Rhodium(III) oxide

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Rhodium(III) oxide
Rhodium(III) oxide Haematite-unit-cell-3D-balls.png
Rhodium(III) oxide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.031.666 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 234-846-9
PubChem CID
UNII
  • InChI=1S/3O.2Rh/q3*-2;2*+3
  • [O-2].[O-2].[O-2].[Rh+3].[Rh+3]
Properties
Rh2O3
Molar mass 253.8092 g/mol
Appearancedark 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)
R3c
a = 512.7 pm (hexagonal setting), c = 1385.3 pm (hexagonal setting)
Hazards
GHS labelling: [2]
GHS-pictogram-rondflam.svg GHS-pictogram-exclam.svg
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 Rh2 O3. It is a gray solid that is insoluble in ordinary solvents.

Contents

Structure

Rh2O3 has been found in two major forms. The hexagonal form adopts the corundum structure. It transforms into an orthorhombic structure when heated above 750 °C. [1]

Production

Rhodium oxide can be produced via several routes:

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 indium tin oxide (ITO) - the common transparent electrode, but Rh2O3 has 0.2 eV lower work function than ITO. Consequently, deposition of rhodium oxide on ITO improves the carrier injection from ITO thereby improving the electrical properties of 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

  1. 1 2 Coey, J. M. D. (1970-11-01). "The crystal structure of Rh2O3". Acta Crystallographica Section B: Structural Crystallography and Crystal Chemistry. 26 (11). International Union of Crystallography (IUCr): 1876–1877. Bibcode:1970AcCrB..26.1876C. doi:10.1107/s0567740870005022. ISSN   0567-7408.
  2. ↑ GHS: Alfa Aesar 011814 SDS (Feb 2021)
  3. ↑ H. L. Grube (1963). "The Platinum Metals". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. NY: Academic Press. p. 1588.
  4. ↑ Wold, Aaron; Arnott, Ronald J.; Croft, William J. (1963). "The Reaction of Rare Earth Oxides with a High Temperature Form of Rhodium(III) Oxide". Inorganic Chemistry. 2 (5). American Chemical Society (ACS): 972–974. doi:10.1021/ic50009a023. ISSN   0020-1669.
  5. 1 2 Kim, Soo Young; Baik, Jeong Min; Yu, Hak Ki; Kim, Kwang Young; Tak, Yoon-Heung; Lee, Jong-Lam (2005-08-15). "Rhodium-oxide-coated indium tin oxide for enhancement of hole injection in organic light emitting diodes". Applied Physics Letters. 87 (7). AIP Publishing: 072105. Bibcode:2005ApPhL..87g2105K. doi:10.1063/1.2012534. ISSN   0003-6951.
  6. ↑ Mulukutla, Ravichandra S.; Asakura, Kiyotaka; Kogure, Toshihiro; Namba, Seitaro; Iwasawa, Yasuhiro (1999). "Synthesis and characterization of rhodium oxide nanoparticles in mesoporous MCM-41". Physical Chemistry Chemical Physics. 1 (8). Royal Society of Chemistry (RSC): 2027–2032. Bibcode:1999PCCP....1.2027M. doi:10.1039/a900588i. ISSN   1463-9076.
  7. ↑ Gottesfeld, S. (1980). "The Anodic Rhodium Oxide Film: A Two-Color Electrochromic System". Journal of the Electrochemical Society. 127 (2). The Electrochemical Society: 272. Bibcode:1980JElS..127..272G. doi:10.1149/1.2129654. ISSN   0013-4651.
  8. ↑ Pino, P.; Botteghi, C. (1977). "Aldehydes from olefins: cyclohexanecarboxaldehyde". Organic Syntheses. 57: 11. doi:10.15227/orgsyn.057.0011.
  9. ↑ Mulukutla, Ravichandra S; Shido, Takafumi; Asakura, Kiyotaka; Kogure, Toshihiro; Iwasawa, Yasuhiro (2002). "Characterization of rhodium oxide nanoparticles in MCM-41 and their catalytic performances for NO–CO reactions in excess O2". Applied Catalysis A: General. 228 (1–2). Elsevier BV: 305–314. Bibcode:2002AppCA.228..305M. doi:10.1016/s0926-860x(01)00992-9. ISSN   0926-860X.
  10. ↑ Watson, P; Somorjai, G. A. (1981). "The hydrogenation of carbon monoxide over rhodium oxide surfaces" . Journal of Catalysis. 72 (2). Elsevier BV: 347–363. doi:10.1016/0021-9517(81)90018-x. ISSN   0021-9517.
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