenes,[8] N2O production from NO,[9] and the hydrogenation of CO.[10]
See also
References
- ^ ISSN 0567-7408.
- ^ GHS: Alfa Aesar 011814 SDS (Feb 2021)
- ^ H. L. Grube (1963). "The Platinum Metals". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. NY: Academic Press. p. 1588.
- ISSN 0020-1669.
- ^ ISSN 0003-6951.
- ISSN 1463-9076.
- ISSN 0013-4651.
- .
- ISSN 0926-860X.
- ISSN 0021-9517.