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
corundum structure. It transforms into an
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]
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]
^
abCoey, 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.
doi:
10.1107/s0567740870005022.
ISSN0567-7408.
^H. L. Grube (1963). "The Platinum Metals". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. NY: Academic Press. p. 1588.
^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.
ISSN0020-1669.
^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.
ISSN1463-9076.
^Gottesfeld, S. (1980). "The Anodic Rhodium Oxide Film: A Two-Color Electrochromic System". Journal of the Electrochemical Society. 127 (2). The Electrochemical Society: 272.
doi:
10.1149/1.2129654.
ISSN0013-4651.
^Pino, P.; Botteghi, C. (1977). "Aldehydes from olefins: cyclohexanecarboxaldehyde". Organic Syntheses. 57: 11.
doi:
10.15227/orgsyn.057.0011.
^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.
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10.1016/s0926-860x(01)00992-9.
ISSN0926-860X.